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Commute ROXL and ROXR into a template.

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This commit is contained in:
Thomas Harte 2022-10-16 12:06:28 -04:00
parent 0a9c392371
commit fee072b404
1 changed files with 60 additions and 35 deletions
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95
InstructionSets/M68k/Implementation/PerformImplementation.hpp
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@ -235,6 +235,59 @@ template <typename IntT> void test(IntT source, Status &status) {
status.negative_flag = status.zero_result & top_bit<IntT>();
}
template <typename IntT, typename FlowController> int shift_count(uint8_t source, FlowController &flow_controller) {
const int count = source & 63;
flow_controller.template did_shift<IntT>(count);
return count;
}
/// @returns The number of bits in @c IntT.
template <typename IntT> constexpr int bit_size() {
return sizeof(IntT) * 8;
}
template <typename IntT> void set_neg_zero(IntT result, Status &status) {
status.zero_result = Status::FlagT(result);
status.negative_flag = result & top_bit<IntT>();
}
template <typename IntT> void set_neg_zero_overflow(IntT result, IntT destination, Status &status) {
set_neg_zero<IntT>(result, status);
status.overflow_flag = Status::FlagT((destination ^ result) & top_bit<IntT>());
}
/// Perform a rotate-through-extend, i.e. any of ROX[L/R].[b/w/l].
template <Operation operation, typename IntT, typename FlowController> void rox(uint32_t source, IntT &destination, Status &status, FlowController &flow_controller) {
static_assert(
operation == Operation::ROXLb || operation == Operation::ROXLw || operation == Operation::ROXLl ||
operation == Operation::ROXRb || operation == Operation::ROXRw || operation == Operation::ROXRl
);
const auto size = bit_size<IntT>();
const auto shift = shift_count<IntT>(uint8_t(source), flow_controller) % (size + 1);
uint64_t compound =
uint64_t(destination) |
(status.extend_flag ? (1ull << size) : 0);
switch(operation) {
case Operation::ROXLb: case Operation::ROXLw: case Operation::ROXLl:
compound =
(compound << shift) |
(compound >> (size + 1 - shift));
break;
case Operation::ROXRb: case Operation::ROXRw: case Operation::ROXRl:
compound =
(compound >> shift) |
(compound << (size + 1 - shift));
break;
}
status.carry_flag = status.extend_flag = Status::FlagT((compound >> size) & 1);
set_neg_zero_overflow(IntT(compound), destination, status);
destination = IntT(compound);
}
}
template <
@ -865,19 +918,7 @@ template <
case Operation::RORw: ror(dest.w, 16); break;
case Operation::RORl: ror(dest.l, 32); break;
#define roxl(destination, size) { \
decode_shift_count(decltype(destination)); \
\
shift_count %= (size + 1); \
uint64_t compound = uint64_t(destination) | (status.extend_flag ? (1ull << size) : 0); \
compound = \
(compound << shift_count) | \
(compound >> (size + 1 - shift_count)); \
status.carry_flag = status.extend_flag = Status::FlagT((compound >> size) & 1); \
destination = decltype(destination)(compound); \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
// ---
case Operation::ROXLm: {
const auto value = src.w;
@ -885,23 +926,9 @@ template <
status.extend_flag = value & 0x8000;
set_flags_w(0x8000);
} break;
case Operation::ROXLb: roxl(dest.b, 8); break;
case Operation::ROXLw: roxl(dest.w, 16); break;
case Operation::ROXLl: roxl(dest.l, 32); break;
#define roxr(destination, size) { \
decode_shift_count(decltype(destination)); \
\
shift_count %= (size + 1); \
uint64_t compound = uint64_t(destination) | (status.extend_flag ? (1ull << size) : 0); \
compound = \
(compound >> shift_count) | \
(compound << (size + 1 - shift_count)); \
status.carry_flag = status.extend_flag = Status::FlagT((compound >> size) & 1); \
destination = decltype(destination)(compound); \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ROXLb: Primitive::rox<Operation::ROXLb>(src.l, dest.b, status, flow_controller); break;
case Operation::ROXLw: Primitive::rox<Operation::ROXLw>(src.l, dest.w, status, flow_controller); break;
case Operation::ROXLl: Primitive::rox<Operation::ROXLl>(src.l, dest.l, status, flow_controller); break;
case Operation::ROXRm: {
const auto value = src.w;
@ -909,12 +936,10 @@ template <
status.extend_flag = value & 0x0001;
set_flags_w(0x0001);
} break;
case Operation::ROXRb: roxr(dest.b, 8); break;
case Operation::ROXRw: roxr(dest.w, 16); break;
case Operation::ROXRl: roxr(dest.l, 32); break;
case Operation::ROXRb: Primitive::rox<Operation::ROXRb>(src.l, dest.b, status, flow_controller); break;
case Operation::ROXRw: Primitive::rox<Operation::ROXRw>(src.l, dest.w, status, flow_controller); break;
case Operation::ROXRl: Primitive::rox<Operation::ROXRl>(src.l, dest.l, status, flow_controller); break;
#undef roxr
#undef roxl
#undef ror
#undef rol
#undef asr