int DisassemblerX64::registerFPUInstruction()

in runtime/disassembler-x64.cpp [912:1090]

• 169 lines of code
• 46 McCabe index (conditional complexity)

int DisassemblerX64::registerFPUInstruction(int escape_opcode,
                                            uint8_t modrm_byte) {
  bool has_register = false;  // Is the FPU register encoded in modrm_byte?
  const char* mnem = "?";

  switch (escape_opcode) {
    case 0xD8:
      unimplementedInstruction();
      break;

    case 0xD9:
      switch (modrm_byte & 0xF8) {
        case 0xC0:
          mnem = "fld";
          has_register = true;
          break;
        case 0xC8:
          mnem = "fxch";
          has_register = true;
          break;
        default:
          switch (modrm_byte) {
            case 0xE0:
              mnem = "fchs";
              break;
            case 0xE1:
              mnem = "fabs";
              break;
            case 0xE3:
              mnem = "fninit";
              break;
            case 0xE4:
              mnem = "ftst";
              break;
            case 0xE8:
              mnem = "fld1";
              break;
            case 0xEB:
              mnem = "fldpi";
              break;
            case 0xED:
              mnem = "fldln2";
              break;
            case 0xEE:
              mnem = "fldz";
              break;
            case 0xF0:
              mnem = "f2xm1";
              break;
            case 0xF1:
              mnem = "fyl2x";
              break;
            case 0xF2:
              mnem = "fptan";
              break;
            case 0xF5:
              mnem = "fprem1";
              break;
            case 0xF7:
              mnem = "fincstp";
              break;
            case 0xF8:
              mnem = "fprem";
              break;
            case 0xFB:
              mnem = "fsincos";
              break;
            case 0xFD:
              mnem = "fscale";
              break;
            case 0xFE:
              mnem = "fsin";
              break;
            case 0xFF:
              mnem = "fcos";
              break;
            default:
              unimplementedInstruction();
          }
      }
      break;

    case 0xDA:
      if (modrm_byte == 0xE9) {
        mnem = "fucompp";
      } else {
        unimplementedInstruction();
      }
      break;

    case 0xDB:
      if ((modrm_byte & 0xF8) == 0xE8) {
        mnem = "fucomi";
        has_register = true;
      } else if (modrm_byte == 0xE2) {
        mnem = "fclex";
      } else {
        unimplementedInstruction();
      }
      break;

    case 0xDC:
      has_register = true;
      switch (modrm_byte & 0xF8) {
        case 0xC0:
          mnem = "fadd";
          break;
        case 0xE8:
          mnem = "fsub";
          break;
        case 0xC8:
          mnem = "fmul";
          break;
        case 0xF8:
          mnem = "fdiv";
          break;
        default:
          unimplementedInstruction();
      }
      break;

    case 0xDD:
      has_register = true;
      switch (modrm_byte & 0xF8) {
        case 0xC0:
          mnem = "ffree";
          break;
        case 0xD8:
          mnem = "fstp";
          break;
        default:
          unimplementedInstruction();
      }
      break;

    case 0xDE:
      if (modrm_byte == 0xD9) {
        mnem = "fcompp";
      } else {
        has_register = true;
        switch (modrm_byte & 0xF8) {
          case 0xC0:
            mnem = "faddp";
            break;
          case 0xE8:
            mnem = "fsubp";
            break;
          case 0xC8:
            mnem = "fmulp";
            break;
          case 0xF8:
            mnem = "fdivp";
            break;
          default:
            unimplementedInstruction();
        }
      }
      break;

    case 0xDF:
      if (modrm_byte == 0xE0) {
        mnem = "fnstsw_ax";
      } else if ((modrm_byte & 0xF8) == 0xE8) {
        mnem = "fucomip";
        has_register = true;
      }
      break;

    default:
      unimplementedInstruction();
  }

  if (has_register) {
    print("%s st%d", mnem, modrm_byte & 0x7);
  } else {
    print("%s", mnem);
  }
  return 2;
}