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refactored PHP, PLP, PLA

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jborza 2019-04-27 13:18:28 +02:00
parent 4ad8a47739
commit 8b841b3227
1 changed files with 28 additions and 13 deletions
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41
cpu.c
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@ -279,6 +279,14 @@ void RTS_(State6502* state) {
state->pc = address + 1;
}
void RTI_(State6502* state) {
//interrupt pushes PC first, then status register
//RTI should pull status register and program counter from the stack
byte sr = pop_byte_from_stack(state);
word address = pop_word_from_stack(state);
state->pc = address;
}
void BEQ(State6502* state) {
word address = get_address_relative(state);
if (state->flags.z)
@ -327,6 +335,22 @@ void BVC(State6502* state) {
state->pc = address;
}
void PLA_(State6502* state) {
state->a = pop_byte_from_stack(state);
set_NZ_flags(state, state->a);
}
void PLP_(State6502* state) {
byte value = pop_byte_from_stack(state);
memset(&state->flags, value, sizeof(Flags));
}
void PHP_(State6502* state) {
byte flags_value;
memcpy(&flags_value, &state->flags, sizeof(Flags));
push_byte_to_stack(state, flags_value);
}
word pop_word(State6502 * state) {
byte low = pop_byte(state);
byte high = pop_byte(state);
@ -377,19 +401,10 @@ int emulate_6502_op(State6502 * state) {
case CLV: state->flags.v = 0; break;
case NOP: break; //NOP
case PHA: push_byte_to_stack(state, state->a); break; //push accumulator to stack
case PLA: state->a = pop_byte_from_stack(state); break; //pull accumulator from stack
case PHP: {
byte flags_value;
memcpy(&flags_value, &state->flags, sizeof(Flags));
push_byte_to_stack(state, flags_value);
break; //push processor status
}
case PLP: {
byte value = pop_byte_from_stack(state);
memset(&state->flags, value, 1);
break;
}//pull procesor status
case RTI: unimplemented_instruction(state); break;
case PLA: PLA_(state); break; //pull accumulator from stack
case PHP: PHP_(state); break; //push processor status
case PLP: PLP_(state); break; //pull procesor status
case RTI: RTI_(state); break;
case RTS: RTS_(state); break;
case SEC: state->flags.c = 1; break;
case SED: state->flags.d = 1; break;