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Collapse MOVE and NEG[X] similarities.

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This commit is contained in:
Thomas Harte 2022-10-11 21:27:18 -04:00
parent 1f19141746
commit eff9a09b9f
1 changed files with 31 additions and 87 deletions
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118
InstructionSets/M68k/Implementation/PerformImplementation.hpp
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@ -212,6 +212,28 @@ void divide(uint16_t source, uint32_t &destination, Status &status, FlowControll
did_divide<is_divu, false>(dividend, divisor, flow_controller);
}
template <typename IntT> void move(IntT source, IntT &destination, Status &status) {
destination = source;
status.zero_result = Status::FlagT(source);
status.negative_flag = status.zero_result & top_bit<IntT>();
status.overflow_flag = status.carry_flag = 0;
}
template <bool is_extend, typename IntT> void negative(IntT &source, Status &status) {
const IntT result = -source - (is_extend && status.extend_flag ? 1 : 0);
if constexpr (is_extend) {
status.zero_result |= result;
} else {
status.zero_result = result;
}
status.extend_flag = status.carry_flag = result; // i.e. any value other than 0 will result in carry.
status.negative_flag = result & top_bit<IntT>();
status.overflow_flag = Primitive::overflow<false>(source, IntT(0), result);
source = result;
}
}
template <
@ -363,23 +385,9 @@ template <
MOVE.b, MOVE.l and MOVE.w: move the least significant byte or word, or the entire long word,
and set negative, zero, overflow and carry as appropriate.
*/
case Operation::MOVEb:
status.zero_result = dest.b = src.b;
status.negative_flag = status.zero_result & 0x80;
status.overflow_flag = status.carry_flag = 0;
break;
case Operation::MOVEw:
status.zero_result = dest.w = src.w;
status.negative_flag = status.zero_result & 0x8000;
status.overflow_flag = status.carry_flag = 0;
break;
case Operation::MOVEl:
status.zero_result = dest.l = src.l;
status.negative_flag = status.zero_result & 0x80000000;
status.overflow_flag = status.carry_flag = 0;
break;
case Operation::MOVEb: Primitive::move(src.b, dest.b, status); break;
case Operation::MOVEw: Primitive::move(src.w, dest.w, status); break;
case Operation::MOVEl: Primitive::move(src.l, dest.l, status); break;
/*
MOVEA.l: move the entire long word;
@ -503,80 +511,16 @@ template <
and SUB calculates `destination - source`, the NEGs deliberately
label 'source' and 'destination' differently from Motorola.
*/
case Operation::NEGb: {
const int destination = 0;
const int source = src.b;
const auto result = destination - source;
src.b = uint8_t(result);
status.zero_result = result & 0xff;
status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xff);
status.negative_flag = result & 0x80;
status.overflow_flag = Primitive::overflow<false>(uint8_t(source), uint8_t(destination), uint8_t(result));
} break;
case Operation::NEGw: {
const int destination = 0;
const int source = src.w;
const auto result = destination - source;
src.w = uint16_t(result);
status.zero_result = result & 0xffff;
status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xffff);
status.negative_flag = result & 0x8000;
status.overflow_flag = Primitive::overflow<false>(uint16_t(source), uint16_t(destination), uint16_t(result));
} break;
case Operation::NEGl: {
const uint64_t destination = 0;
const uint64_t source = src.l;
const auto result = destination - source;
src.l = uint32_t(result);
status.zero_result = uint_fast32_t(result);
status.extend_flag = status.carry_flag = result >> 32;
status.negative_flag = result & 0x80000000;
status.overflow_flag = Primitive::overflow<false>(uint32_t(source), uint32_t(destination), uint32_t(result));
} break;
case Operation::NEGb: Primitive::negative<false>(src.b, status); break;
case Operation::NEGw: Primitive::negative<false>(src.w, status); break;
case Operation::NEGl: Primitive::negative<false>(src.l, status); break;
/*
NEGXs: NEG, with extend.
*/
case Operation::NEGXb: {
const int source = src.b;
const int destination = 0;
const auto result = destination - source - (status.extend_flag ? 1 : 0);
src.b = uint8_t(result);
status.zero_result |= result & 0xff;
status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xff);
status.negative_flag = result & 0x80;
status.overflow_flag = Primitive::overflow<false>(uint8_t(source), uint8_t(destination), uint8_t(result));
} break;
case Operation::NEGXw: {
const int source = src.w;
const int destination = 0;
const auto result = destination - source - (status.extend_flag ? 1 : 0);
src.w = uint16_t(result);
status.zero_result |= result & 0xffff;
status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xffff);
status.negative_flag = result & 0x8000;
status.overflow_flag = Primitive::overflow<false>(uint16_t(source), uint16_t(destination), uint16_t(result));
} break;
case Operation::NEGXl: {
const uint64_t source = src.l;
const uint64_t destination = 0;
const auto result = destination - source - (status.extend_flag ? 1 : 0);
src.l = uint32_t(result);
status.zero_result |= uint_fast32_t(result);
status.extend_flag = status.carry_flag = result >> 32;
status.negative_flag = result & 0x80000000;
status.overflow_flag = Primitive::overflow<false>(uint32_t(source), uint32_t(destination), uint32_t(result));
} break;
case Operation::NEGXb: Primitive::negative<true>(src.b, status); break;
case Operation::NEGXw: Primitive::negative<true>(src.w, status); break;
case Operation::NEGXl: Primitive::negative<true>(src.l, status); break;
/*
The no-op.