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Implement TAS Dn, with detour for other TASes.

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This commit is contained in:
Thomas Harte 2022-05-22 16:08:30 -04:00
parent cb4d6710df
commit 1dd6ed6ae3
3 changed files with 39 additions and 3 deletions
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4
OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm
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@ -187,10 +187,10 @@ struct TestProcessor: public CPU::MC68000Mk2::BusHandler {
// @"rtr.json",
// @"rts.json",
@"swap.json",
// @"tas.json",
@"tas.json",
// @"tst.json",
]];
// _testSet = [NSSet setWithArray:@[@"PEA 0038"]];
// _testSet = [NSSet setWithArray:@[@"TAS 4ac0"]];
}
- (void)testAll {

36
Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp
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@ -165,6 +165,7 @@ enum ExecutionState: int {
MULU_MULS,
LEA,
PEA,
TAS,
};
// MARK: - The state machine.
@ -714,6 +715,20 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
MoveToStateSpecific(CalcEffectiveAddress);
});
StdCASE(TAS, {
// TAS uses a special atomic bus cycle for memory accesses,
// but is also available as DataRegisterDirect, with no
// memory access whatsoever. So segue elsewhere here only
// for the other cases.
if(instruction_.mode(0) != Mode::DataRegisterDirect) {
post_ea_state_ = TAS;
next_operand_ = 0;
MoveToStateSpecific(CalcEffectiveAddress);
}
perform_state_ = Perform_np;
});
default:
assert(false);
}
@ -1902,6 +1917,17 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
Prefetch();
MoveToStateSpecific(Decode);
//
// TAS
//
BeginState(TAS):
// TODO: use the specialised TAS bus cycle; five parts.
// PerformBusOperation
Prefetch();
MoveToStateSpecific(Decode);
//
// Various states TODO.
//
@ -2019,6 +2045,16 @@ template <bool use_current_instruction_pc> void ProcessorBase::raise_exception(i
exception_vector_ = vector;
}
inline void ProcessorBase::tas(Preinstruction instruction, uint32_t) {
// This will be reached only if addressing mode is Dn.
const uint8_t value = registers_[instruction.reg(0)].b;
registers_[instruction.reg(0)].b |= 0x80;
status_.overflow_flag = status_.carry_flag = 0;
status_.zero_result = value;
status_.negative_flag = value & 0x80;
}
// MARK: - External state.
template <class BusHandler, bool dtack_is_implicit, bool permit_overrun, bool signal_will_perform>

2
Processors/68000Mk2/Implementation/68000Mk2Storage.hpp
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@ -143,7 +143,7 @@ struct ProcessorBase: public InstructionSet::M68k::NullFlowController {
inline void unlink(uint32_t &) {} //
inline void move_to_usp(uint32_t) {} //
inline void move_from_usp(uint32_t &) {} //
inline void tas(Preinstruction, uint32_t) {} //
inline void tas(Preinstruction, uint32_t);
template <bool use_current_instruction_pc = true> void raise_exception(int);
// These aren't implemented because the specific details of the implementation