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PRIVATE: first version of bytecode decompiler

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Meant to be compiled as standalone tool. Not yet integrated
into game engine.
This commit is contained in:
Francisco Javier Diéguez Tirado 2021-04-19 01:30:08 +02:00 committed by Eugene Sandulenko
parent 40f6c70841
commit f10fb7fbad
2 changed files with 175 additions and 0 deletions
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66
engines/private/decompiler.cpp Normal file
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#include <fstream>
#include <sstream>
#include "decompiler.h"
namespace Private {
Decompiler::~Decompiler() {
}
Decompiler::Decompiler(const std::string &fileName, bool mac) {
std::ifstream infile(fileName);
if (!infile.good())
throw std::invalid_argument("File does not exist");
std::ifstream input(fileName, std::ios::binary);
std::vector<unsigned char> buffer(std::istreambuf_iterator<char>(input), {});
decompile(buffer, mac);
}
Decompiler::Decompiler(std::vector<unsigned char> &buffer, bool mac) {
decompile(buffer, mac);
}
void Decompiler::decompile(std::vector<unsigned char> &buffer, bool mac) {
std::vector<unsigned char>::iterator it = buffer.begin();
std::string firstBytes(it, it + kHeader.length());
if (firstBytes != kHeader) {
throw std::invalid_argument("Not a precompiled game matrix");
}
std::stringstream ss;
bool inDefineRects = false;
for (it += kHeader.length() ; it != buffer.end() ; ) {
unsigned char byte = *it++;
if (byte == kCodeString) {
unsigned char len = *it++;
std::string s(it,it+len);
it += len;
ss << "\"" << s << "\"";
} else if (byte == kCodeShortLiteral || byte == kCodeShortId) {
unsigned char b1 = *it++;
unsigned char b2 = *it++;
unsigned int number = mac ? b2 + (b1 << 8) : b1 + (b2 << 8);
if (byte == kCodeShortId) ss << "k";
ss << number;
} else if (byte == kCodeRect && inDefineRects) {
ss << "RECT"; // override CRect
} else if (byte <= kCodeShortId && kCodeTable[byte].length() > 0) {
ss << kCodeTable[byte];
} else {
throw std::invalid_argument("Unknown byte code");
}
if (byte == kCodeRects) {
inDefineRects = true;
} else if (byte == kCodeBraceClose && inDefineRects) {
inDefineRects = false;
}
}
_result = ss.str();
}
void Decompiler::getResult(std::string &result) const {
result = _result;
}
}

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#include <vector>
#include <string>
namespace Private {
const std::string kHeader("Precompiled Game Matrix");
const unsigned char kCodeString = 0x01;
const unsigned char kCodeShortLiteral = 0x02;
const unsigned char kCodeBraceClose = 0x04;
const unsigned char kCodeRect = 0x2e;
const unsigned char kCodeRects = 0x4f;
const unsigned char kCodeShortId = 0x50;
const std::vector<std::string> kCodeTable = {"", //
"", // 0x01 (string)
"", // 0x02 (short literal)
" {\n", // 0x03
"}\n", // 0x04
"(", // 0x05
")", // 0x06
"", //
"", //
"", //
",", // 0x0a
"", //
"%", // 0x0c
"", //
";\n", // 0x0e
"!", // 0x0f
"-", // 0x10
"+", // 0x11
"=", // 0x12
">", // 0x13
"<", // 0x14
"if ", // 0x15
"else ", // 0x16
"Exit", // 0x17
"goto", // 0x18
"Mask", // 0x19
"MaskDrawn", // 0x1a
"Movie", // 0x1b
"Transition", // 0x1c
"ThumbnailMovie", // 0x1d
"BustMovie", // 0x1e
"ViewScreen", // 0x1f
"VSPicture", // 0x20
"Bitmap", // 0x21
"Timer", // 0x22
"SoundArea", // 0x23
"Sound", // 0x24
"SoundEffect", // 0x25
"SyncSound", // 0x26
"LoopedSound", // 0x27
"NoStopSounds", // 0x28
"Resume", // 0x29
"Inventory", // 0x2a
"SetFlag", // 0x2b
"ChgMode", // 0x2c
"PoliceBust", // 0x2d
"CRect", // 0x2e overridden with "RECT" if in "define rects" block
"", //
"Random", // 0x30
"SafeDigit", // 0x31
"LoseInventory", // 0x32
"", //
"PaperShuffleSound", // 0x34
"Quit", // 0x35
"DossierAdd", // 0x36
"DossierBitmap", // 0x37
"DossierPrevSuspect", // 0x38
"DossierNextSuspect", // 0x39
"DossierChgSheet", // 0x3a
"DiaryLocList", // 0x3b
"DiaryPage", // 0x3c
"DiaryInvList", // 0x3d
"DiaryPageTurn", // 0x3e
"DiaryGoLoc", // 0x3f
"SaveGame", // 0x40
"LoadGame", // 0x41
"RestartGame", // 0x42
"AskSave", // 0x43
"SetModifiedFlag", // 0x44
"PhoneClip", // 0x45
"PoliceClip", // 0x46
"AMRadioClip", // 0x47
"\nsetting ", // 0x48
"debug ", // 0x49
"\ndefine ", // 0x4a
"", //
"variables", // 0x4c
"", //
"", //
"rects", // 0x4f
""}; // 0x50 (short id)
class Decompiler {
public:
Decompiler(const std::string &filename, bool mac = false);
Decompiler(std::vector<unsigned char> &buffer, bool mac = false);
virtual ~Decompiler();
void getResult(std::string &result) const;
private:
void decompile(std::vector<unsigned char> &buffer, bool mac);
std::string _result;
};
}