811 lines
16 KiB
C++
811 lines
16 KiB
C++
#include "stdafx.h"
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#include <iostream>
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#include "memory.h"
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#include "CPU.h"
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#include "state.h"
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#define PN FLAG_SIGN
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#define PV FLAG_OVERFLOW
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#define PB FLAG_BREAKPOINT
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#define PD FLAG_DECIMAL
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#define PI FLAG_INTERRUPT
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#define PZ FLAG_ZERO
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#define PC FLAG_CARRY
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unsigned char hex2bcd(unsigned char x)
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{
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unsigned char y;
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y = (x / 10) << 4;
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y = y | (x % 10);
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return (y);
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}
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/* These functions require the complete and pre-calculated address to function properly.
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If there is no parameter on the function, it's either implied or accumulator.
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Assume that PC value is correct coming in.
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When branching because we don't know if we were successful until now
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so we need to add +1 to cycles on a successful branch and another +1 if the branch
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goes to a different page.
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crossedPageBoundary tells us if we need to increase cycle count by 1 if we crossed the page boundary
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CPU::lastInstructionCrossedPageBoundary keeps track of if we did or not
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if both are true, increase cycle count by 1.
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*/
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void CPU::op_adc(WideAddress address, bool crossedPageBoundary) {
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/*
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Logic:
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t = A + M + P.C
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P.V = (A.7!=t.7) ? 1:0
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P.N = A.7
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P.Z = (t==0) ? 1:0
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IF (P.D)
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t = bcd(A) + bcd(M) + P.C
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P.C = (t>99) ? 1:0
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ELSE
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P.C = (t>255) ? 1:0
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A = t & 0xFF
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*/
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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if (accumulator == 0x7f) {
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int x = 0;
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}
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uint16_t t = accumulator + fetch_memory_byte(address, false) + FLAG_CARRY;
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int8_t t8 = t & 0xff;
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PV = (~(accumulator ^ fetch_memory_byte(address, false)) & (accumulator ^ t8) & 0x80) == 0x80;
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PZ = (t8 == 0);
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PN = (t8 & 0x80) == 0x80;
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if (PD) {
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t = hex2bcd(accumulator) + hex2bcd(fetch_memory_byte(address, false)) + PC;
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PC = (t > 99);
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}
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else {
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PC = (t > 255);
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}
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accumulator = (t & 0xFF);
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};
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void CPU::op_adc(uint8_t immediate, bool crossedPageBoundary) {
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/*
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Logic:
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t = A + M + P.C
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P.V = (A.7 != t.7) ? 1:0
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P.N = A.7
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P.Z = (t==0) ? 1:0
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IF (P.D)
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t = bcd(A) + bcd(M) + P.C
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P.C = (t>99) ? 1:0
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ELSE
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P.C = (t>255) ? 1:0
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A = t & 0xFF
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*/
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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if (accumulator == 0x7f) {
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int x = 0;
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}
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uint16_t t = accumulator + immediate + FLAG_CARRY;
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int8_t t8 = t & 0xff;
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/*/
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if ((accumulator & 0x80) != (t & 0x80)) {
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PV = true;
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}
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else {
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PV = false;
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}
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*/
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PV = (~(accumulator ^ immediate) & (accumulator ^ t) & 0x80) == 0x80;
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PN = (t8 & 0x80) == 0x80;
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PZ = (t8 == 0);
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//TODO: FLAG_DECIMAL
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if (PD) {
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t = hex2bcd(accumulator) + hex2bcd(immediate) + PC;
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PC = (t > 99);
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}
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else {
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PC = (t > 255);
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}
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accumulator = (t & 0xFF);
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};
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void CPU::op_and(WideAddress address, bool crossedPageBoundary) {
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/*
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Logic:
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A = A & M
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P.N = A.7
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P.Z = (A==0) ? 1:0 */
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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accumulator = (accumulator & fetch_memory_byte(address, false));
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FLAG_SIGN = (accumulator & 0x80) == 0x80;
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FLAG_ZERO = (accumulator == 0);
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}
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void CPU::op_and(uint8_t immediate, bool crossedPageBoundary) {
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/*
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Logic:
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A = A & M
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P.N = A.7
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P.Z = (A==0) ? 1:0 */
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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accumulator = (accumulator & immediate);
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FLAG_SIGN = (accumulator & 0x80) == 0x80;
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FLAG_ZERO = (accumulator == 0);
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}
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void CPU::op_asl(WideAddress address) { //OK
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/*
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Logic:
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P.C = B.7
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B = (B << 1) & $FE
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P.N = B.7
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P.Z = (B==0) ? 1:0
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*/
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FLAG_CARRY = (fetch_memory_byte(address, false) & 0x80) == 0x80;
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write_memory_byte(address, (fetch_memory_byte(address, false) << 1) & 0xFE);
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FLAG_SIGN = (fetch_memory_byte(address, false) & 0x80) == 0x80;
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FLAG_ZERO = (fetch_memory_byte(address, false) == 0);
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}
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void CPU::op_asl() {
