wwwbasic.js

// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

'use strict';

// ESM:
(function() {
  var DYNAMIC_HEAP_SIZE = 1024 * 1024 * 16;
  var STACK_SIZE = 64 * 1024;
  var MAX_DIMENSIONS = 7;

  var SIMPLE_TYPE_INFO = {
    'byte': {array: 'Uint8Array', size: 1, shift: 0, view: 'b'},
    'short': {array: 'Int16Array', size: 2, shift: 1, view: 'i16'},
    'long': {array: 'Int32Array', size: 4, shift: 2, view: 'i'},
    'single': {array: 'Float32Array', size: 4, shift: 2, view: 's'},
    'double': {array: 'Float64Array', size: 8, shift: 3, view: 'd'},
    'string': {array: 'Array', size: 1, shift: 0, view: 'str'},
  };

  var IMPLICIT_TYPE_MAP = {
    '$': 'string', '%': 'short', '&': 'long', '!': 'single', '#': 'double',
  };

  function NextChar(ch) {
    return String.fromCharCode(ch.charCodeAt(0) + 1);
  }

  function DecodeTag(code) {
    code = code.replace(/&lt;/g, '<');
    code = code.replace(/&gt;/g, '>');
    code = code.replace(/&amp;/g, '&');
    return code;
  }

  function Basic(code, options) {
    options = options === undefined ? {} : options;
    var bindings = options.bindings;
    bindings = bindings === undefined ? ConsoleBindings() : bindings;
    var debugging_mode = options.debug || (typeof debug == 'boolean' && debug);

    // Parsing and Run State.
    var labels = {};
    var data_labels = {};
    var flow = [];
    var types = {};
    var functions = {};
    var global_vars = {};
    var vars = global_vars;
    var allocated = 0;
    var const_count = 0;
    var temp_count = 0;
    var inside_type = false;
    var inside_function = false;
    var var_decls = '';
    var data = [];
    var data_pos = 0;
    var ops = [];
    var curop = '';
    var ip = 0;
    var function_define_pos = 0;
    var function_old_allocated = 0;
    var function_name = null;

    // Error handler state.
    var error_handler = Throw;
    var error_resume_point = null;

    // Yield State
    var yielding = 0;
    var quitting = 0;
    var delay = 0;

    // Call stack
    var stack = 0;
    var sp = 0;
    var bp = 0;

    // Language Options
    var option_base = 0;
    var option_explicit = false;

    // Variable declaration defaults.
    var letter_default = {};
    // Default is single.
    var i = 'a';
    do {
      letter_default[i] = 'single';
      i = NextChar(i);
    } while (i != 'z');

    const toklist = [
      ':', ';', ',', '(', ')', '{', '}', '[', ']',
      '+=', '-=', '*=', '/=', '\\=', '^=', '&=',
      '+', '-', '*', '/', '\\', '^', '&', '.',
      '<=', '>=', '<>', '=>', '=', '<', '>', '@', '\n',
    ];
    code = code.replace(/\r/g, ' ');
    code = code.replace(/\t/g, ' ');

    var tok = null;
    var tok_count = 0;
    var line = bindings.Render ? 0 : 1;

    function Next() {
      tok = '';
      tok_count++;
      for (;;) {
        while (code.substr(0, 1) == ' ' ||
               code.substr(0, 1) == '\t') {
          if (tok != '') {
            return;
          }
          code = code.substr(1);
        }
        if (code.search(/^_[ \t]*('[^\n]*)?\n/) != -1) {
          if (tok != '') {
            return;
          }
          code = code.substr(code.search('\n') + 1);
          ++line;
          continue;
        }
        if (code.substr(0, 1) == '\'') {
          if (tok != '') {
            return;
          }
          while (code.length > 0 && code.substr(0, 1) != '\n') {
            code = code.substr(1);
          }
          continue;
        }
        if (code.substr(0, 1) == '"') {
          if (tok != '') {
            return;
          }
          tok = '"';
          code = code.substr(1);
          while (code.length > 0 && code.substr(0, 1) != '"') {
            if (code.substr(0, 1) == '\n') {
              // Allow strings to cut off at end of line.
              // GW-Basic seems to allow it.
              tok += '"';
              return;
            }
            tok += code.substr(0, 1);
            code = code.substr(1);
          }
          tok += '"';
          code = code.substr(1);
          return;
        }
        if (tok == '' && /[.0-9][#]?/.test(code.substr(0, 1))) {
          var n = code.match(/^([0-9]*([.][0-9]*)?([eE][+-]?[0-9]+)?[#]?)/);
          if (n === null) {
            Error('Bad number');
          }
          tok = n[1];
          code = code.substr(tok.length);
          if (tok[tok.length - 1] == '#') {
            tok = tok.substr(0, tok.length - 1);
          }
          return;
        }
        for (var i = 0; i < toklist.length; ++i) {
          if (code.substr(0, toklist[i].length) == toklist[i]) {
            if (tok != '') {
              if (code.substr(0, 1) == '&' &&
                code.substr(code.length - 1) != '$') {
                tok += '&';
                code = code.substr(1);
              }
              return;
            }
            tok = toklist[i];
            code = code.substr(toklist[i].length);
            if (tok == '\n') {
              ++line;
              tok = '<EOL>';
            } else if (tok == '&' && code.substr(0, 1).toLowerCase() == 'h') {
              code = code.substr(1);
              var n = code.match(/^([0-9a-fA-F]+)/);
              if (n === null) {
                Error('Bad hex number');
              }
              tok = '0x' + n[1];
              code = code.substr(n[1].length);
            }
            return;
          }
        }
        tok += code.substr(0, 1).toLowerCase();
        code = code.substr(1);
        if (code == '') {
          return;
        }
      }
    }
    Next();

    function ConsumeData() {
      var quote = false;
      var had_quote = false;
      var item = '';
      for (;;) {
        var ch = code.substr(0, 1);
        if (ch == '\n' || ch == '') {
          if (!had_quote) {
            if (!quote) {
              item = item.trim();
            }
            data.push(item);
          }
          break;
        } else if (ch == '"') {
          if (quote) {
            data.push(item);
            item = '';
            quote = false;
            had_quote = true;
          } else {
            quote = true;
            if (item.search(/[^ \t]/) != -1) {
              Error('Data statement extra text: "' + item + '"');
            }
            item = '';
          }
        } else if (ch == ',') {
          if (!quote) {
            if (!had_quote) {
              data.push(item.trim());
            } else {
              had_quote = false;
              if (item.search(/[^ \t]/) != -1) {
                Error('Data statement extra text: "' + item + '"');
              }
            }
            item = '';
          } else {
            item += ',';
          }
        } else {
          item += ch;
        }
        code = code.substr(1);
      }
      Next();
    }

    function Error(msg, lineno) {
      if (lineno === undefined) {
        lineno = line;
      }
      error_resume_point = ip - 1;
      error_handler(msg + ' at line ' + lineno);
    }

    function ErrorGoto(target) {
      return function() {
        ip = target;
      };
    }

    function Resume0() {
      ip = error_resume_point;
      error_resume_point = null;
    }

    function ResumeNext() {
      ip = error_resume_point + 1;
      error_resume_point = null;
    }

    function Resume(target) {
      if (error_resume_point === null) {
        // Bypass error handler.
        Throw('RESUME without error');
      }
      error_resume_point = null;
      ip = target;
    }

    function Throw(msg) {
      throw msg;
    }

    function Skip(t) {
      if (tok != t) {
        Error('Expected "' + t + '" found "' + tok + '"');
      }
      Next();
    }

    function EndOfStatement() {
      return tok == ':' || tok == '<EOL>';
    }

    function SkipEndOfStatement() {
      if (!EndOfStatement()) {
        Error('Expected : or EOL');
      }
      Next();
    }

    function NewOp() {
      ops.push(curop);
      curop = '';
    }

    function If(e, n) {
      if (n === undefined) {
        n = [];
      }
      NewOp();
      ops[ops.length - 1] += 'if (!(' + e + ')) { ip = ';
      flow.push(['if', ops.length - 1, []]);
    }

    function Else() {
      var f = flow.pop();
      if (f[0] != 'if') {
        Error('ELSE unmatched to IF');
      }
      NewOp();
      var pos = ops.length - 1;
      ops[pos] += 'ip = ';
      NewOp();
      ops[f[1]] += ops.length + '; }\n';
      flow.push(['else', null, f[2].concat(pos)]);
    }

    function ElseIf(e) {
      var f = flow.pop();
      if (f[0] != 'if') {
        Error('ELSEIF unmatched to IF');
      }
      NewOp();
      var pos = ops.length - 1;
      ops[pos] += 'ip = ';
      NewOp();
      ops[f[1]] += ops.length + '; }\n';
      NewOp();
      ops[ops.length - 1] += 'if (!(' + e + ')) { ip = ';
      flow.push(['if', ops.length - 1, f[2].concat([pos])]);
    }

    function EndIf() {
      NewOp();
      var f = flow.pop();
      if (f[0] == 'else') {
        // nothing needed
      } else if (f[0] == 'if') {
        ops[f[1]] += ops.length + '; }\n';
      } else {
        Error('Unmatch end if');
      }
      for (var i = 0; i < f[2].length; ++i) {
        ops[f[2][i]] += ops.length + ';\n';
      }
    }

    function VarPtr(vname) {
      var vinfo;
      if (vars[vname] !== undefined) {
        vinfo = vars[vname];
      } else if (global_vars[vname] !== undefined) {
        vinfo = global_vars[vname];
      }
      if (vinfo === undefined) {
        Error('Undefined variable name');
      }
      if (vinfo.global) {
        return vinfo.offset;
      } else {
        return '(bp + ' + vinfo.offset + ')';
      }
    }

    function AddLabel(name) {
      if (labels[name] !== undefined) {
        Error('Label ' + name + ' defined twice');
      }
      NewOp();
      curop += '// LABEL ' + name + ':\n';
      labels[name] = ops.length;
      data_labels[name] = data.length;
    }

    function Factor3() {
      if (tok == '(') {
        Skip('(');
        var ret = Expression();
        Skip(')');
        return ret;
      } else {
        var name = tok;
        Next();
        if (name.substr(0, 1) == '"' ||
            /^[0-9]*([.][0-9]*)?([eE][+-]?[0-9]+)?$/.test(name) ||
            /^0x[0-9a-fA-F]+$/.test(name)) {
          return name;
        }
        if (name == 'rnd') {
          if (tok == '(') {
            Skip('(');
            if (tok != ')') {
              var e = Expression();
            }
            Skip(')');
          }
          return 'Math.random()';
        }
        if (name == 'varptr') {
          Skip('(');
          var vname = tok;
          Next();
          Skip(')');
          return VarPtr(vname);
        }
        if (name == 'stackdepth') {
          Skip('(');
          Skip(')');
          return 'sp';
        }
        if (name == 'basedepth') {
          Skip('(');
          Skip(')');
          return 'bp';
        }
        if (name == 'log' || name == 'ucase$' || name == 'lcase$' ||
            name == 'chr$' || name == 'sqr' ||
            name == 'int' || name == 'cint' || name == 'fix' ||
            name == 'asc' ||
            name == 'abs' || name == 'len' || name == 'val' ||
            name == 'cos' || name == 'sin' || name == 'tan' || name == 'atn' ||
            name == 'exp' || name == 'str$' || name == 'peek' ||
            name == 'ltrim$' || name == 'rtrim$' ||
            name == 'space$' || name == 'tab') {
          Skip('(');
          var e = Expression();
          Skip(')');
          switch (name) {
          case 'log': return 'Math.log(' + e + ')';
          case 'ucase$': return '(' + e + ').toUpperCase()';
          case 'lcase$': return '(' + e + ').toLowerCase()';
          case 'chr$': return 'String.fromCharCode(' + e + ')';
          case 'asc': return '(' + e + ').charCodeAt(0)';
          case 'sqr': return 'Math.sqrt(' + e + ')';
          case 'int': return 'Math.floor(' + e + ')';
          case 'cint': return 'Math.round(' + e + ')';
          case 'fix': return 'Math.trunc(' + e + ')';
          case 'abs': return 'Math.abs(' + e + ')';
          case 'cos': return 'Math.cos(' + e + ')';
          case 'sin': return 'Math.sin(' + e + ')';
          case 'tan': return 'Math.tan(' + e + ')';
          case 'atn': return 'Math.atan(' + e + ')';
          case 'exp': return 'Math.exp(' + e + ')';
          case 'str$': return 'ToString(' + e + ')';
          case 'val': return 'parseInt(' + e + ')';
          case 'peek': return 'Peek(' + e + ').toString()';
          case 'len': return '((' + e + ').length)';
          case 'ltrim$': return '((' + e + ').trimStart())';
          case 'rtrim$': return '((' + e + ').trimEnd())';
          case 'space$': return 'StringRep((' + e + '), " ")';
          case 'tab': return 'StringRep((' + e + '), "\t")';
          case 'stackdepth': return 'sp';
          }
          Error('This cannot happen');
        }
        if (name == 'atan2' || name == 'string$' ||
            name == 'left$' || name == 'right$' ||
            name == 'instr' || name == 'point') {
          Skip('(');
          var a = Expression();
          Skip(',');
          var b = Expression();
          Skip(')');
          if (name == 'atan2') {
            return 'Math.atan2(' + a + ', ' + b + ')';
          } else if (name == 'string$') {
            return 'StringRep(' + a + ', ' + b + ')';
          } else if (name == 'left$') {
            return '((' + a + ').substr(0, (' + b + ')))';
          } else if (name == 'right$') {
            return 'Right((' + a + '), (' + b + '))';
          } else if (name == 'instr') {
            return '((' + a + ').indexOf(' + b + ') + 1)';
          } else if (name == 'point') {
            return 'Point((' + a + '), (' + b + '))';
          } else {
            throw 'impossible';
          }
        }
        if (name == 'mid$' || name == 'seg$') {
          Skip('(');
          var a = Expression();
          Skip(',');
          var b = Expression();
          if (tok == ')') {
            Skip(')');
            return '((' + a + ').substr((' + b + ') - 1))';
          } else {
            Skip(',');
            var c = Expression();
            Skip(')');
            return '((' + a + ').substr((' + b + ') - 1, (' + c + ')))';
          }
        }
        if (name == 'inkey$') {
          return 'Inkey()';
        }
        if (name == 'timer') {
          return 'GetTimer()';
        }
        if (functions[name] !== undefined && !functions[name].is_subroutine) {
          return FunctionCall(name, {is_subroutine: false});
        }
        return IndexVariable(name);
      }
    }

    function Factor2() {
      var a = Factor3();
      while (tok == '^') {
        Next();
        var b = Factor3();
        a = 'Math.pow(' + a + ', ' + b + ')';
      }
      return a;
    }

    function Factor1() {
      var ret = '';
      while (tok == '+' || tok == '-') {
        ret += tok;
        Next();
      }
      return ret + '(' + Factor2() + ')';
    }

    function Factor() {
      var a = Factor1();
      while (tok == '*' || tok == '/') {
        var op = tok;
        Next();
        var b = Factor1();
        a = '(' + a + ')' + op + '(' + b + ')';
      }
      return a;
    }

    function Term2() {
      var a = Factor();
      while (tok == '\\') {
        Next();
        var b = Factor();
        a = 'Math.floor((' + a + ')/(' + b + '))';
      }
      return a;
    }

    function Term1() {
      var a = Term2();
      while (tok == 'mod') {
        Next();
        var b = Term2();
        a = '((' + a + ')%(' + b + '))';
      }
      return a;
    }

    function Term() {
      var a = Term1();
      while (tok == '+' || tok == '-') {
        var op = tok;
        Next();
        var b = Term1();
        a = '(' + a + ')' + op + '(' + b + ')';
      }
      return a;
    }

