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STA (without tests)

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jborza 2019-04-16 00:09:55 +02:00
parent 891bb328a4
commit 86dd2eaf99
1 changed files with 24 additions and 11 deletions
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35
cpu.c
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@ -77,6 +77,10 @@ void LDY(State6502 * state, byte operand) {
set_NV_flags(state, state->y);
}
void STA(State6502 * state, word address) {
state->memory[address] = state->a;
}
void STX(State6502 * state, word address) {
state->memory[address] = state->x;
}
@ -173,22 +177,31 @@ byte get_byte_absolute_y(State6502 * state) {
return state->memory[get_address_absolute_y(state)];
}
byte get_byte_indirect_x(State6502 * state) {
word get_address_indirect_x(State6502 * state) {
//pre-indexed indirect with the X register
//zero-page address is added to x register
byte indirect_address = pop_byte(state) + state->x;
//pointing to address of a word holding the address of the operand
word address = read_word(state, indirect_address);
return state->memory[address];
return address;
}
byte get_byte_indirect_y(State6502 * state) {
byte get_byte_indirect_x(State6502 * state) {
//pre-indexed indirect with the X register
return state->memory[get_address_indirect_x(state)];
}
word get_address_indirect_y(State6502 * state) {
//post-indexed indirect
//zero-page address as an argument
byte indirect_address = pop_byte(state);
//the address and the following byte is read as a word, adding Y register
word address = read_word(state, indirect_address) + state->y;
return state->memory[address];
return address;
}
byte get_byte_indirect_y(State6502 * state) {
return state->memory[get_address_indirect_y(state)];
}
int emulate_6502_op(State6502 * state) {
@ -338,13 +351,13 @@ int emulate_6502_op(State6502 * state) {
case SBC_ABSY: unimplemented_instruction(state); break;
case SBC_INDX: unimplemented_instruction(state); break;
case SBC_INDY: unimplemented_instruction(state); break;
case STA_ZP: unimplemented_instruction(state); break;
case STA_ZPX: unimplemented_instruction(state); break;
case STA_ABS: unimplemented_instruction(state); break;
case STA_ABSX: unimplemented_instruction(state); break;
case STA_ABSY: unimplemented_instruction(state); break;
case STA_INDX: unimplemented_instruction(state); break;
case STA_INDY: unimplemented_instruction(state); break;
case STA_ZP: STA(state, get_address_zero_page(state)); break;
case STA_ZPX: STA(state, get_address_zero_page_x(state)); break;
case STA_ABS: STA(state, get_address_absolute(state)); break;
case STA_ABSX: STA(state, get_address_absolute_x(state)); break;
case STA_ABSY: STA(state, get_address_absolute_y(state)); break;
case STA_INDX: STA(state, get_address_indirect_x(state)); break;
case STA_INDY: STA(state, get_address_indirect_y(state)); break;
case STX_ZP: STX(state, get_address_zero_page(state)); break;
case STX_ZPY: STX(state, get_address_zero_page_y(state)); break;
case STX_ABS: STX(state, get_address_absolute(state)); break;