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/*
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Logic:
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P.C = B.7
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B = (B << 1) & $FE
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P.N = B.7
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P.Z = (B==0) ? 1:0
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*/
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FLAG_CARRY = (accumulator & 0x80) == 0x80;
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accumulator = (accumulator << 1) & 0xFE;
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FLAG_SIGN = (accumulator & 0x80) == 0x80;
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FLAG_ZERO = (accumulator == 0);
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}
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void CPU::op_bcc(int8_t relative) {
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if (!FLAG_CARRY) {
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//+1 cycle for branching, +2 if branching to a different page
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if ((program_counter & 0x00FF) + relative > 0x100) {
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cycles++;
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}
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cycles++;
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program_counter += relative;
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}
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}
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void CPU::op_bcs(int8_t relative) {
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if (FLAG_CARRY) {
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//+1 cycle for branching, +2 if branching to a different page
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if ((program_counter & 0x00FF) + relative > 0x100) {
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cycles++;
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}
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cycles++;
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program_counter += relative;
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}
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}
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void CPU::op_beq(int8_t relative) {
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if (FLAG_ZERO) {
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//+1 cycle for branching, +2 if branching to a different page
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if ((program_counter & 0x00FF) + relative > 0x100) {
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cycles++;
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}
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cycles++;
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program_counter += relative;
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}
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}
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void CPU::op_bit(WideAddress address) {
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/*
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Logic:
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t = A & M
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P.N = M.7
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P.V = M.6
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P.Z = (t==0) ? 1:0
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*/
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uint8_t operand = fetch_memory_byte(address, false);
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uint8_t t = accumulator & operand;
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PN = (operand & 0x80) == 0x80;
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PV = (operand & 0x40) == 0x40;
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PZ = (t == 0);
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}
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void CPU::op_bmi(int8_t relative) {
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if (PN) {
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//+1 cycle for branching, +2 if branching to a different page
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if ((program_counter & 0x00FF) + relative > 0x100) {
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cycles++;
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}
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cycles++;
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program_counter += relative;
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}
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}
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void CPU::op_bne(int8_t relative) {
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if (!PZ) {
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cycles++;
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program_counter += relative;
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if (relative == (int8_t)0xFE) {
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std::exit(4);
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}
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}
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}
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void CPU::op_bpl(int8_t relative) {
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if (!PN) {
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//+1 cycle for branching, +2 if branching to a different page
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if ((program_counter & 0x00FF) + relative > 0x100) {
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cycles++;
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}
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cycles++;
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program_counter += relative;
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}
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}
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void CPU::op_brk() {
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uint8_t psw = getProgramStatusWord();
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setProgramStatusWord(psw |= 0x10); //enable the B flag
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psw |= 0x10; //we push the B flag as 1
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WideAddress pc = uintAddressToWideAddress(program_counter);
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stack_push(pc.high);
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stack_push(pc.low);
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stack_push(psw);
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program_counter = WideAddress{ fetch_memory_byte(0xFFFF, false), fetch_memory_byte(0xFFFE, false) };
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}
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void CPU::op_bvc(int8_t relative) {
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if (!PV) {
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//+1 cycle for branching, +2 if branching to a different page
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if ((program_counter & 0x00FF) + relative > 0x100) {
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cycles++;
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}
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cycles++;
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program_counter += relative;
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}
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}
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void CPU::op_bvs(int8_t relative) {
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if (PV) {
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//+1 cycle for branching, +2 if branching to a different page
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if ((program_counter & 0x00FF) + relative > 0x100) {
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cycles++;
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}
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cycles++;
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program_counter += relative;
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}
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}
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void CPU::op_clc() {
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PC = false;
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}
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void CPU::op_cld() {
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PD = false;
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}
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void CPU::op_cli() {
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PI = false;
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}
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void CPU::op_clv() {
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PV = false;
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}
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void CPU::op_cmp(uint8_t immediate, bool crossedPageBoundary) { //immediate
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/*
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Logic:
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t = A - M
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P.N = t.7
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P.C = (A>=M) ? 1:0
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P.Z = (t==0) ? 1:0
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*/
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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uint8_t t = accumulator - immediate;
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PN = (t & 0x80) == 0x80;
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PC = (accumulator >= immediate);
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PZ = (t == 0);
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}
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void CPU::op_cmp(WideAddress address, bool crossedPageBoundary) {