    function Relational() {
      var a = Term();
      while (tok == '=' || tok == '<' || tok == '>' ||
             tok == '<>' || tok == '<=' || tok == '>=' || tok == '=>') {
        var op = tok;
        Next();
        if (op == '=>') {
          op = '>=';
        }
        var b = Term();
        if (op == '=') {
          a = '(' + a + ') == (' + b + ') ? -1 : 0';
        } else if (op == '<>') {
          a = '(' + a + ') != (' + b + ') ? -1 : 0';
        } else {
          a = '(' + a + ') ' + op + ' (' + b + ') ? -1 : 0';
        }
      }
      return a;
    }

    function Logical1() {
      var ret = '';
      while (tok == 'not') {
        Next();
        ret += '~';
      }
      return ret + '(' + Relational() + ')';
    }

    function Logical() {
      var a = Logical1();
      while (tok == 'and') {
        Next();
        var b = Logical1();
        a = '(' + a + ') & (' + b + ')';
      }
      return a;
    }

    function Expression() {
      var a = Logical();
      while (tok == 'or') {
        Next();
        var b = Logical();
        a = '(' + a + ') | (' + b + ')';
      }
      return a;
    }

    function TypeName() {
      if (SIMPLE_TYPE_INFO[tok]) {
        var type = tok;
        Next();
        return type;
      } else if (tok == 'integer') {
        Skip('integer');
        return 'long';
      } else if (tok == 'any') {
        Skip('any');
        // TODO: Handle this properly.
        return 'string';
      } else if (types[tok] !== undefined) {
        var type_name = tok;
        if (types[type_name] === undefined) {
          Error('Undefined type');
        }
        Next();
        return type_name;
      }
      Error('Undefined type "' + tok + '"');
    }

    function ImplicitType(name) {
      return IMPLICIT_TYPE_MAP[name[name.length - 1]] ||
        letter_default[name[0]] || 'single';
    }

    function Align(alignment) {
      allocated = Math.floor((allocated + alignment - 1) /
          alignment) * alignment;
    }

    function Allocate(size) {
      Align(size > 8 ? 8 : size);
      var ret = allocated;
      allocated += size;
      return ret;
    }

    function DimScalarVariable(name, type_name, defaults) {
      var info = types[type_name] || SIMPLE_TYPE_INFO[type_name];
      if (info === undefined) {
        Error('Unknown type');
      }
      var size = info.size;
      var offset = Allocate(size);
      vars[name] = {
        offset: offset,
        dimensions: 0,
        type_name: type_name,
        global: vars === global_vars,
      };
      if (inside_type) {
        var_decls += '//   field ' + name + ' is at ' + offset + '\n';
      } else if (vars[name].global) {
        var_decls += '// ' + name + ' is at ' + offset + '\n';
      } else {
        if (inside_function) {
          curop += '//   ' + name + ' is at (bp + ' + offset + ')\n';
        } else {
          var_decls += '//   ' + name + ' is at (bp + ' + offset + ')\n';
        }
      }
      if (defaults.length > 0) {
        curop += IndexVariable(name, true) + ' = ' + defaults[0] + ';\n';
      }
    }

    function MaybeImplicitDimVariable(name, argument_to_function) {
      // TODO: Handle array variables.
      if (argument_to_function &&
          argument_to_function.vars[name] !== undefined) {
        return argument_to_function.vars[name];
      }
      if (vars[name] !== undefined) {
        return vars[name];
      }
      if (global_vars[name] !== undefined) {
        return global_vars[name];
      }
      if (option_explicit) {
        Error('Undeclared variable ' + name);
      }
      var type_name = ImplicitType(name);
      DimScalarVariable(name, type_name, []);
      return vars[name];
    }

    function ArrayPart(offset, i) {
      return SIMPLE_TYPE_INFO['long'].view +
        '[((' + offset + '>>2)+' + i + ')]';
    }

    function ReserveArrayCell(name) {
      if (vars[name] === undefined &&
          global_vars[name] == undefined) {
        var offset = Allocate(4 + MAX_DIMENSIONS * 4 * 2);
        vars[name] = {
          offset: offset,
          dimensions: null,
          type_name: null,
          global: vars === global_vars,
        };
        var boffset = offset;
        if (!vars[name].global) {
          boffset = '(bp+' + boffset + ')';
        }
        var_decls += '// ' + name + ' is at ' + ArrayPart(boffset, 0) +
          ' (cell-addr: ' + offset + ')\n';
      }
      if (vars[name] !== undefined) {
        return vars[name];
      }
      return global_vars[name];
    }

    function ImplicitDimArray(name) {
      var dimensions = [[option_base, 10]];
      DimArrayVariable(name, ImplicitType(name), false, dimensions, []);
    }

    function DimArrayVariable(
      name, type_name, is_declare, dimensions, defaults) {
      if (dimensions.length > MAX_DIMENSIONS) {
        Error('Too many dimensions');
      }
      var offset = ReserveArrayCell(name).offset;
      var info = types[type_name] || SIMPLE_TYPE_INFO[type_name];
      var parts = [];
      for (var i = 0; i < dimensions.length; i++) {
        parts.push('((' + dimensions[i][1] + ')-(' + dimensions[i][0] + ')+1)');
      }
      if (!is_declare) {
        if (!vars[name].global) {
          offset = '(bp+' + offset + ')';
        }
        curop += '// Allocate ' + name + '\n';
        curop += 'if (' + ArrayPart(offset, 0) + ' === 0) {\n';
        curop += '  ' + ArrayPart(offset, 0) + ' = Allocate(' +
          [info.size].concat(parts).join('*') + ');\n';
        for (var i = 0; i < dimensions.length; i++) {
          curop += '  ' + ArrayPart(offset, i * 2 + 1) + ' = ' +
            dimensions[i][0] + ';\n';
          curop += '  ' + ArrayPart(offset, i * 2 + 2) + ' = ' +
            [info.size].concat(parts).slice(0, i + 1).join('*') + ';\n';
        }
        if (defaults.length > 0) {
          if (dimensions.length > 1) {
            Error('Only 1-d array defaults supported');
          }
          if (!SIMPLE_TYPE_INFO[type_name]) {
            Error('Only simple type array defaults supported');
          }
          for (var i = 0; i < defaults.length; i++) {
            curop += '  ' + info.view + '[' +
              ' + (' + ArrayPart(offset, 0) + ' >> ' + info.shift + ') + '
              + i + '] = (' + defaults[i] + ');\n';
          }
        }
        curop += '}\n';
        NewOp();
      }
      vars[name] = {
        offset: offset,
        dimensions: dimensions.length > 0 ? dimensions.length : -1,
        type_name: type_name,
        global: vars === global_vars,
      };
    }

    function DimVariable(default_tname, redim, is_declare) {
      var name = tok;
      Next();
      // Pick default.
      if (default_tname === null) {
        default_tname = ImplicitType(name);
      }
      var type_name = default_tname;
      var dimensions = [];
      var defaults = [];
      var is_scalar = true;
      if (tok == '(') {
        Skip('(');
        is_scalar = false;
        while (tok != ')') {
          var e = Expression();
          var d = 'dim' + const_count++;
          var_decls += 'const ' + d + ' = (' + e + ');\n';
          if (tok == 'to') {
            Skip('to');
            var e1 = Expression();
            var d1 = 'dim' + const_count++;
            var_decls += 'const ' + d1 + ' = (' + e1 + ');\n';
            dimensions.push([d, d1]);
          } else {
            dimensions.push([option_base, d]);
          }
          if (tok != ',') {
            break;
          }
          Skip(',');
        }
        Skip(')');
        if (tok == '=') {
          Skip('=');
          Skip('{');
          var e = Expression();
          defaults.push(e);
          while (tok == ',') {
            Skip(',');
            var e = Expression();
            defaults.push(e);
          }
          Skip('}');
        }
      } else if (tok == '=') {
        Skip('=');
        var e = Expression();
        defaults.push(e);
      }
      if (tok == 'as') {
        Skip('as');
        type_name = TypeName();
      }
      if (vars[name] !== undefined && vars[name].dimensions != null) {
        if (redim) {
          return;
        }
        Error('Variable ' + name + ' defined twice');
      }
      if (is_scalar) {
        DimScalarVariable(name, type_name, defaults);
      } else {
        DimArrayVariable(name, type_name, is_declare, dimensions, defaults);
      }
    }

    function Invoke(name, kind_vals) {
      var kind = kind_vals[0];
      var vals = kind_vals[1];
      curop += 'var t = ' + name + '(';
      var pos = 0;
      for (var i = 0; i < kind.length; i++) {
        var k = kind.charAt(i);
        var kl = k.toLowerCase();
        if (kl == 'i' || kl == 's' || kl == 'p' || kl == 'v') {
          if (pos != 0) {
            curop += ', ';
          }
          if (kl == 'p') {
            curop += vals[i][0];
            curop += ', ';
            curop += vals[i][1];
          } else if (kl == 'v') {
            curop += 'buffer, ';
            curop += vals[i];
          } else {
            curop += vals[i];
          }
          pos++;
        }
      }
      curop += ');';
      pos = 0;
      for (var i = 0; i < kind.length; i++) {
        var k = kind.charAt(i);
        if (k == 'o' || k == 'O') {
          if (vals[i] !== undefined) {
            curop += '  ' + vals[i] + ' = t[' + pos + '];';
          }
          pos++;
        }
      }
      curop += '\n';
    }

    function ParenArguments(kind) {
      if (kind.length == 0) {
        return [[], []];
      }
      Skip('(');
      var ret = Arguments(kind);
      Skip(')');
      return ret;
    }

    function Arguments(kind) {
      // i - input / I - optional input
      // o - output / O - optional output
      // p - point (x, y) / P - optional point (passes 2 values)
      // s - string flag / S - optional string flag (e.g. BF for LINE)
      // d - dash (e.g. in words like LINE)
      // v - varptr (e.g. in words list GET / PUT, passes buffer, offset)
      var ret = [];
      for (var i = 0; i < kind.length; i++) {
        var k = kind.charAt(i);
        if (k == 'I' || k == 'O' || k == 'P' || k == 'S') {
          if (tok == ')' || tok == ',' || EndOfStatement()) {
            if (k == 'P') {
              ret.push([undefined, undefined]);
            } else {
              ret.push(undefined);
            }
            if (tok == ',') {
              Skip(',');
            }
            continue;
          }
        }
        if (k == 'o' || k == 'O') {
          ret.push(GetVar());
        } else if (k == 'i' || k == 'I') {
          ret.push(Expression());
        } else if (k == 's' || k == 'S') {
          ret.push('"' + tok + '"');
          Next();
        } else if (k == 'p' || k == 'P') {
          Skip('(');
          var x = Expression();
          Skip(',');
          var y = Expression();
          Skip(')');
          ret.push([x, y]);
        } else if (k == 'd') {
          Skip('-');
          ret.push(undefined);
        } else if (k == 'v') {
          var name = tok;
          Next();
          ret.push(ArrayPart(ReserveArrayCell(name).offset, 0));
        } else {
          Error('Bad binding');
        }
        if (tok == ',' && i != kind.length - 1) {
          Skip(',');
        }
      }
      return [kind, ret];
    }

    function IndexVariable(name, assignable, argument_to_function) {
      var v = MaybeImplicitDimVariable(name, argument_to_function);
      var offset = v.offset;
      if (!v.global) {
        if (argument_to_function) {
          offset = '(sp+' + offset + ')';
        } else {
          offset = '(bp+' + offset + ')';
        }
      }
      var type_name = v.type_name;
      while (!argument_to_function && (tok == '(' || tok == '.')) {
        if (tok == '(') {
          Skip('(');
          var dims = [];
          while (tok != ')') {
            var e = Expression();
            dims.push(e);
            if (tok != ',') {
              break;
            }
            Skip(',');
          }
          Skip(')');
          var info = types[type_name] || SIMPLE_TYPE_INFO[type_name];
          // Extra indirection for array parameter access.
          if (v.dimensions === -1) {
            offset = 'i[' + offset + ']';
          }
          var noffset = '(';
          noffset += ArrayPart(offset, 0) + ' + (';
          if (v.dimensions !== -1 && dims.length != v.dimensions) {
            ImplicitDimArray(name);
            // TODO: This is sus.
            //Error('Array dimension expected ' + v.dimensions +
            //      ' but found ' + dims.length + ', array named: ' + name);
          }
          for (var i = 0; i < dims.length; ++i) {
            noffset += '(((' + dims[i] + ')|0)-' +
                ArrayPart(offset, i * 2 + 1) + ')';
            noffset += '*' + ArrayPart(offset, i * 2 + 2);
            if (i != dims.length - 1) {
              noffset += '+';
            }
          }
          noffset += '))';
          offset = noffset;
        } else if (tok == '.') {
          Skip('.');
          v = types[type_name];
          if (v === undefined) {
            Error('Not a struct type');
          }
          var field = v.vars[tok];
          if (field === undefined) {
            Error('Invalid field name');
          }
          Next();
          offset = '(' + offset + ' + ' + field.offset + ')';
          type_name = field.type_name;
        }
      }
      var info = SIMPLE_TYPE_INFO[type_name];
      if (!info) {
        Error('Expected simple type');
      }
      var vname = info.view + '[' + offset + '>>' + info.shift + ']';
      if (info.view == 'str' && assignable === undefined) {
        vname = '((' + vname + ')||"")';
      }
      return vname;
    }

    function FunctionDefine(options) {
      var name = tok;
      Next();
      if (vars !== global_vars) {
        Error('Nested SUB/FUNCTION not allowed');
      }
      if (functions[name] !== undefined && !functions[name].is_declaration) {
        Error('SUB/FUNCTION already defined: ' + name);
      }
      NewOp();
      var pos = ops.length - 1;
      var parameters = [];
      var old_allocated = allocated;
      allocated = 0;
      vars = {};
      var nfunc = {
        vars: vars,
        parameters: parameters,
        ip: ops.length,
        allocation: -1,
        is_subroutine: options.is_subroutine || false,
        is_declaration: options.is_declaration || false,
      };
      if (nfunc.is_declaration) {
        if (nfunc.is_subroutine) {
          var_decls += '// SUB ' + name + '\n';
        } else {
          var_decls += '// FUNCTION ' + name + '\n';
        }
      } else {
        if (nfunc.is_subroutine) {
          curop += '// SUB ' + name + '\n';
        } else {
          curop += '// FUNCTION ' + name + '\n';
        }
      }
      if (!nfunc.is_declaration) {
        inside_function = true;
      }
      DimScalarVariable(name, ImplicitType(name), []);
      // In case return value gets redefined.
      Align(8);
      if (tok == '(') {
        Skip('(');
        if (tok != ')') {
          parameters.push(tok);
          DimVariable(null, undefined, true);
          while (tok == ',') {
            Skip(',');
            parameters.push(tok);
            DimVariable(null, undefined, true);
          }
        }
        Skip(')');
        Align(8);
      }
      nfunc.allocation = allocated;
      if (options.is_declaration) {
        vars = global_vars;
        allocated = old_allocated;
        if (functions[name] == undefined) {
          functions[name] = nfunc;
        } else {
          // TODO: Check for declaration mismatch in type.
          if (functions[name].parameters.length != nfunc.parameter.length) {
            Error('DECLARE and definition parameters do not match');
          }
        }
      } else {
        function_old_allocated = old_allocated;
        function_define_pos = pos;
        function_name = name;
        functions[name] = nfunc;
      }
      if (tok == 'as') {
        Skip('as');
        var type_name = TypeName();
        if (!SIMPLE_TYPE_INFO[type_name]) {
          Error('Expected basic type');
        }
        functions[name].type_name = type_name;
      }
      if (tok == 'static') {
        Skip('static');
        // TODO: Implement.
      }
    }

    function FunctionExit() {
      if (vars === global_vars) {
        Error('SUB/FUNCTION EXIT only allowed inside SUB/FUNCTION.');
      }
      curop += 'sp -= 8; ip = i[sp>>2];\n';
      NewOp();
    }

