6502/emu6502
1
0
Fork 0
mirror of https://github.com/jborza/emu6502.git synced 2024-06-08 22:29:41 +00:00
Code Issues Projects Releases Wiki Activity

refactored PHP, PLP, PLA

Browse Source
This commit is contained in:
jborza 2019-04-27 13:18:28 +02:00
parent 4ad8a47739
commit 8b841b3227
1 changed files with 28 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
cpu.c
View File

@ -279,6 +279,14 @@ void RTS_(State6502* state) {
state->pc = address + 1; 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) { void BEQ(State6502* state) {
word address = get_address_relative(state); word address = get_address_relative(state);
if (state->flags.z) if (state->flags.z)
@ -327,6 +335,22 @@ void BVC(State6502* state) {
state->pc = address; 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) { word pop_word(State6502 * state) {
byte low = pop_byte(state); byte low = pop_byte(state);
byte high = 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 CLV: state->flags.v = 0; break;
case NOP: break; //NOP case NOP: break; //NOP
case PHA: push_byte_to_stack(state, state->a); break; //push accumulator to stack 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 PLA: PLA_(state); break; //pull accumulator from stack
case PHP: { case PHP: PHP_(state); break; //push processor status
byte flags_value; case PLP: PLP_(state); break; //pull procesor status
memcpy(&flags_value, &state->flags, sizeof(Flags)); case RTI: RTI_(state); break;
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 RTS: RTS_(state); break; case RTS: RTS_(state); break;
case SEC: state->flags.c = 1; break; case SEC: state->flags.c = 1; break;
case SED: state->flags.d = 1; break; case SED: state->flags.d = 1; break;