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https://github.com/TomHarte/CLK.git
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Perform a prima facie conversion of ADD/SUB[/X] from macros to templates.
This commit is contained in:
Thomas Harte
parent
c0377f074f
commit
58396f0c52
@ -20,14 +20,83 @@ namespace M68k {
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#define u_extend16(x) uint32_t(int16_t(x))
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#define s_extend16(x) int32_t(int16_t(x))
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namespace Primitive {
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/// Provides a type alias, @c type, which is an unsigned int bigger than @c IntT.
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template <typename IntT> struct BiggerInt {};
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template <> struct BiggerInt<uint8_t> {
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using type = uint16_t;
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};
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template <> struct BiggerInt<uint16_t> {
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using type = uint32_t;
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};
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template <> struct BiggerInt<uint32_t> {
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using type = uint64_t;
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};
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/// @returns An int of type @c IntT with only the most-significant bit set.
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template <typename IntT> constexpr IntT top_bit() {
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static_assert(!std::numeric_limits<IntT>::is_signed);
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constexpr IntT max = std::numeric_limits<IntT>::max();
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return max - (max >> 1);
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}
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/// @returns The number of bits in @c IntT.
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template <typename IntT> constexpr int bit_count() {
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return sizeof(IntT) * 8;
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}
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/// @returns An int with the top bit indicating whether overflow occurred when @c source and @c destination
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/// were either added (if @c is_add is true) or subtracted (if @c is_add is false) and the result was @c result.
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/// All other bits will be clear.
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template <bool is_add, typename IntT>
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static Status::FlagT overflow(IntT source, IntT destination, IntT result) {
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const IntT output_changed = result ^ destination;
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const IntT input_differed = source ^ destination;
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if constexpr (is_add) {
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return top_bit<IntT>() & output_changed & ~input_differed;
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} else {
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return top_bit<IntT>() & output_changed & input_differed;
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}
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}
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/// Performs an add or subtract (as per @c is_add) between @c source and @c destination,
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/// updating @c status. @c is_extend indicates whether this is an extend operation (e.g. ADDX)
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/// or a plain one (e.g. ADD).
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template <bool is_add, bool is_extend, typename IntT>
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static void add_sub(IntT source, IntT &destination, Status &status) {
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static_assert(!std::numeric_limits<IntT>::is_signed);
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using BigIntT = typename BiggerInt<IntT>::type;
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const BigIntT extend = (is_extend && status.extend_flag) ? 1 : 0;
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const BigIntT result = is_add ?
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(BigIntT(destination) + BigIntT(source) + extend) :
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(BigIntT(destination) - BigIntT(source) - extend);
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// Extend operations can reset the zero flag only; non-extend operations
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// can either set it or reset it. Which in the reverse-logic world of
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// zero_result means ORing or storing.
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if constexpr (is_extend) {
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status.zero_result |= IntT(result);
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} else {
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status.zero_result = IntT(result);
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}
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status.extend_flag =
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status.carry_flag = Status::FlagT(result >> bit_count<IntT>());
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status.negative_flag = Status::FlagT(result & top_bit<IntT>());
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status.overflow_flag = overflow<is_add>(source, destination, IntT(result));
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destination = IntT(result);
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}
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}
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template <
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Model model,
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typename FlowController,
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Operation operation = Operation::Undefined
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> void perform(Preinstruction instruction, CPU::SlicedInt32 &src, CPU::SlicedInt32 &dest, Status &status, FlowController &flow_controller) {
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#define sub_overflow() ((result ^ destination) & (destination ^ source))
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#define add_overflow() ((result ^ destination) & ~(destination ^ source))
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switch((operation != Operation::Undefined) ? operation : instruction.operation) {
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/*
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ABCD adds the lowest bytes from the source and destination using BCD arithmetic,
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@ -58,159 +127,27 @@ template <
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dest.b = uint8_t(result);
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} break;
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#define addop(a, b, x) a + b + (x ? 1 : 0)
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#define subop(a, b, x) a - b - (x ? 1 : 0)
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#define z_set(a, b) a = b
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#define z_or(a, b) a |= b
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#define addsubb(a, b, op, overflow, x, zero_op) \
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const int source = a; \
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const int destination = b; \
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const auto result = op(destination, source, x); \
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\
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b = uint8_t(result); \
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zero_op(status.zero_result, b); \
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status.extend_flag = status.carry_flag = uint_fast32_t(result & ~0xff); \
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status.negative_flag = result & 0x80; \
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status.overflow_flag = overflow() & 0x80;
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#define addsubw(a, b, op, overflow, x, zero_op) \
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const int source = a; \
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const int destination = b; \
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const auto result = op(destination, source, x); \
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\
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b = uint16_t(result); \
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zero_op(status.zero_result, b); \
