Method DecodeNZCVCondition

FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp:573–626

}

std::optional<CondClassType> OpDispatchBuilder::DecodeNZCVCondition(uint8_t OP) {
  switch (OP) {
  case 0x0: { // JO - Jump if OF == 1
    return CondClassType {COND_FU};
  }
  case 0x1: { // JNO - Jump if OF == 0
    return CondClassType {COND_FNU};
  }
  case 0x2: { // JC - Jump if CF == 1
    return CondClassType {CFInverted ? COND_ULT : COND_UGE};
  }
  case 0x3: { // JNC - Jump if CF == 0
    return CondClassType {CFInverted ? COND_UGE : COND_ULT};
  }
  case 0x4: { // JE - Jump if ZF == 1
    return CondClassType {COND_EQ};
  }
  case 0x5: { // JNE - Jump if ZF == 0
    return CondClassType {COND_NEQ};
  }
  case 0x6: { // JNA - Jump if CF == 1 || ZF == 1
    // With CF, we want (C == 0 || Z == 1). By De Morgan's, that's
    // equivalent to !(C == 1 && Z == 0). That's .ls
    RectifyCarryInvert(true);
    return CondClassType {COND_ULE};
  }
  case 0x7: { // JA - Jump if CF == 0 && ZF == 0
    // With CF inverted, we want (C == 1 && Z == 0). That's .hi
    RectifyCarryInvert(true);
    return CondClassType {COND_UGT};
  }
  case 0x8: { // JS - Jump if SF == 1
    return CondClassType {COND_MI};
  }
  case 0x9: { // JNS - Jump if SF == 0
    return CondClassType {COND_PL};
  }
  case 0xC: { // SF <> OF
    return CondClassType {COND_SLT};
  }
  case 0xD: { // SF = OF
    return CondClassType {COND_SGE};
  }
  case 0xE: { // ZF = 1 || SF <> OF
    return CondClassType {COND_SLE};
  }
  case 0xF: { // ZF = 0 && SF = OF
    return CondClassType {COND_SGT};
  }
  default:
    // Other conditions do not map directly, caller gets to deal with it.
    return std::nullopt;
  }
}

static bool ParityJumpIsJP(uint8_t OP) {
  LOGMAN_THROW_A_FMT(OP == 0xA || OP == 0xB, "JP or JNP");