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implemented TAX,TXA,TAY,TYA, DEX, DEY, INX, INY

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This commit is contained in:
jborza 2019-04-14 23:40:53 +02:00
parent c034141ee5
commit c8824992c6
1 changed files with 31 additions and 23 deletions
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54
cpu.c
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@ -11,20 +11,28 @@ void* unimplemented_instruction(State6502* state) {
}
void set_NV_flags(State6502* state, byte value) {
//TODO implement V flag
//N flag
state->flags.n = ((1 << 7) & value) != 0;
//TODO implement NV flags
}
void set_NZ_flags(State6502 * state, byte value) {
//Z flag
if (value) {
state->flags.z = 0;
}
else {
state->flags.z = 1;
}
//N flag
state->flags.n = ((1 << 7) & value) != 0;
}
void clear_flags(State6502* state) {
void clear_flags(State6502 * state) {
memcpy(&state->flags, &state->a, 1);
}
void clear_state(State6502* state) {
void clear_state(State6502 * state) {
state->a = 0;
state->x = 0;
state->y = 0;
@ -34,49 +42,49 @@ void clear_state(State6502* state) {
state->running = 1;
}
byte pop_byte(State6502* state) {
byte pop_byte(State6502 * state) {
return state->memory[state->pc++];
}
//bitwise or with accumulator
void ORA(State6502* state, byte operand) {
void ORA(State6502 * state, byte operand) {
byte result = state->a | operand;
set_NV_flags(state, result);
state->a = result;
}
//bitwise and with accumulator
void AND(State6502* state, byte operand) {
void AND(State6502 * state, byte operand) {
byte result = state->a & operand;
set_NV_flags(state, result);
state->a = result;
}
//load accumulator
void LDA(State6502* state, byte operand) {
void LDA(State6502 * state, byte operand) {
state->a = operand;
set_NV_flags(state, state->a);
}
void LDX(State6502* state, byte operand) {
void LDX(State6502 * state, byte operand) {
state->x = operand;
set_NV_flags(state, state->x);
}
void LDY(State6502* state, byte operand) {
void LDY(State6502 * state, byte operand) {
state->y = operand;
set_NV_flags(state, state->y);
}
void STX(State6502* state, word address) {
void STX(State6502 * state, word address) {
state->memory[address] = state->x;
}
void STY(State6502* state, word address) {
void STY(State6502 * state, word address) {
state->memory[address] = state->y;
}
word pop_word(State6502* state) {
word pop_word(State6502 * state) {
byte low = pop_byte(state);
byte high = pop_byte(state);
word result = (high << 8) | low;
@ -87,7 +95,7 @@ word read_word(State6502 * state, word address) {
return state->memory[address] | state->memory[address + 1] << 8;
}
word get_address_zero_page(State6502* state) {
word get_address_zero_page(State6502 * state) {
return pop_byte(state);
}
@ -97,7 +105,7 @@ byte get_byte_zero_page(State6502 * state) {
return state->memory[address];
}
word get_address_zero_page_x(State6502* state) {
word get_address_zero_page_x(State6502 * state) {
//address is zero page, so wraparound byte
byte address = pop_byte(state) + state->x;
return address;
@ -108,7 +116,7 @@ byte get_byte_zero_page_x(State6502 * state) {
return state->memory[address];
}
word get_address_zero_page_y(State6502* state) {
word get_address_zero_page_y(State6502 * state) {
//address is zero page, so wraparound byte
byte address = pop_byte(state) + state->y;
return address;
@ -215,10 +223,10 @@ int emulate_6502_op(State6502 * state) {
case SEC: unimplemented_instruction(state); break;
case SED: unimplemented_instruction(state); break;
case SEI: unimplemented_instruction(state); break;
case TAX: unimplemented_instruction(state); break;
case TXA: unimplemented_instruction(state); break;
case TAY: unimplemented_instruction(state); break;
case TYA: unimplemented_instruction(state); break;
case TAX: state->x = state->a; set_NZ_flags(state, state->x); break; //TODO test
case TXA: state->a = state->x; set_NZ_flags(state, state->a); break; //TODO test
case TAY: state->y = state->a; set_NZ_flags(state, state->y); break; //TODO test
case TYA: state->a = state->y; set_NZ_flags(state, state->a); break; //TODO test
case TSX: unimplemented_instruction(state); break;
case TXS: unimplemented_instruction(state); break;
case CMP_IMM: unimplemented_instruction(state); break;
@ -239,10 +247,10 @@ int emulate_6502_op(State6502 * state) {
case DEC_ZPX: unimplemented_instruction(state); break;
case DEC_ABS: unimplemented_instruction(state); break;
case DEC_ABSX: unimplemented_instruction(state); break;
case DEX: unimplemented_instruction(state); break;
case DEY: unimplemented_instruction(state); break;
case INX: unimplemented_instruction(state); break;
case INY: unimplemented_instruction(state); break;
case DEX: state->x -= 1; set_NZ_flags(state, state->x); break;
case DEY: state->y -= 1; set_NZ_flags(state, state->y); break;
case INX: state->x += 1; set_NZ_flags(state, state->x); break;
case INY: state->y += 1; set_NZ_flags(state, state->y); break;
case EOR_IMM: unimplemented_instruction(state); break;
case EOR_ZP: unimplemented_instruction(state); break;
case EOR_ZPX: unimplemented_instruction(state); break;