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status.extend_flag = status.carry_flag = uint_fast32_t(result & ~0xffff); \
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status.negative_flag = result & 0x8000; \
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status.overflow_flag = overflow() & 0x8000;
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#define addsubl(a, b, op, overflow, x, zero_op) \
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const uint64_t source = a; \
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const uint64_t destination = b; \
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const auto result = op(destination, source, x); \
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\
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b = uint32_t(result); \
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zero_op(status.zero_result, b); \
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status.extend_flag = status.carry_flag = uint_fast32_t(result >> 32); \
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status.negative_flag = result & 0x80000000; \
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status.overflow_flag = overflow() & 0x80000000;
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#define addb(a, b, x, z) addsubb(a, b, addop, add_overflow, x, z)
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#define subb(a, b, x, z) addsubb(a, b, subop, sub_overflow, x, z)
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#define addw(a, b, x, z) addsubw(a, b, addop, add_overflow, x, z)
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#define subw(a, b, x, z) addsubw(a, b, subop, sub_overflow, x, z)
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#define addl(a, b, x, z) addsubl(a, b, addop, add_overflow, x, z)
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#define subl(a, b, x, z) addsubl(a, b, subop, sub_overflow, x, z)
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#define no_extend(op, a, b) op(a, b, 0, z_set)
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#define extend(op, a, b) op(a, b, status.extend_flag, z_or)
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// ADD and ADDA add two quantities, the latter sign extending and without setting any flags;
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// ADDQ and SUBQ act as ADD and SUB, but taking the second argument from the instruction code.
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case Operation::ADDb: {
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no_extend( addb,
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src.b,
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dest.b);
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} break;
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case Operation::ADDb: Primitive::add_sub<true, false>(src.b, dest.b, status); break;
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case Operation::SUBb: Primitive::add_sub<false, false>(src.b, dest.b, status); break;
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case Operation::ADDXb: Primitive::add_sub<true, true>(src.b, dest.b, status); break;
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case Operation::SUBXb: Primitive::add_sub<false, true>(src.b, dest.b, status); break;
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case Operation::ADDXb: {
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extend( addb,
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src.b,
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dest.b);
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} break;
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case Operation::ADDw: Primitive::add_sub<true, false>(src.w, dest.w, status); break;
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case Operation::SUBw: Primitive::add_sub<false, false>(src.w, dest.w, status); break;
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case Operation::ADDXw: Primitive::add_sub<true, true>(src.w, dest.w, status); break;
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case Operation::SUBXw: Primitive::add_sub<false, true>(src.w, dest.w, status); break;
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case Operation::ADDw: {
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no_extend( addw,
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src.w,
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dest.w);
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} break;
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case Operation::ADDl: Primitive::add_sub<true, false>(src.l, dest.l, status); break;
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case Operation::SUBl: Primitive::add_sub<false, false>(src.l, dest.l, status); break;
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case Operation::ADDXl: Primitive::add_sub<true, true>(src.l, dest.l, status); break;
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case Operation::SUBXl: Primitive::add_sub<false, true>(src.l, dest.l, status); break;
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case Operation::ADDXw: {
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extend( addw,
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src.w,
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dest.w);
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} break;
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case Operation::ADDl: {
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no_extend( addl,
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src.l,
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dest.l);
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} break;
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case Operation::ADDXl: {
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extend( addl,
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src.l,
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dest.l);
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} break;
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case Operation::SUBb: {
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no_extend( subb,
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src.b,
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dest.b);
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} break;
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case Operation::SUBXb: {
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extend( subb,
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src.b,
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dest.b);
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} break;
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case Operation::SUBw: {
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no_extend( subw,
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src.w,
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dest.w);
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} break;
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case Operation::SUBXw: {
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extend( subw,
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src.w,
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dest.w);
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} break;
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case Operation::SUBl: {
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no_extend( subl,
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src.l,
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dest.l);
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} break;
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case Operation::SUBXl: {
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extend( subl,
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src.l,
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dest.l);
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} break;
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#undef addl
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#undef addw
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#undef addb
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#undef subl
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#undef subw
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#undef subb
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#undef addsubl
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#undef addsubw
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#undef addsubb
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#undef z_set
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#undef z_or
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#undef no_extend
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#undef extend
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#undef addop
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#undef subop
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case Operation::ADDAw:
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dest.l += u_extend16(src.w);
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break;
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case Operation::ADDAl:
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dest.l += src.l;
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break;