    function FunctionEnd() {
      if (vars === global_vars) {
        Error('SUB/FUNCTION END only allowed at end of SUB/FUNCTION.');
      }
      inside_function = false;
      FunctionExit();
      ops[function_define_pos] += 'ip = ' + ops.length + ';\n';
      vars = global_vars;
      Align(8);
      functions[function_name].allocation = allocated;
      function_name = null;
      allocated = function_old_allocated;
    }

    function FunctionCall(name, options) {
      var func = functions[name];
      if (func === undefined || options.is_subroutine !== func.is_subroutine) {
        if (options.is_subroutine) {
          Error('Expected valid subroutine name, found: ' + name);
        } else {
          Error('Expected valid function name, found: ' + name);
        }
      }
      curop += 'i[sp>>2] = bp; sp += 8;\n';
      var has_parens = tok == '(' || func.parameters.length != 0;
      if (options.is_call || (!options.is_subroutine && has_parens)) {
        Skip('(');
      }
      var args = [];
      for (var i = 0; i < func.parameters.length; ++i) {
        if (func.vars[func.parameters[i]].dimensions == -1) {
          var vname = tok;
          Next();
          Skip('(');
          Skip(')');
          args.push(null);
          curop += 'i[sp + ' + func.vars[func.parameters[i]].offset + '] = ' +
            VarPtr(vname) + ';\n';
        } else {
          var old_tok_count = tok_count;
          var old_tok = tok;
          var e = Expression();
          curop += IndexVariable(func.parameters[i], true, func) +
            ' = ' + e + ';\n';
          if (vars[old_tok] && tok_count - old_tok_count == 1) {
            args.push(old_tok);
          } else {
            args.push(null);
          }
        }
        if (i != func.parameters.length - 1) {
          Skip(',');
        }
      }
      if (options.is_call || (!options.is_subroutine && has_parens)) {
        Skip(')');
      }
      // Blank return value.
      if (!options.is_subroutine) {
        curop += IndexVariable(name, true, func) + ' = 123;\n';
      }
      curop += 'bp = sp;\n';
      curop += 'sp += functions["' + name + '"].allocation;\n';
      curop += 'i[sp>>2] = ip; sp += 8;\n';
      curop += 'ip = functions["' + name + '"].ip;\n';
      NewOp();
      // TODO: Types?
      curop += 'sp -= functions["' + name + '"].allocation;\n';
      curop += 'bp = i[(sp-8)>>2];\n';
      var temp = '#temp' + temp_count;
      if (!options.is_subroutine) {
        ++temp_count;
        DimScalarVariable(temp, func.vars[name].type_name, []);
        curop += IndexVariable(temp, true) +
          ' = ' + IndexVariable(name, false, func) + ';\n';
      }
      for (var i = 0; i < args.length; ++i) {
        if (args[i]) {
          curop += IndexVariable(args[i], true) + ' = ' +
            IndexVariable(func.parameters[i], false, func) + ';\n';
        }
      }
      curop += 'sp -= 8;\n';
      if (!options.is_subroutine) {
        return IndexVariable(temp, false);
      }
    }

    function StringRep(n, ch) {
      var ret = '';
      var cch;
      if (typeof ch == 'string') {
        cch = ch;
      } else {
        cch = String.fromCharCode(ch);
      }
      for (var i = 0; i < n; ++i) {
        ret += cch;
      }
      return ret;
    }

    function ToString(s) {
      if (s < 0) {
        return s.toString();
      } else {
        return ' ' + s.toString();
      }
    }

    function GetVar() {
      var name = tok;
      Next();
      return IndexVariable(name, true);
    }

    var DEFAULT_TYPES = {
      'defdbl': 'double',
      'defsng': 'single',
      'defint': 'short',
      'deflng': 'long',
      'defstr': 'string',
    };

    function Statement() {
      if (EndOfStatement()) {
        // Ignore empty lines.
      } else if (tok == 'rem') {
        do {
          Next();
        } while (tok != '<EOL>');
      } else if (tok == 'if') {
        Skip('if');
        var e = Expression();
        Skip('then');
        if (EndOfStatement()) {
          If(e);
          while (tok == ':') {
            Skip(':');
            Statement();
          }
          if (tok == 'else') {
            Skip('else');
            Else();
            while (tok == ':') {
              Skip(':');
              Statement();
            }
          }
          if (tok == 'end') {
            Skip('end');
            Skip('if');
            EndIf();
          }
        } else {
          // Classic if <e> then
          If(e);
          if (tok.match(/^[0-9]+$/)) {
            var name = tok;
            Next();
            curop += 'ip = labels["' + name + '"];\n';
            NewOp();
          } else {
            Statement();
            while (tok == ':') {
              Skip(':');
              Statement();
            }
          }
          var f = flow.pop();
          if (f[0] != 'if') {
            Error('If in mixed style');
          }
          flow.push(f);
          NewOp();
          if (tok == 'else') {
            Skip('else');
            Else();
            // TI style else.
            if (tok.match(/^[0-9]+$/)) {
              var name = tok;
              Next();
              curop += 'ip = labels["' + name + '"];\n';
              NewOp();
              EndIf();
              return;
            }
            Statement();
            while (tok == ':') {
              Skip(':');
              Statement();
            }
          }
          EndIf();
        }
      } else if (tok == 'elseif') {
        Skip('elseif');
        var e = Expression();
        Skip('then');
        ElseIf(e);
      } else if (tok == 'else') {
        Skip('else');
        Else();
        if (!EndOfStatement()) {
          Statement();
        }
      } else if (tok == 'do') {
        Skip('do');
        if (tok == 'while') {
          // Support DO WHILE
          Statement();
          return;
        }
        NewOp();
        flow.push(['do', ops.length]);
      } else if (tok == 'loop') {
        Skip('loop');
        var is_while;
        if (tok == 'while') {
          Skip('while');
          is_while = true;
        } else if (tok == 'until') {
          Skip('until');
          is_while = false;
        } else if (EndOfStatement()) {
          var f = flow.pop();
          if (f[0] != 'while' && f[0] != 'do') {
            Error('LOOP does not match DO / WHILE');
          }
          curop += 'ip = ' + f[1] + ';\n';
          NewOp();
          if (f[0] == 'while') {
            ops[f[1]] += ops.length + '; }\n';
          }
          return;
        } else {
          Error('Expected while/until');
        }
        var e = Expression();
        var f = flow.pop();
        if (f[0] != 'do') {
          Error('LOOP does not match DO');
        }
        if (is_while) {
          curop += 'if (' + e + ') { ip = ' + f[1] + '; }\n';
        } else {
          curop += 'if (!(' + e + ')) { ip = ' + f[1] + '; }\n';
        }
        NewOp();
      } else if (tok == 'while') {
        Skip('while');
        var e = Expression();
        NewOp();
        curop += 'if (!(' + e + ')) { ip = ';
        NewOp();
        flow.push(['while', ops.length - 1]);
      } else if (tok == 'wend') {
        Skip('wend');
        var f = flow.pop();
        if (f[0] != 'while') {
          Error('Wend does not match while');
        }
        curop += 'ip = ' + f[1] + ';\n';
        NewOp();
        ops[f[1]] += ops.length + '; }\n';
      } else if (tok == 'exit') {
        Skip('exit');
        if (tok == 'sub') {
          Skip('sub');
          FunctionExit();
        } else if (tok == 'function') {
          Skip('function');
          FunctionExit();
        } else {
          Error('Expected sub/function');
        }
      } else if (tok == 'end') {
        Skip('end');
        if (tok == 'if') {
          Skip('if');
          EndIf();
        } else if (tok == 'select') {
          Skip('select');
          NewOp();
          var f = flow.pop();
          if (f[0] != 'select') {
            Error('end select outside select');
          }
          var disp = 'var t = (' + f[1] + ');\n';
          disp += 'if (false) {}\n';
          for (var i = 0; i < f[3].length; i++) {
            var ii = f[3][i];
            if (ii[0] == ii[1]) {
              disp += 'else if (t == (' + ii[0] +
                      ')) { ip = ' + ii[2] + '; }\n';
            } else {
              disp += 'else if (t >= (' + ii[0] + ') && t <= (' + ii[1] +
                      ')) { ip = ' + ii[2] + '; }\n';
            }
          }
          if (f[5] !== null) {
            disp += 'else { ip = ' + f[5] + '; }\n';
          } else {
            disp += 'else { ip = ' + ops.length + '; }\n';
          }
          ops[f[2]] += disp;
          for (var i = 0; i < f[4].length; i++) {
            ops[f[4][i]] += 'ip = ' + ops.length + ';\n';
          }
        } else if (tok == 'sub') {
          Skip('sub');
          FunctionEnd();
        } else if (tok == 'function') {
          Skip('function');
          FunctionEnd();
        } else {
          curop += 'End();\n';
        }
      } else if (tok == 'goto') {
        Skip('goto');
        var name = tok;
        Next();
        curop += 'ip = labels["' + name + '"];\n';
        NewOp();
      } else if (tok == 'gosub') {
        Skip('gosub');
        var name = tok;
        Next();
        curop += 'i[sp>>2] = ip; sp += 8;\n';
        curop += 'ip = labels["' + name + '"];\n';
        NewOp();
      } else if (tok == 'return') {
        Skip('return');
        curop += 'sp -= 8; ip = i[sp>>2];\n';
        NewOp();
      } else if (tok == 'declare') {
        Skip('declare');
        if (tok == 'sub') {
          Skip('sub');
          FunctionDefine({is_subroutine: true, is_declaration: true});
        } else if (tok == 'function') {
          Skip('function');
          FunctionDefine({is_subroutine: false, is_declaration: true});
        } else {
          Error('Unexpected declaration');
        }
      } else if (tok == 'type') {
        var old_allocated = allocated;
        vars = {};
        Skip('type');
        var type_name = tok;
        Next();
        if (types[type_name] !== undefined) {
          Error('Duplicate type definition');
        }
        types[type_name] = {
          vars: vars,
          size: 0,
        };
        inside_type = true;
        var_decls += '// TYPE ' + type_name + '\n';
        SkipEndOfStatement();
        while (tok != 'end') {
          while (!EndOfStatement()) {
            DimVariable(null);
            while (tok == ',') {
              Skip(',');
              DimVariable(null);
            }
          }
          SkipEndOfStatement();
        }
        Skip('end');
        Skip('type');
        inside_type = false;
        types[type_name].size = allocated;
        vars = global_vars;
        allocated = old_allocated;
      } else if (tok == 'const') {
        Skip('const');
        // TODO: Enforce consts are const.
        for (;;) {
          var name = tok;
          Next();
          var v = vars[name];
          if (v !== undefined) {
            Error('Constant ' + name + ' defined twice');
          }
          var offset = Allocate(8);
          vars[name] = {
            offset: offset,
            type_name: 'double',
            global: vars === global_vars,
          };
          v = vars[name];
          Skip('=');
          var value = Expression();
          var_decls += SIMPLE_TYPE_INFO['double'].view +
            '[' + (offset >> 3) + ']' +
            ' = (' + value + ');  // ' + name + '\n';
          if (tok == ',') {
            Skip(',');
            continue;
          }
          break;
        }
      } else if (tok == 'dim' || tok == 'redim') {
        var op = tok;
        Next();
        if (tok == 'shared') {
          Skip('shared');
        }
        var tname = null;
        if (tok == 'as') {
          Skip('as');
          tname = TypeName();
        }
        DimVariable(tname, op == 'redim');
        while (tok == ',') {
          Skip(',');
          DimVariable(tname, op == 'redim');
        }
      } else if (tok == 'error') {
        Skip('error');
        var e = Expression();
        curop += 'Error("Error " + ' + e + ', ' + line + ');\n';
        NewOp();
      } else if (tok == 'on') {
        Skip('on');
        if (tok == 'error') {
          Skip('error');
          if (tok == 'goto') {
            Skip('goto');
            if (tok == '0') {
              curop += 'error_handler = Throw;\n';
              Next();
              NewOp();
            } else {
              curop += 'error_handler = ErrorGoto(labels["' + tok + '"]);\n';
              Next();
              NewOp();
            }
          } else if (tok == 'resume') {
            Skip('resume');
            Skip('next');
            curop += 'error_handler = (function() {});\n';
            NewOp();
          } else {
            Error('Expected goto / resume next.');
          }
        } else {
          var name = Expression();
          if (tok == 'goto' || tok == 'gosub') {
            var isGosub = (tok == 'gosub');
            Next();
            if (EndOfStatement()) {
              Error('Expected labels.');
            }
            if (isGosub) {
              curop += 'i[sp>>2] = ip; sp += 8;\n';
            }
            curop += 'ip = labels[[';
            while (!(EndOfStatement())) {
              curop += '"' + tok + '"';
              Next();
              if (EndOfStatement()) {
                if (isGosub) {
                  curop += '][((' + name + ')|0) - 1]];\n';
                  curop += 'if(ip == undefined){ sp -= 8; ip = i[sp>>2]; }\n';
                } else {
                  curop += '][((' + name + ')|0) - 1]] || ip;\n';
                }
              } else {
                curop += tok;
                Skip(',');
              }
            }
          } else {
            Error('Expected GOTO or GOSUB. Found ' + tok);
          }
          NewOp();
        }
      } else if (tok == 'resume') {
        Skip('resume');
        if (tok == 'next') {
          Skip('next');
          curop += 'ResumeNext();\n';
          NewOp();
        } else if (tok == '0') {
          Skip('0');
          curop += 'Resume0();\n';
          NewOp();
        } else {
          curop += 'Resume(labels["' + String(tok) + '"]);\n';
          Next();
          NewOp();
        }
      } else if (tok == 'sub') {
        Skip('sub');
        FunctionDefine({is_subroutine: true});
      } else if (tok == 'function') {
        Skip('function');
        FunctionDefine({is_subroutine: false});
      } else if (tok == 'def') {
        Skip('def');
        if (tok == 'seg') {
          Skip('seg');
          if (tok == '=') {
            Skip('=');
            var e = Expression();
            // TODO: Do something useful with it?
          }
        } else if (tok.substr(0, 2) == 'fn') {
          var fname = tok;
          var pos = FunctionDefine({is_subroutine: false});
          Skip('=');
          var e = Expression();
          curop += IndexVariable(fname, true) + ' = ' + e + ';\n';
          FunctionEnd(pos);
        } else {
          Error('Expected SEG/FNxxx');
        }
      } else if (tok == 'open') {
        Skip('open');
        var filename = Expression();
        Skip('for');
        if (tok == 'input') {
          Skip('input');
        } else if (tok == 'output') {
          Skip('output');
        } else {
          Error('Expected input/output');
        }
        Skip('as');
        Next();
        // TODO: Implement.
      } else if (tok == 'close') {
        Skip('close');
        if (!EndOfStatement()) {
          // #n
          Next();
        }
        // TODO: Implement.
      } else if (tok == 'system') {
        Skip('system');
        // TODO: Implement.
      } else if (tok == 'beep') {
        Skip('beep');
        // TODO: Implement.
      } else if (tok == 'view') {
        Skip('view');
        if (tok == 'print') {
          Skip('print');
          if (!EndOfStatement()) {
            var top = Expression();
            Skip('to');
            var bottom = Expression();
          }
          // TODO: Implement.
        } else if (tok == 'screen') {
          Skip('screen');
          // TODO: Implement.
        } else {
          Error('Expected PRINT/SCREEN');
        }
      } else if (tok == 'randomize') {
        Skip('randomize');
        if (!EndOfStatement()) {
          var seed = Expression();
          // TODO: Implement seed handling.
        }
      } else if (tok == 'poke') {
        Skip('poke');
        var addr = Expression();
        Skip(',');
        var value = Expression();
        // TODO: Do something useful with it?
      } else if (tok == 'key') {
        Skip('key');
        if (tok == 'on') {
          Skip('on');
        } else if (tok == 'off') {
          Skip('off');
        } else {
          Error('Expected on/off');
        }
        // Implement this?
      } else if (tok == 'chain') {
        Skip('chain');
        var filename = Expression();
        if (tok == ',') {
          Skip(',');
          var name = tok;
          Next();
        }
        // TODO: Implement this.
      } else if (tok == 'option') {
        Skip('option');
        if (tok == 'explicit') {
          Skip('explicit');
          option_explicit = true;
        } else if (tok == 'base') {
          Skip('base');
          if (tok == '0') {
            option_base = 0;
          } else if (tok == '1') {
            option_base = 1;
          } else {
            Error('Unexpected option base "' + tok + '"');
          }
          Next();
        } else {
          Error('Unexpected option "' + tok + '"');
        }
      } else if (tok == 'defdbl' || tok == 'defsng' || tok == 'deflng' ||
                 tok == 'defint' || tok == 'defstr') {
        var def_type = tok;
        Next();
        for (;;) {
          var start = tok;
          Next();
          Skip('-');
          var end = tok;
          Next();
          if (!start.match(/^[a-z]$/) ||
              !end.match(/^[a-z]$/) ||
              start.charCodeAt(0) > end.charCodeAt(0)) {
            Error('Invalid variable range');
          }
          var i = start;
          do {
            letter_default[i] = DEFAULT_TYPES[def_type];
            i = NextChar(i);
          } while (i != end);
          if (tok == ',') {
            Skip(',');
            continue;
          }
          break;
        }
      } else if (tok == 'for') {
        Skip('for');
        var name = tok;
        var v = IndexVariable(name, true);
        Next();
        Skip('=');
        var start = Expression();
        Skip('to');
        var end = Expression();
        var step = 1;
        if (tok == 'step') {
          Skip('step');
          step = Expression();
        }
        curop += v + ' = (' + start + ');';
        NewOp();
        curop += 'if (((' + step + ' > 0) && ' +
                      v + ' > (' + end + ')) || ' +
                     '((' + step + ' < 0) && ' +
                      v + ' < (' + end + '))) { ip = ';
        NewOp();
        flow.push(['for', v, ops.length - 1, step]);
      } else if (tok == 'next') {
        Skip('next');
        var f = flow.pop();
        if (f[0] != 'for') {
          Error('Expected NEXT');
        }
        if (!EndOfStatement()) {
          var name = tok;
          // TODO: Shouldn't this fail?
          /*
          if (name != f[1]) {
            Error('Expected ' + f[1]);
          }
          */
          Next();
        }
        curop += f[1] + ' += (' + f[3] + ');\n';
        curop += 'ip = ' + f[2] + ';\n';
        NewOp();
        ops[f[2]] += ops.length + '; }\n';
      } else if (tok == 'mid$') {
        Skip('mid$');
        Skip('(');
        var a = GetVar();
        Skip(',');
        var x = Expression();
        var y = '(' + a + '.length)';
        if (tok == ')') {
          Skip(')');
        } else {
          Skip(',');
          y = Expression();
          Skip(')');
        }
        Skip('=');
        var z = Expression();
        curop += a + ' = MidReplace(' + a + ', ' + x + ', ' +
                 y + ', ' + z + ');\n'
      } else if (tok == 'line') {
        Skip('line');
        if (tok == 'input') {
          Skip('input');
          if (tok == ';') {
            Skip(';');
          }
          var prompt = '""';
          if (tok.substr(0, 1) == '"') {
            var prompt = tok;
            Next();
            if (tok == ';' || tok == ',') {
              Next();
            }
          }
          curop += 'Print([' + prompt + ', ";"]);\n';
          curop += 'PutCh(String.fromCharCode(219));\n';
          curop += 'LineClear();\n';
          NewOp();
          curop += 'ip += LineInput();\n';
          NewOp();
          var a = GetVar();
          curop += a + ' = LineValue();\n';
          return;
        }
        Invoke('Line', Arguments('PdpIS'));
      } else if (tok == 'sleep') {
        Next();
        Invoke('Sleep', Arguments('i'));
        NewOp();
      } else if (tok == 'swap') {
        Skip('swap');
        var a = GetVar();
        Skip(',');
        var b = GetVar();
        curop += 'var t = ' + a + ';\n';
        curop += a + ' = ' + b + ';\n';
        curop += b + ' = t;\n';
      } else if (tok == 'data') {
        ConsumeData();
      } else if (tok == 'read') {
        Skip('read');
        curop += GetVar() + ' = Read();\n';
        while (tok == ',') {
          Skip(',');
          curop += GetVar() + ' = Read();\n';
        }
      } else if (tok == 'restore') {
        Skip('restore');
        if (!EndOfStatement()) {
          curop += 'data_pos = data_labels["' + tok + '"];\n';
          Next();
        } else {
          curop += 'data_pos = 0;\n';
        }
      } else if (tok == 'input') {
        Skip('input');
        if (tok[0] == '#') {
          // TODO: Implement.
          Next();
          if (tok == ';' || tok == ',') {
            Next();
          }
        }
        if (tok == ';') {
          Skip(';');
        }
        var prompt = '"? "';
        if (tok.substr(0, 1) == '"') {
          var prompt = tok;
          Next();
          if (tok == ';' || tok == ',') {
            Next();
          }
        }
        curop += 'Print([' + prompt + ', ";"]);\n';
        curop += 'PutCh(String.fromCharCode(219));\n';
        curop += 'LineClear();\n';
        NewOp();
        curop += 'ip += LineInput();\n';
        NewOp();
        var n = 0;
        while (!EndOfStatement()) {
          curop += GetVar() + ' = LineValue().split(",")[' + n++ + '];\n';
          if (tok != ',') {
            break;
          }
          Skip(',');
        }
      } else if (tok == 'print') {
        Skip('print');
        if (EndOfStatement()) {
          curop += 'Print([]);\n';
          return;
        }
        var fmt = null;
        if (tok == 'using') {
          Skip('using');
          fmt = Expression();
          Skip(';');
        }
        var items = [];
        var e = Expression();
        items.push(e);
        while (tok == ';' || tok == ',') {
          items.push('"' + tok + '"');
          Next();
          if (EndOfStatement()) {
            break;
          }
          var e = Expression();
          items.push(e);
        }
        if (fmt !== null) {
          curop += 'PrintUsing(' + fmt + ', [' + items.join(', ') + ']);\n';
        } else {
          curop += 'Print([' + items.join(', ') + ']);\n';
        }
      } else if (tok == 'select') {
        Skip('select');
        Skip('case');
        if (tok == 'as') {
          Skip('as');
          Skip('const');
        }
        var e = Expression();
        NewOp();
        flow.push(['select', e, ops.length - 1, [], [], null]);
      } else if (tok == 'case') {
        Skip('case');
        var f = flow.pop();
        if (f[0] != 'select') {
          Error('Case outside select');
        }
        NewOp();
        f[4].push(ops.length - 1);
        if (tok == 'else') {
          Skip('else');
          f[5] = ops.length;
          flow.push(f);
          return;
        }
        var e = Expression();
        if (tok == 'to') {
          Skip('to');
          var e1 = Expression();
          f[3].push([e, e1, ops.length]);
        } else {
          f[3].push([e, e, ops.length]);
          while (tok == ',') {
            Skip(',');
            var e = Expression();
            f[3].push([e, e, ops.length]);
          }
        }
        flow.push(f);
      } else if (tok == '') {
        return;
      } else if (tok == 'call' || (functions[tok] !== undefined &&
                                   functions[tok].is_subroutine)) {
        var name = tok;
        Next();
        if (name == 'call') {
          name = tok;
          Next();
          for (var method in bindings) {
            var parts = method.split('_');
            if (parts.length == 3 && parts[0] == 'call') {
              if (name == parts[1]) {
                Invoke(method, ParenArguments(parts[2]));
                return;
              }
            }
          }
          FunctionCall(name, {is_subroutine: true, is_call: true});
        } else {
          FunctionCall(name, {is_subroutine: true});
        }
      } else {
        var name = tok;
        Next();
        for (var method in bindings) {
          var parts = method.split('_');
          if (parts.length == 3 && parts[0] == 'statement') {
            if (name == parts[1]) {
              Invoke(method, Arguments(parts[2]));
              return;
            }
          }
        }
        if (tok == ':') {
          Skip(':');
          AddLabel(name);
          Statement();
          return;
        }
        if (name == 'let') {
          name = tok;
          Next();
        }
        var vname = IndexVariable(name, true);
        if (tok == '=' || tok == '+=' || tok == '-=' ||
            tok == '*=' || tok == '/=' || tok == '\\=' ||
            tok == '^=' || tok == '&=') {
          var op = tok;
          Next();
          var e = Expression();
          if (op == '&=') {
            op = '+=';
          } else if (op == '\\=') {
            op = '//=';
          } else if (op == '^=') {
            curop += vname + ' = Math.pow(' + vname + ', ' + e + ');\n';
            return;
          }
          curop += vname + ' ' + op + ' (' + e + ');\n';
        } else {
          Error('Expected "=" or "x=" found "' + tok + '"');
        }
      }
    }

