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// Copyright 2013 Dolphin Emulator Project
// Licensed under GPLv2
// Refer to the license.txt file included.
#include "x64Analyzer.h"
bool DisassembleMov(const unsigned char *codePtr, InstructionInfo *info)
{
unsigned const char *startCodePtr = codePtr;
u8 rex = 0;
u8 codeByte = 0;
u8 codeByte2 = 0;
//Check for regular prefix
info->operandSize = 4;
info->zeroExtend = false;
info->signExtend = false;
info->hasImmediate = false;
info->isMemoryWrite = false;
u8 modRMbyte = 0;
u8 sibByte = 0;
bool hasModRM = false;
int displacementSize = 0;
if (*codePtr == 0x66)
{
info->operandSize = 2;
codePtr++;
}
else if (*codePtr == 0x67)
{
codePtr++;
}
//Check for REX prefix
if ((*codePtr & 0xF0) == 0x40)
{
rex = *codePtr;
if (rex & 8) //REX.W
{
info->operandSize = 8;
}
codePtr++;
}
codeByte = *codePtr++;
// Skip two-byte opcode byte
bool twoByte = false;
if(codeByte == 0x0F)
{
twoByte = true;
codeByte2 = *codePtr++;
}
if (!twoByte)
{
if ((codeByte & 0xF0) == 0x80 ||
((codeByte & 0xF8) == 0xC0 && (codeByte & 0x0E) != 0x02))
{
modRMbyte = *codePtr++;
hasModRM = true;
}
}
else
{
if (((codeByte2 & 0xF0) == 0x00 && (codeByte2 & 0x0F) >= 0x04 && (codeByte2 & 0x0D) != 0x0D) ||
(codeByte2 & 0xF0) == 0x30 ||
codeByte2 == 0x77 ||
(codeByte2 & 0xF0) == 0x80 ||
((codeByte2 & 0xF0) == 0xA0 && (codeByte2 & 0x07) <= 0x02) ||
(codeByte2 & 0xF8) == 0xC8)
{
// No mod R/M byte
}
else
{
modRMbyte = *codePtr++;
hasModRM = true;
}
}
if (hasModRM)
{
ModRM mrm(modRMbyte, rex);
info->regOperandReg = mrm.reg;
if (mrm.mod < 3)
{
if (mrm.rm == 4)
{
//SIB byte
sibByte = *codePtr++;
info->scaledReg = (sibByte >> 3) & 7;
info->otherReg = (sibByte & 7);
if (rex & 2) info->scaledReg += 8;
if (rex & 1) info->otherReg += 8;
}
else
{
//info->scaledReg =
}
}
if (mrm.mod == 1 || mrm.mod == 2)
{
if (mrm.mod == 1)
displacementSize = 1;
else
displacementSize = 4;
}
}
if (displacementSize == 1)
info->displacement = (s32)(s8)*codePtr;
else
info->displacement = *((s32 *)codePtr);
codePtr += displacementSize;
switch (codeByte)
{
// writes
case 0xC6: // mem <- imm8
{
info->isMemoryWrite = true;
info->hasImmediate = true;
info->immediate = *codePtr;
codePtr++; //move past immediate
}
break;
case 0xC7: // mem <- imm16/32
{
info->isMemoryWrite = true;
if (info->operandSize == 2)
{
info->hasImmediate = true;
info->immediate = *(u16*)codePtr;
codePtr += 2;
}
else if (info->operandSize == 4)
{
info->hasImmediate = true;
info->immediate = *(u32*)codePtr;
codePtr += 4;
}
else if (info->operandSize == 8)
{
info->zeroExtend = true;
info->immediate = *(u32*)codePtr;
codePtr += 4;
}
}
case 0x89: // mem <- r16/32/64
{
info->isMemoryWrite = true;
break;
}
case 0x0F: // two-byte escape
{
info->isMemoryWrite = false;
switch (codeByte2)
{
case 0xB6: // movzx on byte
info->zeroExtend = true;
info->operandSize = 1;
break;
case 0xB7: // movzx on short
info->zeroExtend = true;
info->operandSize = 2;
break;
case 0xBE: // movsx on byte
info->signExtend = true;
info->operandSize = 1;
break;
case 0xBF: // movsx on short
info->signExtend = true;
info->operandSize = 2;
break;
default:
return false;
}
break;
}
case 0x8A: // r8 <- mem
{
info->isMemoryWrite = false;
if (info->operandSize == 4)
{
info->operandSize = 1;
break;
}
else
return false;
}
case 0x8B: // r16/32/64 <- mem
{
info->isMemoryWrite = false;
break;
}
break;
default:
return false;
}
info->instructionSize = (int)(codePtr - startCodePtr);
return true;
}
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