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Completes M50740 instruction set.

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This commit is contained in:
Thomas Harte 2021-01-21 19:08:38 -05:00
parent 3c887aff95
commit 0fafbf5092
3 changed files with 25 additions and 4 deletions
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7
InstructionSets/CachingExecutor.hpp
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@ -118,6 +118,13 @@ template <
// }
}
/*!
Indicates whether the processor is currently 'stopped', i.e. whether all attempts to run
should produce no activity. Some processors have such a state when waiting for
interrupts or for a reset.
*/
void set_is_stopped(bool) {}
/*!
Executes up to the next branch.
*/

21
InstructionSets/M50740/Executor.cpp
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@ -116,6 +116,15 @@ uint8_t Executor::flags() {
carry_flag_;
}
template<bool is_brk> inline void Executor::perform_interrupt() {
// BRK has an unused operand.
++program_counter_;
push(uint8_t(program_counter_ >> 8));
push(uint8_t(program_counter_ & 0xff));
push(flags() | (is_brk ? 0x10 : 0x00));
set_program_counter(uint16_t(memory_[0x1ff4] | (memory_[0x1ff5] << 8)));
}
template <Operation operation, AddressingMode addressing_mode> void Executor::perform() {
// Deal with all modes that don't access memory up here;
// those that access memory will go through a slightly longer
@ -336,6 +345,14 @@ template <Operation operation> void Executor::perform(uint8_t *operand [[maybe_u
// after exiting from here.
} break;
case Operation::BRK:
perform_interrupt<true>();
--program_counter_; // To undo the unavoidable increment
// after exiting from here.
break;
case Operation::STP: set_is_stopped(true); break;
case Operation::COM: set_nz(*operand ^= 0xff); break;
case Operation::FST: case Operation::SLW: case Operation::NOP:
@ -347,10 +364,6 @@ template <Operation operation> void Executor::perform(uint8_t *operand [[maybe_u
case Operation::PLA: set_nz(a_ = pull()); break;
case Operation::PLP: set_flags(pull()); break;
// TODO:
//
// BRK, STP
case Operation::ASL:
carry_flag_ = *operand >> 7;
*operand <<= 1;

1
InstructionSets/M50740/Executor.hpp
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@ -132,6 +132,7 @@ class Executor: public CachingExecutor {
inline uint8_t pull();
inline void set_flags(uint8_t);
inline uint8_t flags();
template<bool is_brk> inline void perform_interrupt();
};
}