    function Compile() {
      NewOp();
      while (tok != '') {
        for (;;) {
          // Implement line numbers.
          if (tok.match(/^[0-9]+$/)) {
            AddLabel(tok);
            Next();
          }
          Statement();
          while (tok == ':') {
            Next();
            Statement();
          }
          if (tok == '') {
            break;
          }
          SkipEndOfStatement();
        }
      }

      // Check for matching flow control.
      if (flow.length != 0) {
        var f = flow.pop();
        Error('Unmatched ' + f[0]);
      }

      // Implicit End.
      NewOp();
      curop += 'End();';
      NewOp();

      // Align to 8.
      Align(8);

      // Allocate stack.
      stack = Allocate(STACK_SIZE);
      sp = stack;
      bp = sp;

      var total = '';
      total += '(function(bindings) {\n';
      for (var i in bindings) {
        total += 'var ' + i + ' = bindings["' + i + '"];\n';
      }
      total += 'var buffer = new ArrayBuffer(' +
          allocated + ' + ' + DYNAMIC_HEAP_SIZE + ');\n';
      for (var i in SIMPLE_TYPE_INFO) {
        var info = SIMPLE_TYPE_INFO[i];
        if (i == 'string') {
          total += 'var str = [];\n';
        } else {
          total += 'var ' + info.view +
            ' = new ' + info.array + '(buffer);\n';
        }
      }
      total += var_decls;
      total += 'for (var j = 0; j < ops.length; ++j) {\n';
      if (debugging_mode) {
        total += '  console.info("L" + j + ":\\n" + ops[j]);\n';
      }
      total += '  ops[j] = eval("(function() {\\n" + ops[j] + "})\\n");\n';
      total += '}\n';
      total += '})';
      if (debugging_mode) {
        console.info(total);
      }
      eval(total)(bindings);
    }

    function MidReplace(a, n, m, v) {
      var k = Math.min(m, v.length);
      return a.substr(0, n - 1) + v.substr(0, k) + a.substr(n - 1 + k);
    }

    function Right(s, n) {
      return s.substr(s.length - n);
    }

    function Read() {
      if (data_pos >= data.length) {
        Error('Out of data');
      }
      return data[data_pos++];
    }

    function Print(items) {
      if (items.length == 0) {
        bindings.PutCh();
        return;
      }
      for (var i = 0; i < items.length; i += 2) {
        var text;
        if (items[i] === undefined) {
          text = '';
        } else {
          text = items[i].toString();
        }
        for (var j = 0; j < text.length; j++) {
          bindings.PutCh(text[j]);
        }
        if (items[i + 1] == ',') {
          bindings.PutCh(' ');
          bindings.PutCh(' ');
          bindings.PutCh(' ');
        }
        if (items[i + 1] != ';' && items[i + 1] != ',') {
          bindings.PutCh();
        }
      }
    }

    function Using(format, value) {
      var sgn = value < 0 ? -1 : (value > 0 ? 1 : 0);
      value = Math.abs(value);
      var before = 0;
      var after = 0;
      var found_point = false;
      for (var i = 0; i < format.length; ++i) {
        if (format[i] == '.') {
          found_point = true;
        } else if (format[i] == '#') {
          if (found_point) {
            ++after;
          } else {
            ++before;
          }
        }
      }
      var t = value;
      var fail = Math.floor(t * Math.pow(10, -before)) > 0;
      value = value * Math.pow(10, after);
      var ret = '';
      var done = false;
      for (var i = format.length - 1; i >= 0; --i) {
        if (format[i] == '#') {
          if (fail) {
            ret = '*' + ret;
          } else if (done) {
            ret = ' ' + ret;
          } else {
            ret = Math.floor(value % 10) + ret;
            value = Math.floor(value / 10);
            if (value == 0) {
              done = true;
            }
          }
        } else if (format[i] == '+' || format[i] == '-') {
          if (fail) {
            ret = '*' + ret;
          } else if (sgn < 0) {
            ret = '-' + ret;
          } else if (sgn > 0) {
            if (format[i] == '+') {
              ret = '+' + ret;
            }
          } else {
            ret = ' ' + ret;
          }
        } else if (format[i] == ',') {
          if (fail) {
            ret = '*' + ret;
          } else if (done) {
            ret = ' ' + ret;
          } else {
            ret = ',' + ret;
          }
        } else {
          ret = format[i] + ret;
        }
      }
      return ret;
    }

    function PrintUsing(format, items) {
      var parts = [];
      var p = '';
      var has_num = false;
      for (var i = 0; i < format.length; ++i) {
        if (format[i] == '#' || format[i] == ',' || format[i] == '.') {
          has_num = true;
        } else {
          if (has_num) {
            parts.push(p)
            p = '';
            has_num = false;
          }
        }
        p += format[i];
      }
      if (p != '') {
        if (has_num) {
          parts.push(p);
        } else {
          parts[parts.length - 1] += p;
        }
      }
      var values = [];
      for (var i = 0; i < items.length; i += 2) {
        if (parts.length * 2 > i) {
          items[i] = Using(parts[(i / 2) | 0], items[i]);
        }
      }
      Print(items);
    }

    function Sleep(t) {
      yielding = 1;
      delay = t;
    }

    function Yield() {
      yielding = 1;
    }

    function End() {
      yielding = 1;
      quitting = 1;
      bindings.Halt();
    }

    function Run(pace) {
      for (;;) {
        var last_time = new Date().getTime();
        var speed = pace !== undefined ? pace() : 100000;
        for (var i = 0; i < speed; ++i) {
          ops[ip++]();
          if (yielding) {
            yielding = 0;
            if (quitting) {
              return;
            }
            break;
          }
        }
        setTimeout(function() { Run(pace); }, delay + 16);
        delay = 0;
        break;
      }
    }

    bindings.Yield = Yield;
    var compiled_ok = false;
    try {
      Compile();
      compiled_ok = true;
    } catch (e) {
      if (bindings.Render) {
        bindings.statement_locate_iiI(1, 1);
        bindings.statement_color_iII(15);
        Print([e.toString(), ';']);
      } else {
        console.error(e.toString());
      }
      if (e.stack !== undefined) {
        console.info(e.stack);
      }
    }
    if (compiled_ok) {
      Run(bindings.Pace);
    }
  }

  function SetupCanvas(tag, full_window) {
    if (full_window) {
      document.body.style.width = '100%';
      document.body.style.height = '100%';
      document.body.style.margin = '0';
      document.body.style.border = '0';
      document.body.style.overflow = 'hidden';
      document.body.style.display = 'block';
    }
    var canvas = document.createElement('canvas');
    canvas.width = 800;
    canvas.height = 600;
    canvas.fromWWWBasic = true;
    if (full_window) {
      document.body.appendChild(canvas);
    } else {
      tag.insertAdjacentElement('beforebegin', canvas);
    }
    var context = canvas.getContext('2d');
    context.fillStyle = 'black';
    context.fillRect(0, 0, canvas.width, canvas.height);
    context.fillStyle = 'white';
    context.strokeStyle = 'white';
    return canvas;
  }

  var timer_halted = 0;
  var timer_offset = 0;

  function GetTimer() {
    var t = new Date().getTime() / 1000;
    return t + timer_offset;
  }

  function Init() {
    var tags = document.getElementsByTagName('script');
    var count = 0;
    for (var t = 0; t < tags.length; ++t) {
      if (tags[t].type != 'text/basic') {
        continue;
      }
      ++count;
    }
    var full_window = count == 1 && document.body.innerText == '';
    for (var t = 0; t < tags.length; ++t) {
      if (tags[t].type != 'text/basic') {
        continue;
      }
      var tag = tags[t];
      var canvas = SetupCanvas(tag, full_window);
      var bindings = GraphicsBindings(canvas);
      if (tags[t].src) {
        var request = new XMLHttpRequest();
        request.addEventListener('load', function(e) {
          Basic(request.responseText, { bindings: bindings });
        }, false);
        request.open('GET', tag.src);
        request.send();
      } else {
        Basic(DecodeTag(tag.text), { bindings: bindings });
      }
    }
  }

  function Main() {
    if (typeof window !== 'undefined') {
      window.addEventListener('load', Init);
      window.addEventListener('focusout', function() {
        timer_halted = GetTimer();
      });
      window.addEventListener('focusin', function() {
        timer_offset = timer_halted - (new Date().getTime() / 1000);
      });
      window.Basic = function(code, canvas) {
        Basic(code, { bindings: GraphicsBindings(canvas) });
      };
    } else {
      for (var key in basic) {
        exports[key] = basic[key];
      }
    }
  }

  function ConsoleBindings() {
    var bindings = {};

    var output_buffer = '';

