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Corrects various flag issues with ADD, SUB and NEG.

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This commit is contained in:
Thomas Harte 2019-04-25 13:53:23 -04:00
parent 5725db9234
commit 723acb31b3
1 changed files with 33 additions and 29 deletions
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62
Processors/68000/Implementation/68000Implementation.hpp
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@ -94,8 +94,8 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
case int(MicroOp::Action::None): break;
case int(MicroOp::Action::PerformOperation):
#define sub_overflow() (source ^ destination) & (destination ^ result)
#define add_overflow() ~(source ^ destination) & (destination ^ result)
#define sub_overflow() ((result ^ destination) & (destination ^ source))
#define add_overflow() ((result ^ destination) & ~(destination ^ source))
switch(active_program_->operation) {
/*
ABCD adds the lowest bytes form the source and destination using BCD arithmetic,
@ -128,9 +128,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
#define subop(a, b) a - b
#define addsubb(a, b, dest, op, overflow) \
const auto source = a; \
const auto destination = b; \
const int result = op(destination, source); \
const int source = a; \
const int destination = b; \
const auto result = op(destination, source); \
\
zero_result_ = dest = uint8_t(result); \
extend_flag_ = carry_flag_ = result & ~0xff; \
@ -138,9 +138,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
overflow_flag_ = overflow() & 0x80;
#define addsubw(a, b, dest, op, overflow) \
const auto source = a; \
const auto destination = b; \
const int result = op(destination, source); \
const int source = a; \
const int destination = b; \
const auto result = op(destination, source); \
\
zero_result_ = dest = uint16_t(result); \
extend_flag_ = carry_flag_ = result & ~0xffff; \
@ -148,9 +148,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
overflow_flag_ = overflow() & 0x8000;
#define addsubl(a, b, dest, op, overflow) \
const auto source = a; \
const auto destination = b; \
const uint64_t result = op(uint64_t(destination), uint64_t(source)); \
const uint64_t source = a; \
const uint64_t destination = b; \
const auto result = op(destination, source); \
\
zero_result_ = dest = uint32_t(result); \
extend_flag_ = carry_flag_ = result >> 32; \
@ -767,11 +767,15 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
/*
NEGs: negatives the destination, setting the zero,
negative, overflow and carry flags appropriate, and extend.
NB: since the same logic as SUB is used to calculate overflow,
and SUB calculates `destination - source`, the NEGs deliberately
label 'source' and 'destination' differently from Motorola.
*/
case Operation::NEGb: {
const int source = 0;
const int destination = active_program_->destination->halves.low.halves.low;
const int result = source - destination;
const int destination = 0;
const int source = active_program_->destination->halves.low.halves.low;
const auto result = destination - source;
active_program_->destination->halves.low.halves.low = result;
zero_result_ = result & 0xff;
@ -781,9 +785,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
} break;
case Operation::NEGw: {
const int source = 0;
const int destination = active_program_->destination->halves.low.full;
const int result = source - destination;
const int destination = 0;
const int source = active_program_->destination->halves.low.full;
const auto result = destination - source;
active_program_->destination->halves.low.full = result;
zero_result_ = result & 0xffff;
@ -793,9 +797,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
} break;
case Operation::NEGl: {
const int source = 0;
const int destination = active_program_->destination->full;
int64_t result = source - destination;
const uint64_t destination = 0;
const uint64_t source = active_program_->destination->full;
const auto result = destination - source;
active_program_->destination->full = uint32_t(result);
zero_result_ = uint_fast32_t(result);
@ -808,9 +812,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
NEGXs: NEG, with extend.
*/
case Operation::NEGXb: {
const int source = 0;
const int destination = active_program_->destination->halves.low.halves.low;
const int result = source - destination - (extend_flag_ ? 1 : 0);
const int source = active_program_->destination->halves.low.halves.low;
const int destination = 0;
const auto result = destination - source - (extend_flag_ ? 1 : 0);
active_program_->destination->halves.low.halves.low = result;
zero_result_ = result & 0xff;
@ -820,9 +824,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
} break;
case Operation::NEGXw: {
const int source = 0;
const int destination = active_program_->destination->halves.low.full;
const int result = source - destination - (extend_flag_ ? 1 : 0);
const int source = active_program_->destination->halves.low.full;
const int destination = 0;
const auto result = destination - source - (extend_flag_ ? 1 : 0);
active_program_->destination->halves.low.full = result;
zero_result_ = result & 0xffff;
@ -832,9 +836,9 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
} break;
case Operation::NEGXl: {
const int source = 0;
const int destination = active_program_->destination->full;
int64_t result = source - destination - (extend_flag_ ? 1 : 0);
const uint64_t source = active_program_->destination->full;
const uint64_t destination = 0;
const auto result = destination - source - (extend_flag_ ? 1 : 0);
active_program_->destination->full = uint32_t(result);
zero_result_ = uint_fast32_t(result);