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case Operation::SUBAw:
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dest.l -= u_extend16(src.w);
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break;
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case Operation::SUBAl:
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dest.l -= src.l;
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break;
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case Operation::ADDAw: dest.l += u_extend16(src.w); break;
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case Operation::ADDAl: dest.l += src.l; break;
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case Operation::SUBAw: dest.l -= u_extend16(src.w); break;
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case Operation::SUBAl: dest.l -= src.l; break;
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#define get_mask() \
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const uint32_t mask_size = (instruction.mode<1>() == AddressingMode::DataRegisterDirect) ? 31 : 7; \
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@ -331,7 +268,7 @@ template <
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status.zero_result = result & 0xff;
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status.carry_flag = Status::FlagT(result & ~0xff);
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status.negative_flag = result & 0x80;
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status.overflow_flag = sub_overflow() & 0x80;
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status.overflow_flag = Primitive::overflow<false>(source, destination, uint8_t(result));
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} break;
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case Operation::CMPw: {
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@ -342,7 +279,7 @@ template <
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status.zero_result = result & 0xffff;
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status.carry_flag = Status::FlagT(result & ~0xffff);
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status.negative_flag = result & 0x8000;
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status.overflow_flag = sub_overflow() & 0x8000;
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status.overflow_flag = Primitive::overflow<false>(source, destination, uint16_t(result));
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} break;
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case Operation::CMPAw: {
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@ -353,7 +290,7 @@ template <
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status.zero_result = uint32_t(result);
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status.carry_flag = result >> 32;
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status.negative_flag = result & 0x80000000;
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status.overflow_flag = sub_overflow() & 0x80000000;
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status.overflow_flag = Primitive::overflow<false>(uint32_t(source), uint32_t(destination), uint32_t(result));
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} break;
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// TODO: is there any benefit to keeping both of these?
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@ -366,7 +303,7 @@ template <
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status.zero_result = uint32_t(result);
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status.carry_flag = result >> 32;
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status.negative_flag = result & 0x80000000;
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status.overflow_flag = sub_overflow() & 0x80000000;
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status.overflow_flag = Primitive::overflow<false>(uint32_t(source), uint32_t(destination), uint32_t(result));
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} break;
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// JMP: copies EA(0) to the program counter.
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@ -604,7 +541,7 @@ template <
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status.zero_result = result & 0xff;
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status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xff);
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status.negative_flag = result & 0x80;
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status.overflow_flag = sub_overflow() & 0x80;
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status.overflow_flag = Primitive::overflow<false>(uint8_t(source), uint8_t(destination), uint8_t(result));
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} break;
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case Operation::NEGw: {
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@ -616,7 +553,7 @@ template <
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status.zero_result = result & 0xffff;
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status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xffff);
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status.negative_flag = result & 0x8000;
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status.overflow_flag = sub_overflow() & 0x8000;
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status.overflow_flag = Primitive::overflow<false>(uint16_t(source), uint16_t(destination), uint16_t(result));
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} break;
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case Operation::NEGl: {
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@ -628,7 +565,7 @@ template <
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status.zero_result = uint_fast32_t(result);
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status.extend_flag = status.carry_flag = result >> 32;
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status.negative_flag = result & 0x80000000;
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status.overflow_flag = sub_overflow() & 0x80000000;
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status.overflow_flag = Primitive::overflow<false>(uint32_t(source), uint32_t(destination), uint32_t(result));
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} break;
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/*
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@ -643,7 +580,7 @@ template <
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status.zero_result |= result & 0xff;
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status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xff);
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status.negative_flag = result & 0x80;
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status.overflow_flag = sub_overflow() & 0x80;
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status.overflow_flag = Primitive::overflow<false>(uint8_t(source), uint8_t(destination), uint8_t(result));
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} break;
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case Operation::NEGXw: {
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@ -655,7 +592,7 @@ template <
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status.zero_result |= result & 0xffff;
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status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xffff);
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status.negative_flag = result & 0x8000;
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status.overflow_flag = sub_overflow() & 0x8000;
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status.overflow_flag = Primitive::overflow<false>(uint16_t(source), uint16_t(destination), uint16_t(result));
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} break;
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case Operation::NEGXl: {
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@ -667,7 +604,7 @@ template <
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status.zero_result |= uint_fast32_t(result);
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status.extend_flag = status.carry_flag = result >> 32;
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status.negative_flag = result & 0x80000000;
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status.overflow_flag = sub_overflow() & 0x80000000;
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status.overflow_flag = Primitive::overflow<false>(uint32_t(source), uint32_t(destination), uint32_t(result));
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} break;
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/*
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@ -1153,8 +1090,6 @@ template <
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assert(false);
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break;
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}
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#undef sub_overflow
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#undef add_overflow
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#undef u_extend16
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#undef s_extend16
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