    // TODO: Cleanup, this should be hidden.
    bindings.PutCh = function(ch) {
      if (ch === undefined) {
        console.log(output_buffer);
        output_buffer = '';
      } else {
        output_buffer += ch;
      }
    }

    bindings.Halt = function() {
      if (output_buffer != '') {
        bindings.PutCh();
      }
    };

    return bindings;
  }

  function GraphicsBindings(canvas) {
    var bindings = {};

    const BLACK = 0xff000000;
    const WHITE = 0xffffffff;

    // Display Info (in browser only).
    var screen_mode = -1;
    var screen_bpp = 4;
    var text_mode = false;
    var text_width = 80;
    var text_height = 60;
    var font_height = 16;
    var screen_aspect = 1;
    var font_data;
    var ctx;
    var display;
    var display_data;
    var display_rgba;
    var display_text;
    var display_fg;
    var display_bg;
    var prepalette = new Uint32Array(256);
    var palette = new Uint32Array(256);
    var border_color = 0;
    var scale_canvas;

    function SetupDisplay(width, height, aspect, fheight) {
      if (!canvas) {
        return;
      }
      ctx = canvas.getContext('2d', { alpha: false });
      display = ctx.createImageData(width, height);
      display_rgba = new Uint32Array(display.data.buffer);
      display_data = new Uint32Array(display_rgba.length);
      if (!scale_canvas) {
        scale_canvas = document.createElement('canvas');
      }
      scale_canvas.width = width;
      scale_canvas.height = height;
      text_width = Math.floor(width / 8);
      text_height = Math.floor(height / fheight);
      display_text = new Uint8Array(text_width * text_height);
      display_fg = new Uint8Array(text_width * text_height);
      display_bg = new Uint8Array(text_width * text_height);
      border_color = 0;
      screen_aspect = aspect;
      font_height = fheight;
      var sctx = scale_canvas.getContext('2d', { alpha: false });
      font_data = CreateFont(sctx, font_height);
    }

    // Drawing and Console State
    var color_map;
    var fg_color = 7;
    var bg_color = 0;
    var default_fg_color = 7;
    var max_color = 15;
    var text_x = 0;
    var text_y = 0;
    var pen_x = 0;
    var pen_y = 0;

    // Input State
    var key_buffer = [];
    var ti_key_mode = 3;
    var input_string = '';
    var mouse_x = 0;
    var mouse_y = 0;
    var mouse_buttons = 0;
    var mouse_wheel = 0;
    var mouse_clip = 0;

    bindings.statement_getmouse_ooOOO = function() {
      bindings.Yield();
      return [mouse_x, mouse_y, mouse_wheel, mouse_buttons, mouse_clip];
    };

    bindings.Inkey = function() {
      bindings.Yield();
      if (key_buffer.length == 0) {
        return '';
      }
      var e = key_buffer.shift();
      return DecodeKey(e);
    };

    bindings.Point = function(x, y) {
      // TODO: Implement.
      return 0;
    };

    bindings.Peek = function(addr) {
      return 0;
    };

    function RGB(r, g, b) {
      return BLACK | r | (g << 8) | (b << 16);
    }

    const L = 0x55, M = 0xAA, H = 0xFF;
    const EGA16 = [
      RGB(0, 0, 0), RGB(0, 0, M), RGB(0, M, 0), RGB(0, M, M),
      RGB(M, 0, 0), RGB(M, 0, M), RGB(M, L, 0), RGB(M, M, M),
      RGB(L, L, L), RGB(L, L, H), RGB(L, H, L), RGB(L, H, H),
      RGB(H, L, L), RGB(H, L, H), RGB(H, H, L), RGB(H, H, H),
    ];
    const CGA1 = [
      [EGA16[0], EGA16[2], EGA16[4], EGA16[6]],
      [EGA16[0], EGA16[3], EGA16[5], EGA16[7]],
      [EGA16[0], EGA16[10], EGA16[12], EGA16[14]],
      [EGA16[0], EGA16[11], EGA16[13], EGA16[15]],
    ];
    const TI99 = [
      0, RGB(0x00, 0x00, 0x00),
      RGB(0x21, 0xC8, 0x42), RGB(0x5E, 0xDC, 0x78),
      RGB(0x54, 0x55, 0xED), RGB(0x7D, 0x76, 0xFC),
      RGB(0xD4, 0x52, 0x4D), RGB(0x42, 0xEB, 0xF5),
      RGB(0xFC, 0x55, 0x54), RGB(0xFF, 0x79, 0x78),
      RGB(0xD4, 0xC1, 0x54), RGB(0xE6, 0xCE, 0x80),
      RGB(0x21, 0xB0, 0x3B), RGB(0xC9, 0x5B, 0xBA),
      RGB(0xCC, 0xCC, 0xCC), RGB(0xFF, 0xFF, 0xFF),
    ];

    bindings.statement_screen_iIII = function(mode, cswitch, active, visual) {
      // TODO: Factor mode setup better.
      // TODO: Support pages.
      if (!canvas) {
        return;
      }
      if (mode == screen_mode) {
        return;
      }
      var monochrome = [BLACK, WHITE];
      var modes = {
        0: [640, 200, 2.4, 8, EGA16, 4],
        1: [320, 200, 1.2, 8, CGA1[1], 2],
        2: [640, 200, 2.4, 8, monochrome, 1],
        7: [320, 200, 1.2, 8, EGA16, 4],
        8: [640, 200, 2.4, 8, EGA16, 4],
        9: [640, 350, 480 / 350, 14, EGA16, 4],
        11: [640, 480, 1, 16, monochrome, 2],
        12: [640, 480, 1, 16, EGA16, 4],
        13: [320, 200, 1.2, 8, undefined, 24],
        14: [320, 240, 1, 16, undefined, 24],
        15: [400, 300, 1, 16, undefined, 24],
        16: [512, 384, 1, 16, undefined, 24],
        17: [640, 400, 1.2, 16, undefined, 24],
        18: [640, 480, 1, 16, undefined, 24],
        19: [800, 600, 1, 16, undefined, 24],
        20: [1024, 768, 1, 16, undefined, 24],
        21: [1280, 1024, 1, 16, undefined, 24],
        100: [256, 192, 1, 8, TI99, 6]
      };
      var m = modes[mode];
      if (m === undefined) {
        Error('Invalid mode ' + mode);
      }
      text_mode = mode == 0 || mode == 100;
      SetupDisplay(m[0], m[1], m[2], m[3]);
      color_map = m[4];
      screen_bpp = m[5];
      if (color_map === undefined || color_map.length == 16) {
        default_fg_color = 7;
      } else {
        default_fg_color = color_map.length - 1;
      }
      max_color = (1 << screen_bpp) - 1;
      fg_color = default_fg_color;
      bg_color = 0;
      if (color_map !== undefined) {
        for (var i = 0; i < 256; ++i) {
          prepalette[i] = i;
          palette[i] = color_map[i] | 0;
        }
      }
      screen_mode = mode;
      text_x = 0;
      text_y = mode == 100 ? text_height - 1 : 0;
      pen_x = display.width / 2;
      pen_y = display.height / 2;
      // TI default palette setup.
      if (mode == 100) {
        // TODO: Factor out by platform.
        bindings.call_screen_i(4);
        for (var i = 0; i < 32; i++) {
          bindings.call_color_iii(i, 2, 1);
        }
        bindings.call_clear_();
      } else {
        bindings.statement_cls_I(0);
      }
    }

    bindings.statement_width_iI = function(w, h) {
      // TODO: support height?
      if (screen_mode == 0 && (w == 80 || w == 40)) {
        SetupDisplay(w * 8, display.height, w == 80 ? 2.4 : 1.2, font_height);
      }
    };

    bindings.Halt = function() {
      console.log('=== BASIC END ===');
    };

    // TODO: Cleanup, this should be hidden.
    bindings.DrawChar = function(col, row, ch, fg, bg) {
      var ch = (ch & 0xff) >>> 0;
      var chpos = ch * font_height * 8;
      for (var y = 0; y < font_height; ++y) {
        var pos = col * 8 + (y + row * font_height) * display.width;
        for (var x = 0; x < 8; ++x) {
          display_data[pos++] = font_data[chpos++] ? fg : bg;
        }
      }
    };

    function SetChar(x, y, ch, fg, bg) {
      var pos = x + y * text_width;
      display_text[pos] = ch;
      display_fg[pos] = fg;
      display_bg[pos] = bg;
    }

    function SetTiChar(x, y, ch) {
      var bank = (ch >> 3) << 1;
      SetChar(x, y, ch, bank, bank + 1);
    }

    // TODO: Separate.
    bindings.call_screen_i = function(col) {
      palette[0] = TI99[col - 1];
      border_color = palette[0];
    };

    // TODO: Separate.
    bindings.call_clear_ = function() {
      if (screen_mode != 100) {
        bindings.statement_screen_iIII(100);
      }
      for (var j = 0; j < text_height; ++j) {
        for (var i = 0; i < text_width; ++i) {
          SetTiChar(i, j, 32);
        }
      }
    };

    // TODO: Separate.
    bindings.call_char_ii = function(ch, pattern) {
      pattern = (pattern + '0000000000000000').substr(0, 16);
      var chpos = ch * font_height * 8;
      for (var i = 0; i < 16; i++) {
        var code = parseInt(pattern.substr(i, 1), 16);
        for (var j = 0; j < 4; j++) {
          font_data[chpos++] = code & (0x8 >> j) ? 255 : 0;
        }
      }
    };

    function DecodeTiKeyPos(e) {
      const base_map = [
        '1234567890=',
        'qwertyuiop/',
        'asdfghjkl;\n',
        'zxcvbnm,.',
      ];
      for (var j = 0; j < base_map.length; j++) {
        for (var i = 0; i < base_map[j].length; ++i) {
          if (e.key == base_map[j][i]) {
            return [i, j, i < 5 ? 1 : 2];
          }
        }
      }
      return [-1, -1, -1];
    }

    function DecodeTiCtrl(ch) {
      if (ch.length != 1) {
        return -1;
      } else if (ch == '.') {
        return 27;
      } else if (ch == ';') {
        return 28;
      } else if (ch == '=') {
        return 29;
      } else if (ch == '8') {
        return 30;
      } else if (ch == '9') {
        return 31;
      }
      var k = ch.toUpperCase().charCodeAt(0);
      if (k >= 65 && k <= 90) {
        return k - 64;
      }
      return -1;
    }

    function DecodeTiFunction(e) {
      const map3 = [
        [3, 4, 7, 2, 14, 12, 1, 6, 15, -1, 5],
        [-1, -1, 11, -1, -1, -1, -1, -1, -1, -1, -1],
        [-1, 8, 9, -1, -1, -1, -1, -1, -1, -1, 13],
        [-1, 10, -1, -1, -1, -1, -1, -1, -1],
      ];
      // [col, row, side]
      var pos = DecodeTiKeyPos(e);
      if (pos[0] == -1) {
        return -1;
      }
      return map3[pos[1]][pos[0]];
    }

    function DecodeTiSide(e, side) {
      const map12 = [
        [19, 7, 8, 9, 10, 19, 7, 8, 9, 10, -1],
        [18, 4, 5, 6, 11, 18, 4, 5, 6, 11, 16],
        [1, 2, 3, 12, 17, 1, 2, 3, 12, 17, -1],
        [15, 0, 14, 13, 16, 15, 0, 14, 13],
      ];
      // [col, row, side]
      var pos = DecodeTiKeyPos(e);
      if (pos[0] == -1 || pos[2] != side) {
        return -1;
      }
      return map12[pos[1]][pos[0]];
    }

    // TODO: Separate.
    bindings.call_key_ioo = function(key_unit) {
      // TODO: Hold state better + allow sides to be independent.
      ti_key_mode = key_unit != 0 ? key_unit : ti_key_mode;
      bindings.Yield();
      if (key_buffer.length == 0) {
        return [-1, 0];
      }
      var e = key_buffer.shift();
      var state = e.repeat ? -1 : 1;

      if (ti_key_mode == 1 || ti_key_mode == 2) {
        var k = DecodeTiSide(e, ti_key_mode);
        if (k >= 0) {
          return [k, state];
        }
      } else if (ti_key_mode >= 3 && ti_key_mode <= 5) {
        if (e.key == 'Enter') {
          return [13, state];
        }
        if (e.altKey) {
          var k = DecodeTiFunction(e);
          if (k >= 0) {
            return [k + (ti_key_mode == 4 ? 128 : 0), state];
          }
        } else if (e.ctrlKey && ti_key_mode >= 4) {
          if (e.key == '/' && ti_key_mode == 5) {
            return [187, state];
          }
          var k = DecodeTiCtrl(e.key);
          if (k >= 0) {
            return [k + (ti_key_mode == 5 ? 128 : 0), state];
          }
        } else if (!e.altKey && !e.ctrlKey && e.key.length == 1) {
          var ch = ti_key_mode == 3 ? e.key.toUpperCase() : e.key;
          return [ch.charCodeAt(0), state];
        }
      }
      return [-1, 0];
    };

    // TODO: Separate.
    bindings.call_sound_iiiIIIIII = function(
      duration, f1, v1, f2, v2, f3, v3, f4, v4) {
      // TODO: Implement.
    };

    // TODO: Separate.
    bindings.call_color_iii = function(bank, fg, bg) {
      // Bank 1 is 32.
      bank += 3;
      prepalette[bank * 2 + 0] = fg - 1;
      prepalette[bank * 2 + 1] = bg - 1;
    };

    // TODO: Separate.
    bindings.call_hchar_iiiI = function(row, col, ch, n) {
      n = n === undefined ? 1 : n;
      row -= 1;
      col -= 1;
      if (n < 0) { Error('Bad value'); }
      for (var i = 0; i < n; i++) {
        SetTiChar(col, row, ch);
        ++col;
        if (col >= 32) {
          col = 0;
          ++row;
          if (row >= 24) {
            row = 0;
          }
        }
      }
    };

    // TODO: Separate.
    bindings.call_vchar_iiiI = function(row, col, ch, n) {
      n = n === undefined ? 1 : n;
      row -= 1;
      col -= 1;
      if (n < 0) { Error('Bad value'); }
      for (var i = 0; i < n; i++) {
        SetTiChar(col, row, ch);
        ++row;
        if (row >= 24) {
          row = 0;
          ++col;
          if (col >= 24) {
            col = 0;
          }
        }
      }
    };

