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Standardise repetitive sign/zero/parity sets.
This commit is contained in:
Thomas Harte
parent
fbd647080d
commit
033ba75376
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@ -198,8 +198,7 @@ inline void aad(CPU::RegisterPair16 &ax, uint8_t imm, Status &status) {
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*/
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ax.halves.low = ax.halves.low + (ax.halves.high * imm);
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ax.halves.high = 0;
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status.sign = ax.halves.low & 0x80;
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status.parity = status.zero = ax.halves.low;
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status.set_from<uint8_t, Flag::Zero, Flag::Sign, Flag::ParityOdd>(ax.halves.low);
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}
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template <typename FlowControllerT>
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@ -223,8 +222,7 @@ inline void aam(CPU::RegisterPair16 &ax, uint8_t imm, Status &status, FlowContro
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ax.halves.high = ax.halves.low / imm;
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ax.halves.low = ax.halves.low % imm;
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status.sign = ax.halves.low & 0x80;
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status.parity = status.zero = ax.halves.low;
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status.set_from<uint8_t, Flag::Zero, Flag::Sign, Flag::ParityOdd>(ax.halves.low);
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}
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inline void aas(CPU::RegisterPair16 &ax, Status &status) {
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@ -303,8 +301,7 @@ inline void daa(uint8_t &al, Status &status) {
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status.carry = 0;
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}
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status.sign = al & 0x80;
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status.zero = status.parity = al;
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status.set_from<uint8_t, Flag::Zero, Flag::Sign, Flag::ParityOdd>(al);
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}
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inline void das(uint8_t &al, Status &status) {
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@ -355,8 +352,7 @@ inline void das(uint8_t &al, Status &status) {
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status.carry = 0;
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}
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status.sign = al & 0x80;
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status.zero = status.parity = al;
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status.set_from<uint8_t, Flag::Zero, Flag::Sign, Flag::ParityOdd>(al);
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}
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template <bool with_carry, typename IntT>
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@ -371,10 +367,10 @@ void add(IntT &destination, IntT source, Status &status) {
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status.carry = Numeric::carried_out<true, Numeric::bit_size<IntT>() - 1>(destination, source, result);
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status.auxiliary_carry = Numeric::carried_in<4>(destination, source, result);
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status.sign = result & Numeric::top_bit<IntT>();
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status.zero = status.parity = result;
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status.overflow = Numeric::overflow<true, IntT>(destination, source, result);
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(result);
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destination = result;
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}
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@ -390,10 +386,10 @@ void sub(IntT &destination, IntT source, Status &status) {
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status.carry = Numeric::carried_out<false, Numeric::bit_size<IntT>() - 1>(destination, source, result);
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status.auxiliary_carry = Numeric::carried_in<4>(destination, source, result);
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status.sign = result & Numeric::top_bit<IntT>();
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status.zero = status.parity = result;
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status.overflow = Numeric::overflow<false, IntT>(destination, source, result);
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(result);
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if constexpr (write_back) {
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destination = result;
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}
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@ -419,10 +415,8 @@ void test(IntT &destination, IntT source, Status &status) {
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*/
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const IntT result = destination & source;
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status.sign = result & Numeric::top_bit<IntT>();
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status.zero = result;
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status.carry = status.overflow = 0;
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status.parity = result;
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(result);
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}
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template <typename IntT>
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@ -617,9 +611,8 @@ void inc(IntT &destination, Status &status) {
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++destination;
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status.overflow = destination == Numeric::top_bit<IntT>();
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status.sign = destination & Numeric::top_bit<IntT>();
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status.zero = status.parity = destination;
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status.auxiliary_carry = ((destination - 1) ^ destination) & 0x10;
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
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}
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template <typename IntT, typename RegistersT, typename FlowControllerT>
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@ -654,8 +647,7 @@ void dec(IntT &destination, Status &status) {
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--destination;
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status.sign = destination & Numeric::top_bit<IntT>();
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status.zero = status.parity = destination;
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
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status.auxiliary_carry = ((destination + 1) ^ destination) & 0x10;
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}
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@ -672,8 +664,7 @@ void and_(IntT &destination, IntT source, Status &status) {
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status.overflow = 0;
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status.carry = 0;
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status.sign = destination & Numeric::top_bit<IntT>();
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status.zero = status.parity = destination;
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
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}
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template <typename IntT>
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@ -689,8 +680,7 @@ void or_(IntT &destination, IntT source, Status &status) {
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status.overflow = 0;
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status.carry = 0;
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status.sign = destination & Numeric::top_bit<IntT>();
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status.zero = status.parity = destination;
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
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}
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template <typename IntT>
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@ -706,8 +696,7 @@ void xor_(IntT &destination, IntT source, Status &status) {
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status.overflow = 0;
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status.carry = 0;
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status.sign = destination & Numeric::top_bit<IntT>();
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status.zero = status.parity = destination;
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
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}
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template <typename IntT>
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@ -729,8 +718,7 @@ void neg(IntT &destination, Status &status) {
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status.carry = destination;
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status.overflow = destination == Numeric::top_bit<IntT>();
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status.sign = destination & Numeric::top_bit<IntT>();
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status.zero = status.parity = destination;
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status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
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}
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template <typename IntT>
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@ -958,112 +946,112 @@ template <
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case Operation::JO:
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Primitive::jump(
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status.condition<Status::Condition::Overflow>(),
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status.condition<Condition::Overflow>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JNO:
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Primitive::jump(
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!status.condition<Status::Condition::Overflow>(),
