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Takes a swing at BBC, BBS.

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This commit is contained in:
Thomas Harte 2021-01-20 20:52:04 -05:00
parent 4f02e8fbaf
commit cf8afc70b2
1 changed files with 23 additions and 10 deletions
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33
InstructionSets/M50740/Executor.cpp
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@ -163,13 +163,29 @@ template <Operation operation, AddressingMode addressing_mode> void Executor::pe
program_counter_ += 1 + size(addressing_mode);
return;
/* TODO:
AccumulatorRelative
ZeroPageRelative
... which are BBC/BBS-exclusive.
*/
case AddressingMode::AccumulatorRelative:
case AddressingMode::ZeroPageRelative: {
// Order of bytes is: (i) zero page address; (ii) relative jump.
uint8_t value;
if constexpr (addressing_mode == AddressingMode::AccumulatorRelative) {
value = a_;
address = program_counter_ + 1 + size(addressing_mode) + int8_t(next8());
} else {
value = read(next8());
address = program_counter_ + 1 + size(addressing_mode) + int8_t(memory_[(program_counter_+2)&0x1fff]);
}
program_counter_ += 1 + size(addressing_mode);
switch(operation) {
case Operation::BBS0: case Operation::BBS1: case Operation::BBS2: case Operation::BBS3:
case Operation::BBS4: case Operation::BBS5: case Operation::BBS6: case Operation::BBS7:
if(value & (1 << (int(operation) - int(Operation::BBS0)))) set_program_counter(uint16_t(address));
return;
case Operation::BBC0: case Operation::BBC1: case Operation::BBC2: case Operation::BBC3:
case Operation::BBC4: case Operation::BBC5: case Operation::BBC6: case Operation::BBC7:
if(value & (1 << (int(operation) - int(Operation::BBC0)))) set_program_counter(uint16_t(address));
return;
}
} break;
// Addressing modes with a memory access.
@ -229,12 +245,9 @@ template <Operation operation, AddressingMode addressing_mode> void Executor::pe
case Operation::BVS: if(overflow_result_ & 0x80) set_program_counter(uint16_t(address)); return;
case Operation::BVC: if(!(overflow_result_ & 0x80)) set_program_counter(uint16_t(address)); return;
/* TODO: BBC, BBS. */
default: break;
}
assert(access_type(operation) != AccessType::None);
if constexpr(access_type(operation) == AccessType::Read) {