    // TODO: Separate.
    bindings.call_gchar_iio = function(row, col) {
      row -= 1;
      col -= 1;
      return [display_text[col + row * text_width]];
    };

    function ScrollUp() {
      for (var j = 0; j < text_height - 1; ++j) {
        if (text_mode) {
          var pos = j * text_width;
          for (var i = 0; i < text_width; ++i) {
            display_text[i + pos] = display_text[i + pos + text_width];
            display_fg[i + pos] = display_fg[i + pos + text_width];
            display_bg[i + pos] = display_bg[i + pos + text_width];
          }
        } else {
          var pos = j * text_width * text_height;
          var offset = text_width * font_height * 8;
          for (var k = 0; k < font_height; ++k) {
            for (var i = 0; i < text_width; ++i) {
              display_data[i + pos] = display_data[i + pos + offset];
            }
          }
        }
      }
      if (text_mode) {
        var pos = (text_height - 1) * text_width;
        for (var i = 0; i < text_width; ++i) {
          display_text[i + pos] = 32;
          display_fg[i + pos] = fg_color;
          display_bg[i + pos] = bg_color;
        }
      } else {
        for (var i = 0; i < text_width; ++i) {
          bindings.DrawChar(i, text_height - 1, 32, fg_color, bg_color);
        }
      }
    }

    // TODO: Cleanup, this should be hidden.
    bindings.PutCh = function(ch) {
      if (ch === undefined) {
        if (text_mode) {
          var n = text_width - text_x;
          for (var i = 0; i < n; ++i) {
            bindings.PutCh(' ');
          }
          return;
        }
        text_x = 0;
        text_y++;
        return;
      }
      var code = ch.charCodeAt(0);
      if (screen_mode == 0) {
        // PC - text
        SetChar(text_x, text_y, code, fg_color, bg_color);
      } else if (screen_mode == 100) {
        // TI
        SetTiChar(text_x, text_y, code);
      } else {
        // PC - graphics
        bindings.DrawChar(text_x, text_y, code, fg_color, bg_color);
      }
      text_x++;
      if (text_x >= text_width) {
        text_y++;
        text_x = 0;
      }
      if (text_y >= text_height) {
        ScrollUp();
        --text_y;
      }
    };

    bindings.LineClear = function() {
      input_string = '';
    };

    bindings.LineValue = function() {
      return input_string;
    };

    bindings.LineInput = function() {
      while (key_buffer.length > 0) {
        const key = DecodeKey(key_buffer.shift());
        if (key == String.fromCharCode(13)) {
          --text_x;
          bindings.PutCh(' ');
          bindings.PutCh();
          return 0;
        }
        if (key == String.fromCharCode(8) && input_string.length > 0) {
          input_string = input_string.substr(0, input_string.length - 1);
          --text_x;
          bindings.PutCh(' ');
          text_x -= 2;
          bindings.PutCh(String.fromCharCode(219));
        }
        if (key.charCodeAt(0) >= 32 && key.charCodeAt(0) <= 126) {
          --text_x;
          bindings.PutCh(key);
          bindings.PutCh(String.fromCharCode(219));
          input_string += key;
        }
      }
      bindings.Yield();
      return -1;
    };

    function ColorFlip(c) {
      return BLACK |
        ((c & 0xff0000) >> 16) | ((c & 0xff) << 16) | (c & 0x00ff00);
    }

    bindings.statement_palette_ii = function(c, p) {
      var r = 85 * (((p >> 1) & 2) | (p >> 5) & 1);
      var g = 85 * ((p & 2) | (p >> 4) & 1);
      var b = 85 * (((p << 1) & 2) | (p >> 3) & 1);
      palette[c] = RGB(r, g, b);
    };

    bindings.statement_color_iII = function(fg, bg, border) {
      if (screen_mode == 0) {
        border_color = EGA16[border];
      }
      if (screen_mode == 2) {
        Error('Illegal function call');
        return;
      }
      if (screen_mode == 1) {
        if (fg !== undefined) {
          palette[0] = EGA16[fg & 15];
          border_color = palette[0];
        }
        if (bg !== undefined) {
          for (var i = 1; i < 4; ++i) {
            palette[i] = CGA1[bg & 3][i];
          }
        }
        return;
      }
      fg_color = fg === undefined ? default_fg_color : fg;
      if (screen_mode > 0) {
        bg_color = 0;
      } else {
        bg_color = bg === undefined ? 0 : bg;
      }
    };

    bindings.statement_locate_iiI = function(y, x, cursor) {
      // TODO: Support cursor?
      text_x = x - 1;
      text_y = y - 1;
      // Hack to yield more often (for NIBBLES.BAS)
      if (x == 1 && y == 1) {
        bindings.Yield();
      }
    };

    function Box(x1, y1, x2, y2, c) {
      x1 = x1 | 0;
      y1 = y1 | 0;
      x2 = x2 | 0;
      y2 = y2 | 0;
      c = c | 0;
      if (x1 > x2) {
        var t = x2;
        x2 = x1;
        x1 = t;
      }
      if (y1 > y2) {
        var t = y2;
        y2 = y1;
        y1 = t;
      }
      if (x1 >= display.width ||
          y1 >= display.height ||
          x2 < 0 || y2 < 0) {
        return;
      }
      if (x1 < 0) x1 = 0;
      if (x2 > display.width - 1) x2 = display.width - 1;
      if (y1 < 0) y1 = 0;
      if (y2 > display.height - 1) y2 = display.height - 1;
      for (var y = y1; y <= y2; ++y) {
        var pos = x1 + y * display.width;
        for (var x = x1; x <= x2; ++x) {
          display_data[pos++] = c;
        }
      }
    }

    function RawLine(x1, y1, x2, y2, c) {
      x1 = x1 | 0;
      y1 = y1 | 0;
      x2 = x2 | 0;
      y2 = y2 | 0;
      if (x1 == x2 || y1 == y2) {
        Box(x1, y1, x2, y2, c);
        return;
      }
      if (Math.abs(x1 - x2) > Math.abs(y1 - y2)) {
        if (x1 > x2) {
          var tmp;
          tmp = x1; x1 = x2; x2 = tmp;
          tmp = y1; y1 = y2; y2 = tmp;
        }
        for (var x = x1; x <= x2; ++x) {
          var t = (x - x1) / (x2 - x1);
          var y = y1 + Math.floor(t * (y2 - y1));
          Box(x, y, x, y, c);
        }
      } else {
        if (y1 > y2) {
          var tmp;
          tmp = x1; x1 = x2; x2 = tmp;
          tmp = y1; y1 = y2; y2 = tmp;
        }
        for (var y = y1; y <= y2; ++y) {
          var t = (y - y1) / (y2 - y1);
          var x = x1 + Math.floor(t * (x2 - x1));
          Box(x, y, x, y, c);
        }
      }
    }

    // Not bound direct otherwise would be statement_line_PdpIS.
    bindings.Line = function(x1, y1, x2, y2, c, fill) {
      c = c === undefined ? default_fg_color : (c & max_color);
      if (x1 === undefined) {
        x1 = pen_x;
        y1 = pen_y;
      }
      if (fill == 'bf') {
        Box(x1, y1, x2, y2, c);
      } else if (fill == 'b') {
        Box(x1, y1, x2, y1, c);
        Box(x1, y2, x2, y2, c);
        Box(x1, y1, x1, y2, c);
        Box(x2, y1, x2, y2, c);
      } else {
        RawLine(x1, y1, x2, y2, c);
      }
    };

    bindings.statement_cls_I = function(mode) {
      if (screen_mode == 100) {
        for (var j = 0; j < text_height; ++j) {
          for (var i = 0; i < text_width; ++i) {
            SetTiChar(i, j, 32);
          }
        }
      } else if (text_mode) {
        for (var j = 0; j < text_height; ++j) {
          for (var i = 0; i < text_width; ++i) {
            SetChar(i, j, 32, fg_color, bg_color);
          }
        }
      } else {
        Box(0, 0, display.width, display.height, bg_color);
      }
      text_x = 0;
      text_y = 0;
    };

    bindings.statement_pset_pI = function(x, y, c) {
      c = c === undefined ? default_fg_color : (c & max_color);
      display_data[x + y * display.width] = c;
      pen_x = x;
      pen_y = y;
    }

    bindings.statement_preset_pI = function(x, y, c) {
      c = c === undefined ? 0 : (c & max_color);
      display_data[x + y * display.width] = c;
      pen_x = x;
      pen_y = y;
    }

    bindings.statement_sound_ii = function(freq, duration) {
      // TODO: implement.
    };

    bindings.statement_play_i = function(cmds) {
      // TODO: implement.
    };

    function Paint(x, y, r, c, start, end, aspect, fill) {
      c = c === undefined ? default_fg_color : (c & max_color);
      start = start === undefined ? 0 : start;
      end = end == undefined ? Math.PI * 2 : end;
      x += 0.5;
      y += 0.5;
      var complete = false;
      if (start < 0) { start = -start; complete = true; }
      if (end < 0) { end = -end; complete = true; }
      if (end < start) {
        end += Math.PI * 2;
      }
      var rx, ry;
      if (aspect == null) {
        rx = r;
        ry = r / screen_aspect;
      } else if (aspect > 1) {
        rx = r / aspect;
        ry = r;
      } else {
        rx = r;
        ry = r * aspect;
      }
      var oxx = x + Math.cos(start) * rx;
      var oyy = y - Math.sin(start) * ry;
      if (complete) {
        RawLine(x, y, oxx, oyy, c);
      }
      for (var ang = start; ang <= end; ang += 0.03) {
        var xx = x + Math.cos(ang) * rx;
        var yy = y - Math.sin(ang) * ry;
        if (ang == start) { oxx = xx; oyy = yy; }
        RawLine(oxx, oyy, xx, yy, c);
        oxx = xx;
        oyy = yy;
      }
      if (complete) {
        RawLine(x, y, xx, yy, c);
      }
      if (fill && start == 0 && end == Math.PI * 2) {
        bindings.statement_paint_pII(x, y, c, c);
      }
    }
    bindings.statement_circle_piIIIIS = Paint;

    bindings.statement_get_pdpv = function(x1, y1, x2, y2, buffer, offset) {
      x1 = x1 | 0;
      y1 = y1 | 0;
      x2 = x2 | 0;
      y2 = y2 | 0;
      var d16 = new Uint16Array(buffer);
      if (screen_bpp <= 2) {
        d16[(offset >> 1) + 0] = (x2 - x1 + 1) * screen_bpp;
      } else {
        d16[(offset >> 1) + 0] = (x2 - x1 + 1);
      }
      d16[(offset >> 1) + 1] = y2 - y1 + 1;
      var d = new Uint8Array(buffer);
      var src = display_data;
      if (screen_bpp > 8) {
        var dstpos = offset + 4;
        for (var y = y1; y <= y2; ++y) {
          var srcpos = x1 + y * display.width;
          for (var x = x1; x <= x2; ++x) {
            var v = src[srcpos++];
            d[dstpos++] = v;
            d[dstpos++] = (v >> 8);
            d[dstpos++] = (v >> 16);
          }
        }
      } else {
        var dstpos = offset + 4;
        var shift = 8;
        var v = 0;
        for (var y = y1; y <= y2; ++y) {
          var srcpos = x1 + y * display.width;
          for (var x = x1; x <= x2; ++x) {
            shift -= screen_bpp;
            var cc = src[srcpos++];
            v |= (cc << shift);
            if (shift == 0) {
              d[dstpos++] = v;
              v = 0;
              shift = 8;
            }
          }
          if (shift != 8) {
            d[dstpos++] = v;
            v = 0;
            shift = 8;
          }
        }
      }
    };

    bindings.statement_put_pvS = function(x1, y1, buffer, offset, mode) {
      x1 = x1 | 0;
      y1 = y1 | 0;
      mode = mode === undefined ? 'xor' : mode;
      var s16 = new Uint16Array(buffer);
      var x2;
      if (screen_bpp <= 2) {
        x2 = x1 + (s16[(offset >> 1) + 0] / screen_bpp) - 1;
      } else {
        x2 = x1 + s16[(offset >> 1)] - 1;
      }
      var y2 = y1 + s16[(offset >> 1) + 1] - 1;
      var s = new Uint8Array(buffer);
      var dst = display_data;
      if (screen_bpp > 8) {
        var srcpos = offset + 4;
        for (var y = y1; y <= y2; ++y) {
          var dstpos = x1 + y * display.width;
          for (var x = x1; x <= x2; ++x) {
            var v = s[srcpos] | (s[srcpos + 1] << 8) | (s[srcpos + 2] << 16);
            srcpos += 3;
            // TODO: Optimize
            if (x < 0 || x >= display.width || y < 0 || y >= display.height) {
              dstpos++;
              continue;
            }
            if (mode == 'xor') {
              dst[dstpos++] = (dst[dstpos] ^ v) | BLACK;
            } else if (mode == 'preset') {
              dst[dstpos++] = (~v) | BLACK;
            } else if (mode == 'and') {
              dst[dstpos++] = (dst[dstpos] & v) | BLACK;
            } else if (mode == 'or') {
              dst[dstpos++] = (dst[dstpos] | v) | BLACK;
            } else {
              dst[dstpos++] = v | BLACK;
            }
          }
        }
      } else {
        var srcpos = offset + 4;
        var mask = (1 << screen_bpp) - 1;
        for (var y = y1; y <= y2; ++y) {
          var dstpos = x1 + y * display.width;
          var v = 0;
          var shift = 8;
          for (var x = x1; x <= x2; ++x) {
            if (shift == 8) {
              v = s[srcpos++];
            }
            shift -= screen_bpp;
            var cc = (v >> shift) & mask;
            var old = dst[dstpos] | 0;
            if (mode == 'xor') {
              cc ^= old;
            } else if (mode == 'preset') {
              cc = cc ^ mask;
            } else if (mode == 'and') {
              cc &= old;
            } else if (mode == 'or') {
              cc |= old;
            }
            // TODO: Optimize
            if (y >= 0 && y < display.height && x >= 0 && x < display.width) {
              dst[dstpos++] = cc;
            } else {
              dstpos++;
            }
            if (shift == 0) {
              shift = 8;
            }
          }
        }
      }
    };

    var draw_state = {
      noplot: false,
      nomove: false,
      angle: 0,
      turn_angle: 0,
      color: undefined,
      scale: 1,
    };

    function StepUnscaled(dx, dy) {
      if (!draw_state.noplot) {
        bindings.Line(
          pen_x, pen_y, pen_x + dx, pen_y + dy, draw_state.color, 0);
      }
      if (!draw_state.nomove) {
        pen_x += dx;
        pen_y += dy;
      }
      draw_state.noplot = false;
      draw_state.nomove = false;
    }

    function Step(dx, dy) {
      StepUnscaled(dx * draw_state.scale, dy * draw_state.scale);
    }