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!status.condition<Condition::Overflow>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JB:
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Primitive::jump(
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status.condition<Status::Condition::Below>(),
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status.condition<Condition::Below>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JNB:
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Primitive::jump(
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!status.condition<Status::Condition::Below>(),
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!status.condition<Condition::Below>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JZ:
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Primitive::jump(
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status.condition<Status::Condition::Zero>(),
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status.condition<Condition::Zero>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JNZ:
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Primitive::jump(
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!status.condition<Status::Condition::Zero>(),
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!status.condition<Condition::Zero>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JBE:
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Primitive::jump(
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status.condition<Status::Condition::BelowOrEqual>(),
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status.condition<Condition::BelowOrEqual>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JNBE:
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Primitive::jump(
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!status.condition<Status::Condition::BelowOrEqual>(),
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!status.condition<Condition::BelowOrEqual>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JS:
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Primitive::jump(
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status.condition<Status::Condition::Sign>(),
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status.condition<Condition::Sign>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JNS:
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Primitive::jump(
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!status.condition<Status::Condition::Sign>(),
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!status.condition<Condition::Sign>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JP:
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Primitive::jump(
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!status.condition<Status::Condition::ParityOdd>(),
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!status.condition<Condition::ParityOdd>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JNP:
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Primitive::jump(
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status.condition<Status::Condition::ParityOdd>(),
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status.condition<Condition::ParityOdd>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JL:
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Primitive::jump(
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status.condition<Status::Condition::Less>(),
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status.condition<Condition::Less>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JNL:
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Primitive::jump(
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!status.condition<Status::Condition::Less>(),
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!status.condition<Condition::Less>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JLE:
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Primitive::jump(
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status.condition<Status::Condition::LessOrEqual>(),
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status.condition<Condition::LessOrEqual>(),
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instruction.displacement(),
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registers,
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flow_controller);
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return;
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case Operation::JNLE:
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Primitive::jump(
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!status.condition<Status::Condition::LessOrEqual>(),
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!status.condition<Condition::LessOrEqual>(),
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instruction.displacement(),
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registers,
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flow_controller);
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@ -9,6 +9,7 @@
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#ifndef InstructionSets_x86_Status_hpp
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#define InstructionSets_x86_Status_hpp
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#include "../../Numeric/Carry.hpp"
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namespace InstructionSet::x86 {
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@ -53,6 +54,29 @@ static constexpr uint32_t VirtualMode = 1 << 17;
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}
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enum class Flag {
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Carry,
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AuxiliaryCarry,
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Sign,
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Overflow,
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Trap,
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Interrupt,
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Direction,
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Zero,
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ParityOdd
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};
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enum class Condition {
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Overflow,
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Below,
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Zero,
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BelowOrEqual,
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Sign,
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ParityOdd,
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Less,
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LessOrEqual
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};
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struct Status {
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// Non-zero => set; zero => unset.
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uint32_t carry;
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@ -70,17 +94,6 @@ struct Status {
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uint32_t parity;
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// Flag getters.
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enum class Flag {
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Carry,
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AuxiliaryCarry,
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Sign,
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Overflow,
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Trap,
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Interrupt,
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Direction,
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Zero,
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ParityOdd
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};
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template <Flag flag> bool flag() {
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switch(flag) {
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case Flag::Carry: return carry;
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@ -96,16 +109,6 @@ struct Status {
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}
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// Condition evaluation.
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enum class Condition {
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Overflow,
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Below,
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Zero,
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BelowOrEqual,
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Sign,
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ParityOdd,
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Less,
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LessOrEqual
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};
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template <Condition test> bool condition() {
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switch(test) {
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case Condition::Overflow: return flag<Flag::Overflow>();
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@ -119,6 +122,18 @@ struct Status {
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}
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}
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// Convenience setters.
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template <typename IntT, Flag... flags> void set_from(IntT value) {
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for(const auto flag: {flags...}) {
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switch(flag) {
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default: break;
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case Flag::Zero: zero = value; break;
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case Flag::Sign: sign = value & Numeric::top_bit<IntT>(); break;
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case Flag::ParityOdd: parity = value; break;
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}
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}
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}
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template <typename IntT> IntT carry_bit() const { return carry ? 1 : 0; }
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bool not_parity_bit() const {
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// x86 parity always considers the lowest 8-bits only.
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