octarect / emu_x86 Goto Github PK

void set_register8(Emulator* emu, int index, uint8_t value)
{
  if (index < 4) {
    uint32_t r = emu->registers[index] & 0xffffff00;
    emu->registers[index] = r | (uint32_t)value;
  } else {
    uint32_t r = emu->registers[index] & 0xffff00ff;
    emu->registers[index - 4] = r | ((uint32_t)value << 8);
  }
}

void set_register8(Emulator* emu, int index, uint8_t value)
{
  if (index < 4) {
    uint32_t r = emu->registers[index] & 0xffffff00;
    emu->registers[index] = r | (uint32_t)value;
  } else {
    uint32_t r = emu->registers[index - 4] & 0xffff00ff;
    emu->registers[index - 4] = r | ((uint32_t)value << 8);
  }
}

uint32_t eval_sib(Emulator* emu, ModRM* modrm) {
    uint8_t sib = modrm->sib;
    uint8_t scale = (sib >> 6) & 0x03;   //((sib & 0xC0) >> 6); //old broken code
    uint8_t base  = sib & 0x07;          //((sib & 0x38) >> 3); //old broken code
    uint8_t index = (sib >> 3) & 0x07;   //(sib & 0x03);         //old broken code

  7   6   5   4   3   2   1   0
+---+---+---+---+---+---+---+---+
|  mod  |    reg    |     rm    |
+---+---+---+---+---+---+---+---+

    modrm->mod = (code >> 6) & 0x03;     //old code  ((code & 0xC0) >> 6);
    modrm->opcode = (code >> 3) & 0x07;  //old code  ((code & 0x38) >> 3);
    modrm->rm = code & 0x07;             //old code  code & 0x07;