    bindings.statement_draw_i = function(cmds) {
      cmds = cmds.toLowerCase();
      var m;
      while (cmds.length) {
        if (m = cmds.match(/^(u|d|l|r|e|f|g|h|a|ta|c|s)([0-9]+)?/)) {
          var op = m[1];
          var n = m[2] == '' ? 1 : parseInt(m[2]);
          if (op == 'c') {
            draw_state.color = n & max_color;
          } else if (op == 'a') {
            draw_state.angle = n;
            // TODO: Implement.
          } else if (op == 'ta') {
            draw_state.turn_angle = n;
            // TODO: Implement.
          } else if (op == 's') {
            draw_state.scale = n / 4;
          } else if (op == 'u') {
            Step(0, -n);
          } else if (op == 'd') {
            Step(0, n);
          } else if (op == 'l') {
            Step(-n, 0);
          } else if (op == 'r') {
            Step(n, 0);
          } else if (op == 'e') {
            Step(n, -n);
          } else if (op == 'f') {
            Step(n, n);
          } else if (op == 'g') {
            Step(-n, n);
          } else if (op == 'h') {
            Step(-n, -n);
          }
        } else if (m = cmds.match(/^(m)([+-]?)([0-9]+)[,]([+-]?[0-9]+)/)) {
          var op = m[1];
          var sx = m[2];
          var x = parseInt(m[3]);
          var y = parseInt(m[4]);
          if (sx) {
            x = parseInt(sx + '1') * x;
            Step(x, y);
          } else {
            StepUnscaled(x - pen_x, y - pen_y);
          }
        } else if (m = cmds.match(/^(p)([0-9]+),([0-9]+1)/)) {
          var op = m[1];
          var x = parseInt(m[2]);
          var y = parseInt(m[3]);
          // TODO: Implement.
        } else if (m = cmds.match(/^(b|n)/)) {
          var op = m[1];
          if (op == 'b') {
            draw_state.noplot = true;
          } else if (op == 'n') {
            draw_state.nomove = true;
          }
        } else {
          Error('Bad drop op: ' + cmds);
        }
        cmds = cmds.substr(m[0].length);
      }
    };

    bindings.statement_paint_pII = function(x, y, paint, border) {
      if (paint === undefined) {
        paint = default_fg_color;
      }
      if (border === undefined) {
        border = paint;
      }
      paint = paint & max_color;
      border = border & max_color;
      var data = display_data;
      var pending = [];
      pending.push([Math.floor(x), Math.floor(y)]);
      while (pending.length) {
        var p = pending.pop();
        if (p[0] < 0 || p[0] >= display.width ||
            p[1] < 0 || p[1] >= display.height) {
          continue;
        }
        var pos = p[0] + p[1] * display.width;
        if ((data[pos] | 0) == border ||
            (data[pos] | 0) == paint) {
          continue;
        }
        data[pos] = paint;
        pending.push([p[0] - 1, p[1]]);
        pending.push([p[0] + 1, p[1]]);
        pending.push([p[0], p[1] - 1]);
        pending.push([p[0], p[1] + 1]);
      }
    };

    var viewport_x, viewport_y;
    var viewport_w, viewport_h;
    var border_x, border_y;
    var border_w, border_h;

    function Resize() {
      if (canvas.fromWWWBasic) {
        canvas.width = window.innerWidth;
        canvas.height = window.innerHeight;
      }
      var raspect = canvas.width / canvas.height;
      var aspect = display.width / (display.height * screen_aspect);
      const non_border = 0.9;
      if (raspect > aspect) {
        border_w = Math.floor(
          display.width * canvas.height / (display.height * screen_aspect));
        border_h = canvas.height;
      } else {
        border_w = canvas.width;
        border_h = Math.floor(
          (display.height * screen_aspect) * canvas.width / display.width);
      }
      border_x = Math.floor((canvas.width - border_w) / 2);
      border_y = Math.floor((canvas.height - border_h) / 2);
      viewport_w = Math.floor(border_w * non_border);
      viewport_h = Math.floor(border_h * non_border);
      viewport_x = Math.floor((canvas.width - viewport_w) / 2);
      viewport_y = Math.floor((canvas.height - viewport_h) / 2);
    }

    function RenderTextMode() {
      if (!text_mode) {
        return;
      }
      var pos = 0;
      for (var j = 0; j < text_height; ++j) {
        for (var i = 0; i < text_width; ++i) {
          var ch = display_text[pos];
          var fg = display_fg[pos];
          var bg = display_bg[pos];
          bindings.DrawChar(i, j, ch, fg, bg);
          ++pos;
        }
      }
    }

    function TranslatePalette() {
      var sz = display_rgba.length;
      if (screen_bpp < 24) {
        for (var i = 0; i < sz; ++i) {
          display_rgba[i] = palette[prepalette[display_data[i]]];
        }
      } else {
        for (var i = 0; i < sz; ++i) {
          display_rgba[i] = ColorFlip(display_data[i]);
        }
      }
    }

    function ToHex(c) {
      c = ColorFlip(c) & 0xffffff;
      var ret = c.toString(16);
      while (ret.length < 6) {
        ret = '0' + ret;
      }
      return '#' + ret;
    }

    function Render() {
      if (!canvas) {
        return;
      }
      var scale_ctx = scale_canvas.getContext('2d');
      RenderTextMode();
      TranslatePalette();
      scale_ctx.putImageData(display, 0, 0);
      var ctx = canvas.getContext('2d');
      ctx.fillStyle = '#111';
      ctx.fillRect(0, 0, canvas.width, canvas.height);
      ctx.fillStyle = ToHex(border_color);
      ctx.fillRect(border_x, border_y, border_w, border_h);
      //      ctx.imageSmoothingQuality = 'low';
      //      ctx.imageSmoothingEnabled = false;
      ctx.drawImage(scale_canvas, viewport_x, viewport_y,
        viewport_w, viewport_h);
      requestAnimationFrame(Render);
    }

    // Decode PC Keycode.
    function DecodeKey(e) {
      function RegularKey(n) {
        return String.fromCharCode(n);
      }

      function ExtendedKey(n) {
        return String.fromCharCode(0) + String.fromCharCode(n);
      }

      const SIMPLE_KEYMAP = {
        // BACKSPACE, ENTER, ESCAPE
        8: { regular: 8 }, 13: { regular: 13 }, 27: { regular: 27 },
        // INS, DEL
        45: { regular: 82 }, 46: { regular: 83 },
        // LEFT, RIGHT
        37: { extended: 75 }, 39: { extended: 77 },
        // UP, DOWN
        38: { extended: 72 }, 40: { extended: 80 },
        // PGUP, PGDN
        33: { extended: 73 }, 34: { extended: 81 },
        // HOME, END
        36: { extended: 71 }, 35: { extended: 79 },
      };
      if (e.keyCode >= 112 && e.keyCode <= 123) {
        // F1 - F10
        if (e.altKey) {
          return ExtendedKey(e.keyCode - 112 + 104);
        } else if (e.ctrlKey) {
          return ExtendedKey(e.keyCode - 112 + 94);
        } else if (e.shiftKey) {
          return ExtendedKey(e.keyCode - 112 + 84);
        } else {
          return ExtendedKey(e.keyCode - 112 + 59);
        }
      } else if (e.keyCode == 9) {
        // TAB, Shift-TAB
        if (e.shiftKey) {
          return RegularKey(15);
        } else {
          return RegularKey(9);
        }
      } else if (SIMPLE_KEYMAP[e.keyCode]) {
        if (SIMPLE_KEYMAP[e.keyCode].regular) {
          return RegularKey(SIMPLE_KEYMAP[e.keyCode].regular);
        } else {
          return ExtendedKey(SIMPLE_KEYMAP[e.keyCode].extended);
        }
      } else if (e.ctrlKey && e.keyCode >= 65 && e.keyCode <= 90) {
        // Ctrl-A to Ctrl-Z
        return RegularKey(e.keyCode - 65 + 1);
      } else if (e.altKey) {
        const ch = String.fromCharCode(e.keyCode);
        const row1 = '1234567890-='.indexOf(ch);
        const row2 = 'QWERTYUIOP'.indexOf(ch);
        const row3 = 'ASDFGHJKL'.indexOf(ch);
        const row4 = 'ZXCVBNM'.indexOf(ch);
        if (row1 >= 0) {
          return ExtendedKey(row1 + 120);
        } else if (row2 >= 0) {
          return ExtendedKey(row2 + 16);
        } else if (row3 >= 0) {
          return ExtendedKey(row3 + 30);
        } else if (row4 >= 0) {
          return ExtendedKey(row4 + 44);
        }
      } else {
        const code = e.key.charCodeAt(0);
        if (e.key.length == 1 && code >= 32 && code <= 126) {
          return RegularKey(code);
        }
      }
      return '';
    }

    function InitEvents() {
      if (!canvas) {
        return;
      }
      Resize();
      if (canvas.fromWWWBasic) {
        window.addEventListener('resize', Resize, false);
      }
      window.addEventListener('keydown', function(e) {
        key_buffer.push(e);
        if (canvas.fromWWWBasic && (!e.ctrlKey || !e.shiftKey)) {
          e.preventDefault();
        }
      }, false);
      canvas.addEventListener('mousemove', function(e) {
        // TODO: Generalize for non-fullscreen.
        //var rect = canvas.getBoundingClientRect();
        var rect = {left: 0, top: 0};
        mouse_x = Math.floor(
          (e.clientX - rect.left - viewport_x) * display.width / viewport_w);
        mouse_y = Math.floor(
          (e.clientY - rect.top - viewport_y) * display.height / viewport_h);
      }, false);
      canvas.addEventListener('touchmove', function(e) {
        var touch = e.touches.item(0);
        const evt = new Event('mousemove');
        evt.clientX = touch.clientX;
        evt.clientY = touch.clientY;
        canvas.dispatchEvent(evt);
      }, false);
      canvas.addEventListener('mousedown', function(e) {
        mouse_buttons = 1;
      }, false);
      canvas.addEventListener('touchstart', function(e) {
        canvas.dispatchEvent(new Event('mousedown'));
      }, false);
      canvas.addEventListener('mouseup', function(e) {
        mouse_buttons = 0;
      }, false);
      canvas.addEventListener('touchend', function(e) {
        canvas.dispatchEvent(new Event('mouseup'));
      }, false)
      // TODO: Implement Mouse Wheel!
      // TODO: Implement Mouse Clip!
    }

    bindings.Pace = function() {
      if ((screen_mode > 0 && screen_mode <= 2) || screen_mode == 100) {
        return 2;
      } else {
        return 100000;
      }
    };

    function CreateFont(ctx, height) {
      function RenderFont(ctx, height) {
        const CHARSET =
          '\u0020\u263a\u263b\u2665\u2666\u2663\u2660\u2022' +
          '\u25d8\u25cb\u25d9\u2642\u2640\u266a\u266b\u263c' +
          '\u25ba\u25c4\u2195\u203c\u00b6\u00a7\u25ac\u21a8' +
          '\u2191\u2193\u2192\u2190\u221f\u2194\u25b2\u25bc' +
          '\u0020\u0021\u0022\u0023\u0024\u0025\u0026\u0027' +
          '\u0028\u0029\u002a\u002b\u002c\u002d\u002e\u002f' +
          '\u0030\u0031\u0032\u0033\u0034\u0035\u0036\u0037' +
          '\u0038\u0039\u003a\u003b\u003c\u003d\u003e\u003f' +
          '\u0040\u0041\u0042\u0043\u0044\u0045\u0046\u0047' +
          '\u0048\u0049\u004a\u004b\u004c\u004d\u004e\u004f' +
          '\u0050\u0051\u0052\u0053\u0054\u0055\u0056\u0057' +
          '\u0058\u0059\u005a\u005b\u005c\u005d\u005e\u005f' +
          '\u0060\u0061\u0062\u0063\u0064\u0065\u0066\u0067' +
          '\u0068\u0069\u006a\u006b\u006c\u006d\u006e\u006f' +
          '\u0070\u0071\u0072\u0073\u0074\u0075\u0076\u0077' +
          '\u0078\u0079\u007a\u007b\u007c\u007d\u007e\u2302' +
          '\u00c7\u00fc\u00e9\u00e2\u00e4\u00e0\u00e5\u00e7' +
          '\u00ea\u00eb\u00e8\u00ef\u00ee\u00ec\u00c4\u00c5' +
          '\u00c9\u00e6\u00c6\u00f4\u00f6\u00f2\u00fb\u00f9' +
          '\u00ff\u00d6\u00dc\u00a2\u00a3\u00a5\u20a7\u0192' +
          '\u00e1\u00ed\u00f3\u00fa\u00f1\u00d1\u00aa\u00ba' +
          '\u00bf\u2310\u00ac\u00bd\u00bc\u00a1\u00ab\u00bb' +
          '\u2591\u2592\u2593\u2502\u2524\u2561\u2562\u2556' +
          '\u2555\u2563\u2551\u2557\u255d\u255c\u255b\u2510' +
          '\u2514\u2534\u252c\u251c\u2500\u253c\u255e\u255f' +
          '\u255a\u2554\u2569\u2566\u2560\u2550\u256c\u2567' +
          '\u2568\u2564\u2565\u2559\u2558\u2552\u2553\u256b' +
          '\u256a\u2518\u250c\u2588\u0020\u258c\u2590\u2580' +
          '\u03b1\u00df\u0393\u03c0\u03a3\u03c3\u00b5\u03c4' +
          '\u03a6\u0398\u03a9\u03b4\u221e\u03c6\u03b5\u2229' +
          '\u2261\u00b1\u2265\u2264\u2320\u2321\u00f7\u2248' +
          '\u00b0\u2219\u00b7\u221a\u207f\u00b2\u25a0\u0020';
        var data = new Uint8Array(256 * 8 * height);
        var pos = 0;
        for (var i = 0; i < 256; ++i) {
          ctx.fillStyle = '#000';
          ctx.fillRect(0, 0, 16, 32);
          ctx.textBaseline = 'top';
          ctx.font = 'bold 16px monospace';
          ctx.save();
          ctx.scale(1, height / 16);
          ctx.fillStyle = '#fff';
          ctx.fillText(CHARSET.charAt(i), 0, 0);
          ctx.restore();
          var pix = ctx.getImageData(0, 0, 8, height);
          var pdata = pix.data;
          for (var j = 0; j < pdata.length; j += 4) {
            var level = pdata[j] * 0.1140 +
              pdata[j + 1] * 0.5870 +
              pdata[j + 2] * 0.2989;
            data[pos++] = level > 128 ? 255 : 0;
          }
        }
        return data;
      }

      function LoadFont(s, dup) {
        var data = new Uint8Array(s.length * dup);
        var pos = 0;
        for (var i = 0; i < 256; ++i) {
          var row = Math.floor(i / 8);
          var col = i % 8;
          for (var y = 0; y < 8; ++y) {
            for (var d = 0; d < dup; ++d) {
              for (var x = 0; x < 8; ++x) {
                data[pos++] = s[x + y * 8 * 8 + col * 8 + row * 64 * 8]
                  != ' ' ? 255 : 0;
              }
            }
          }
        }
        return data;
      }

      var FONT8 =
        'x     x   XXX     XXX   xx   xx x     x                         ' +
        '         X   X   XXXXX                                          ' +
        '        X X X X XX X XX            x                            ' +
        '        X     X XXXXXXX                                         ' +
        '        X XXX X XX   XX                                         ' +
        '         X   X   XXXXX                                          ' +
        'x     x   XXX     XXX   xx   xx x     x                         ' +
        '                                                                ' +

        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '                                                                ' +

        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '                                                                ' +

        '   X       X                    XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '  XXX      X        X     X     XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        ' XXXXX     X        XX   XX     XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '   X       X    XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '   X     XXXXX      XX   XX     XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '   X      XXX       X     X     XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '   X       X                    XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '                                                                ' +

        '           XX    XX XX   XX XX   XX XX  XX       XXX       XX   ' +
        '           XX    XX XX   XX XX  XXXXXXX XX  XX  XX XX      XX   ' +
        '           XX           XXXXXXX XX         XX    XXX            ' +
        '           XX            XX XX   XXXXX    XX    XXXX XX         ' +
        '           XX           XXXXXXX      XX  XX     XX XXX          ' +
        '                         XX XX  XXXXXXX XX  XX  XX XXX          ' +
        '           XX            XX XX   XX XX      XX   XXX XX         ' +
        '                                                                ' +

        '   XX     XX                                                    ' +
        '  XX       XX   XX X XX   XX                                 XX ' +
        ' XX         XX    XXX     XX                                XX  ' +
        ' XX         XX  XXXXXXX XXXXXX           XXXXX             XX   ' +
        ' XX         XX    XXX     XX                              XX    ' +
        '  XX       XX   XX X XX   XX       XX                    XX     ' +
        '   XX     XX                       XX              XX   XX      ' +
        '                                  XX               XX           ' +

