ImageSegment.h

/*
    Copyright (c) 2019-2023 Javier Pimás, Jan Vrany, Labware. 
    See (MIT) license in root directory.
 */

#ifndef _IMAGE_SEGMENT_H_
#define _IMAGE_SEGMENT_H_

#include <cstdint>
#include <map>
#include <string>

#include "HeapObject.h"

namespace Egg
{


typedef struct _ImageSegmentHeader
{
    /**
     * Signature of an Egg Image Segment, must be following sequence:
     * { 'E' , 'G', 'G', '_' , 'I', 'S', '\n', '\0' }
     */
    uint8_t signature[8];
    /**
     * Assumed base address at which segment is loaded, including
     * its segment header. Implementations are free to load segment at
     * any other address in which case object references (including the
     * `entry_point_method` reference!) must be relocated prior use.
     */
    uint64_t baseAddress;
    /**
     * Size of a segment including its header
     */
    uint64_t size;
    /**
     * Amount of memory to be reserved when loading the segment
     */
    uint64_t reservedSize;
    /**
     * A reference to Module instance describing this image segment
     */
    HeapObject* module;

} ImageSegmentHeader;

static_assert(sizeof(ImageSegmentHeader) == 40 /*bytes*/,
              "segment_header size not 40 bytes");

/**
 * Base class for memory segments containing Egg objects.
 * Provides the common interface used by Runtime: memory bounds and exports.
 */
class ImageSegment
{
  public:
    ImageSegmentHeader header;
    uint64_t _currentBase;
    std::map<std::string, HeapObject*> _exports;

    virtual ~ImageSegment() = default;

    uintptr_t spaceStart() { return _currentBase + sizeof(ImageSegmentHeader); }
    uintptr_t spaceEnd() { return _currentBase + header.size; }

    void dumpObjects();
};

} // namespace Egg

#endif // _IMAGE_SEGMENT_H_