        ' XXXXX     XX    XXXXX   XXXXX  XX  XX  XXXXXXX  XXXXX  XXXXXXX ' +
        'XX  XXX   XXX   XX   XX XX   XX XX  XX  XX      XX   XX      XX ' +
        'XX XXXX  XXXX        XX      XX XX  XX  XX      XX          XX  ' +
        'XXXX XX    XX      XXX    XXXX  XXXXXXX  XXXXX  XXXXXX     XX   ' +
        'XX   XX    XX    XXX         XX     XX       XX XX   XX   XX    ' +
        'XX   XX    XX   XX      XX   XX     XX  XX   XX XX   XX   XX    ' +
        ' XXXXX  XXXXXXX XXXXXXX  XXXXX      XX   XXXXX   XXXXX    XX    ' +
        '                                                                ' +

        ' XXXXX   XXXXX                                           XXXXX  ' +
        'XX   XX XX   XX    XX      XX       XXX         XXX     XX   XX ' +
        'XX   XX XX   XX    XX      XX     XXX   XXXXXXX   XXX   XX   XX ' +
        ' XXXXX   XXXXXX                 XXX                 XXX     XX  ' +
        'XX   XX      XX    XX      XX     XXX   XXXXXXX   XXX      XX   ' +
        'XX   XX XX   XX    XX      XX       XXX         XXX             ' +
        ' XXXXX   XXXXX            XX                               XX   ' +
        '                                                                ' +

        ' XXXXX    XXX   XXXXXX   XXXXXX XXXXXX  XXXXXXX XXXXXXX  XXXXX  ' +
        'XX  XXX  XX XX  XX   XX XX      XX   XX XX      XX      XX   XX ' +
        'XX XXXX XX   XX XX   XX XX      XX   XX XX      XX      XX      ' +
        'XX XXXX XXXXXXX XXXXXX  XX      XX   XX XXXXX   XXXXX   XX XXXX ' +
        'XX  XXX XX   XX XX   XX XX      XX   XX XX      XX      XX   XX ' +
        'XX      XX   XX XX   XX XX      XX   XX XX      XX      XX   XX ' +
        ' XXXXX  XX   XX XXXXXX   XXXXXX XXXXXX  XXXXXXX XX       XXXXX  ' +
        '                                                                ' +

        'XX   XX XXXXXXX      XX XX   XX XX      XX   XX XX   XX  XXXXX  ' +
        'XX   XX   XXX        XX XX  XX  XX      XXX XXX XXX  XX XX   XX ' +
        'XX   XX   XXX        XX XX XX   XX      XXXXXXX XXXX XX XX   XX ' +
        'XXXXXXX   XXX        XX XXXX    XX      XX X XX XXXXXXX XX   XX ' +
        'XX   XX   XXX   XX   XX XX XX   XX      XX   XX XX XXXX XX   XX ' +
        'XX   XX   XXX   XX   XX XX  XX  XX      XX   XX XX  XXX XX   XX ' +
        'XX   XX XXXXXXX  XXXXX  XX   XX XXXXXXX XX   XX XX   XX  XXXXX  ' +
        '                                                                ' +

        'XXXXXX   XXXXX  XXXXXX   XXXXX  XXXXXXX XX   XX XX   XX XX   XX ' +
        'XX   XX XX   XX XX   XX XX   XX   XXX   XX   XX XX   XX XX   XX ' +
        'XX   XX XX   XX XX   XX XX        XXX   XX   XX XX   XX XX   XX ' +
        'XXXXXX  XX   XX XXXXXX   XXXXX    XXX   XX   XX XX   XX XX   XX ' +
        'XX      XXXX XX XX   XX      XX   XXX   XX   XX XX   XX XX X XX ' +
        'XX      XX XXX  XX   XX XX   XX   XXX   XX   XX  XX XX  XX X XX ' +
        'XX       XXX XX XX   XX  XXXXX    XXX    XXXXX    XXX    XX XX  ' +
        '                                                                ' +

        'XX   XX XX   XX XXXXXXX  XXXXX           XXXXX     XX           ' +
        'XX   XX XX   XX      XX  XX     XX          XX    XXXX          ' +
        ' XX XX   XX XX      XX   XX      XX         XX   XX  XX         ' +
        '  XXX     XXX     XXX    XX       XX        XX                  ' +
        ' XX XX    XXX    XX      XX        XX       XX                  ' +
        'XX   XX   XXX   XX       XX         XX      XX                  ' +
        'XX   XX   XXX   XXXXXXX  XXXXX       XX  XXXXX                  ' +
        '                                                        XXXXXXX ' +

        '  XX            XX                   XX            XXXX         ' +
        '   XX           XX                   XX           XX            ' +
        '         XXXXXX XX       XXXXX       XX  XXXX     XX     XXXXX  ' +
        '        XX   XX XXXXXX  XX       XXXXXX XX  XX  XXXXXXX XX   XX ' +
        '        XX   XX XX   XX XX      XX   XX XXXXXX    XX    XX   XX ' +
        '        XX   XX XX   XX XX      XX   XX XX        XX     XXXXXX ' +
        '         XXXXXX XXXXXX   XXXXX   XXXXXX  XXXXX    XX         XX ' +
        '                                                         XXXXX  ' +

        'XX        XX       XX   XX        XXX                           ' +
        'XX                      XX   XX    XX                           ' +
        'XXXXXX   XXX      XXXX  XX  XX     XX   XXXXXX  XXXXXX   XXXXX  ' +
        'XX   XX   XX        XX  XXXXX      XX   XX X XX XX   XX XX   XX ' +
        'XX   XX   XX        XX  XX  XX     XX   XX X XX XX   XX XX   XX ' +
        'XX   XX   XX        XX  XX   XX    XX   XX X XX XX   XX XX   XX ' +
        'XX   XX  XXXX       XX  XX   XX   XXXX  XX X XX XX   XX  XXXXX  ' +
        '                  XXX                                           ' +

        '                                                                ' +
        '                                  XX                            ' +
        'XXXXXX   XXXXX  XX XXX   XXXXXX   XX    XX   XX XX   XX XX   XX ' +
        'XX   XX XX  XX  XXXX XX XX      XXXXXXX XX   XX XX   XX XX   XX ' +
        'XX   XX XX  XX  XX       XXXXX    XX    XX   XX XX   XX XX X XX ' +
        'XXXXXX   XXXXX  XX           XX   XX XX XX   XX  XX XX  XX X XX ' +
        'XX          XX  XX      XXXXXX     XXX   XXXXXX   XXX    XXXXX  ' +
        'XX          XX                                                  ' +

        '                             XX   XX    XX                 X    ' +
        '                           XX     XX      XX     XXX XX   XXX   ' +
        'XX   XX XX   XX XXXXXXX    XX     XX      XX    XX XXX   XX XX  ' +
        ' XX XX  XX   XX    XXX    XX      XX       XX           XX   XX ' +
        '  XXX   XX   XX   XXX      XX     XX      XX            XX   XX ' +
        ' XX XX   XXXXXX  XXX       XX     XX      XX            XX   XX ' +
        'XX   XX      XX XXXXXXX      XX   XX    XX              XXXXXXX ' +
        '         XXXXX                                                  ' +

        ' XXXXXX                                                  XXXXXX ' +
        'XX      XX   XX                                         XX      ' +
        'XX               XXXX    XXXXXX  XXXXXX  XXXXX   XXXXXX XX      ' +
        'XX      XX   XX XX  XX  XX   XX XX   XX XX   XX XX   XX XX      ' +
        'XX      XX   XX XXXXXX  XX   XX XX   XX XX   XX XX   XX XX      ' +
        'XX      XX   XX XX      XX   XX XX   XX XX   XX XX   XX XX      ' +
        ' XXXXXX  XXXXXX  XXXXX   XXXXXX  XXXXXX  XXXXXX  XXXXXX  XXXXXX ' +
        '                                                                ' +

        '                          XX      XX      XX      XXX     XXX   ' +
        '                          XX      XX      XX     XX XX   XX XX  ' +
        ' XXXX    XXXX    XXXX                           XX   XX XX   XX ' +
        'XX  XX  XX  XX  XX  XX   XXX     XXX     XXX    XXXXXXX XXXXXXX ' +
        'XXXXXX  XXXXXX  XXXXXX    XX      XX      XX    XX   XX XX   XX ' +
        'XX      XX      XX        XX      XX      XX    XX   XX XX   XX ' +
        ' XXXXX   XXXXX   XXXXX   XXXX    XXXX    XXXX   XX   XX XX   XX ' +
        '                                                                ' +

        'XXXXXXX XXXXXXX XXXXXXX                                         ' +
        'XX      XX      XX                                              ' +
        'XX      XX      XX                                              ' +
        'XXXXX   XXXXX   XXXXX    XXXXX   XXXXX   XXXXX  XX   XX XX   XX ' +
        'XX      XX      XX      XX   XX XX   XX XX   XX XX   XX XX   XX ' +
        'XX      XX      XX      XX   XX XX   XX XX   XX XX   XX XX   XX ' +
        'XXXXXXX XXXXXXX XXXXXXX  XXXXX   XXXXX   XXXXX   XXXXXX  XXXXXX ' +
        '                                                                ' +

        '         XXXXX  XX   XX  XXXXXX  XXXXXX  XXXXXX  XXXXXX  XXXXXX ' +
        '        XX   XX XX   XX XX      XX      XX      XX      XX      ' +
        'XX   XX XX   XX XX   XX XX      XX      XX      XX      XX      ' +
        'XX   XX XX   XX XX   XX XX      XX      XX      XX      XX      ' +
        'XX   XX XX   XX XX   XX XX      XX      XX      XX      XX      ' +
        ' XXXXXX XX   XX XX   XX XX      XX      XX      XX      XX      ' +
        '     XX  XXXXX   XXXXX   XXXXXX  XXXXXX  XXXXXX  XXXXXX  XXXXXX ' +
        ' XXXXX                                                          ' +

        '          XX                                                    ' +
        '          XX                                                    ' +
        ' XXXXXX          XXXXX  XX   XX XXXXXX  XXXXXX   XXXXXX  XXXXX  ' +
        'XX   XX  XXX    XX   XX XX   XX XX   XX XX   XX XX   XX XX   XX ' +
        'XX   XX   XX    XX   XX XX   XX XX   XX XX   XX XX   XX XX   XX ' +
        'XX   XX   XX    XX   XX XX   XX XX   XX XX   XX XX   XX XX   XX ' +
        ' XXXXXX  XXXX    XXXXX   XXXXXX XX   XX XX   XX  XXXXXX  XXXXX  ' +
        '                                                                ' +

        '   XX                   X       X          XX                   ' +
        '                        X  X    X  X              XX XX XX XX   ' +
        '   XX                     X       X        XX    XX XX   XX XX  ' +
        ' XXX    XXXXXXX XXXXXXX  X XX    X XX      XX   XX XX     XX XX ' +
        'XX      XX           XX      X       X     XX    XX XX   XX XX  ' +
        'XX   XX XX           XX     X       X      XX     XX XX XX XX   ' +
        ' XXXXX                     XXXX    XXXX    XX                   ' +
        '                                                                ' +

        'X   X    X X X X XXX XXX   X       X       X      X X           ' +
        '  X   X X X X X XX XXX X   X       X       X      X X           ' +
        'X   X    X X X X XXX XXX   X       X    XXXX      X X           ' +
        '  X   X X X X X XX XXX X   X    XXXX       X    XXX X   XXXXX   ' +
        'X   X    X X X X XXX XXX   X       X    XXXX      X X     X X   ' +
        '  X   X X X X X XX XXX X   X       X       X      X X     X X   ' +
        'X   X    X X X X XXX XXX   X       X       X      X X     X X   ' +
        '  X   X X X X X XX XXX X   X       X       X      X X     X X   ' +

        '          X X     X X             X X     X X      X            ' +
        '          X X     X X             X X     X X      X            ' +
        'XXXX    XXX X     X X   XXXXX   XXX X     X X   XXXX            ' +
        '   X        X     X X       X       X   XXXXX      X    XXXX    ' +
        'XXXX    XXX X     X X   XXX X   XXXXX           XXXX       X    ' +
        '   X      X X     X X     X X                              X    ' +
        '   X      X X     X X     X X                              X    ' +
        '   X      X X     X X     X X                              X    ' +

        '   X       X               X               X       X      X X   ' +
        '   X       X               X               X       X      X X   ' +
        '   X       X               X               X       XXXXX  X X   ' +
        '   XXXXXXXXXXXXXXXXXXXXX   XXXXXXXXXXXXXXXXXXXXX   X      X XXXX' +
        '                   X       X               X       XXXXX  X X   ' +
        '                   X       X               X       X      X X   ' +
        '                   X       X               X       X      X X   ' +
        '                   X       X               X       X      X X   ' +

        '  X X             X X             X X             X X      X    ' +
        '  X X             X X             X X             X X      X    ' +
        '  X XXXX  XXXXXXXXX XXXXXXXXXXXX  X XXXXXXXXXXXXXXX XXXXXXXXXXXX' +
        '  X       X                       X                             ' +
        '  XXXXXX  X XXXXXXXXXXXXXXX XXXX  X XXXXXXXXXXXXXXX XXXXXXXXXXXX' +
        '          X X             X X     X X             X X           ' +
        '          X X             X X     X X             X X           ' +
        '          X X             X X     X X             X X           ' +

        '  X X                     X X      X                      X X   ' +
        '  X X                     X X      X                      X X   ' +
        '  X X   XXXXXXXX          X X      XXXXX   XXXXX          X X   ' +
        'XXXXXXXX        XXXXXXXX  XXXXXX   X       X      XXXXXXXXXXXXXX' +
        '        XXXXXXXX  X X              XXXXX   XXXXX  X X     X X   ' +
        '           X      X X                      X      X X     X X   ' +
        '           X      X X                      X      X X     X X   ' +
        '           X      X X                      X      X X     X X   ' +

        '   X       X            XXXXXXXX        XXXX        XXXXXXXXXXXX' +
        '   X       X            XXXXXXXX        XXXX        XXXXXXXXXXXX' +
        'XXXXXXXX   X            XXXXXXXX        XXXX        XXXXXXXXXXXX' +
        '        XXXX       XXXXXXXXXXXXX        XXXX        XXXXXXXXXXXX' +
        'XXXXXXXX           X    XXXXXXXXXXXXXXXXXXXX        XXXX        ' +
        '   X               X    XXXXXXXXXXXXXXXXXXXX        XXXX        ' +
        '   X               X    XXXXXXXXXXXXXXXXXXXX        XXXX        ' +
        '   X               X    XXXXXXXXXXXXXXXXXXXX        XXXX        ' +

        '          XXX    XXXXXX          XXXXXX                         ' +
        ' XX   X  X   X   X               X                              ' +
        'X  X X   X  X    X                X                             ' +
        'X   X    XXXXX   X       XXXXXX    X     XXXXXX                 ' +
        'X  X X   X    X  X        X  X    X     X    X                  ' +
        ' XX   X  X    X  X        X  X   X      X    X                  ' +
        '        X XXXX   X        X  X   XXXXXX  XXXX                   ' +
        '                                                                ' +

        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '                                                                ' +

        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '                                                                ' +

        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXX XXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XX   XX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXX XXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XX   XX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXX XXX XXXXXXX XXXXXXX ' +
        'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
        '                                                                ' +
        '';

      if (height == 8) {
        return LoadFont(FONT8, 1);
      } else if (height == 16) {
        return LoadFont(FONT8, 2);
      } else {
        return RenderFont(ctx, height);
      }
    }

    bindings.statement_screen_iIII(0);
    InitEvents();
    Render();
    return bindings;
  }

  var basic = {
    Basic: Basic,
    GraphicsBindings: GraphicsBindings,
    ConsoleBindings: ConsoleBindings,
  };

  // ESM:
  Main();
// ESM: export default basic;
})();