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/*
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Logic:
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t = A - M
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P.N = t.7
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P.C = (A>=M) ? 1:0
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P.Z = (t==0) ? 1:0
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*/
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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uint8_t t = accumulator - fetch_memory_byte(address, false);
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PN = (t & 0x80) == 0x80;
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PC = (accumulator >= fetch_memory_byte(address, false));
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PZ = (t == 0);
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}
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void CPU::op_cpx(uint8_t immediate) {
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uint8_t t = index_x - immediate;
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PN = (t & 0x80) == 0x80;
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PC = (index_x >= immediate);
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PZ = (t == 0);
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}
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void CPU::op_cpx(WideAddress address) {
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uint8_t t = index_x - fetch_memory_byte(address, false);
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PN = (t & 0x80) == 0x80;
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PC = (index_x >= fetch_memory_byte(address, false));
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PZ = (t == 0);
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}
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void CPU::op_cpy(uint8_t immediate) {
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uint8_t t = index_y - immediate;
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PN = (t & 0x80) == 0x80;
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PC = (index_y >= immediate);
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PZ = (t == 0);
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}
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void CPU::op_cpy(WideAddress address) {
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uint8_t t = index_y - fetch_memory_byte(address, false);
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PN = (t & 0x80) == 0x80;
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PC = (index_y >= fetch_memory_byte(address, false));
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PZ = (t == 0);
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}
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void CPU::op_dec(WideAddress address) {
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/*
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Logic:
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M = (M - 1) & $FF
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P.N = M.7
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P.Z = (M==0) ? 1:0
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*/
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write_memory_byte(address, (fetch_memory_byte(address, false) - 1) & 0xFF);
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PN = (fetch_memory_byte(address, false) & 0x80) == 0x80;
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PZ = (fetch_memory_byte(address, false) == 0);
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}
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void CPU::op_dex() {
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index_x--;
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PZ = (index_x == 0);
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PN = (index_x & 0x80) == 0x80;
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}
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void CPU::op_dey() {
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index_y--;
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PZ = (index_y == 0);
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PN = (index_y & 0x80) == 0x80;
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}
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void CPU::op_eor(uint8_t immediate, bool crossedPageBoundary) {
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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accumulator = accumulator ^ immediate;
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PN = (accumulator & 0x80) == 0x80;
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PZ = (accumulator == 0);
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}
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void CPU::op_eor(WideAddress address, bool crossedPageBoundary) {
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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accumulator = accumulator ^ fetch_memory_byte(address, false);
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PN = (accumulator & 0x80) == 0x80;
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PZ = (accumulator == 0);
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}
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void CPU::op_inc(WideAddress address) {
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/*
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Logic:
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M = (M + 1) & $FF
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P.N = M.7
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P.Z = (M==0) ? 1:0
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*/
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write_memory_byte(address, (fetch_memory_byte(address, false) + 1) & 0xFF);
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PN = (fetch_memory_byte(address, false) & 0x80) == 0x80;
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PZ = (fetch_memory_byte(address, false) == 0);
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}
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void CPU::op_inx() {
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index_x++;
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PZ = (index_x == 0);
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PN = (index_x & 0x80) == 0x80;
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}
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void CPU::op_iny() {
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index_y++;
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PZ = (index_y == 0);
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PN = (index_y & 0x80) == 0x80;
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}
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void CPU::op_jmp(WideAddress address) {
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program_counter = address;
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}
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void CPU::op_jsr(WideAddress address) {
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/*
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Logic:
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t = PC - 1
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bPoke(SP, t.h)
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SP = SP - 1
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bPoke(SP, t.l)
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SP = SP - 1
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PC = address
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*/
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WideAddress t = uintAddressToWideAddress(program_counter - 1);
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stack_push(t.high);
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stack_push(t.low);
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program_counter = address;
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}
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void CPU::op_lda(uint8_t immediate, bool crossedPageBoundary) {
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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accumulator = immediate;
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PN = (accumulator & 0x80) == 0x80;
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PZ = (accumulator == 0);
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}
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void CPU::op_lda(WideAddress address, bool crossedPageBoundary) {
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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accumulator = fetch_memory_byte(address, false);
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PN = (accumulator & 0x80) == 0x80;
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PZ = (accumulator == 0);
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}
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void CPU::op_ldx(uint8_t immediate, bool crossedPageBoundary) {
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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index_x = immediate;
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PN = (index_x & 0x80) == 0x80;
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PZ = (index_x == 0);
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}
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void CPU::op_ldx(WideAddress address, bool crossedPageBoundary) {
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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index_x = fetch_memory_byte(address, false);
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PN = (index_x & 0x80) == 0x80;
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PZ = (index_x == 0);
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}
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void CPU::op_ldy(uint8_t immediate, bool crossedPageBoundary) {
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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index_y = immediate;
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PN = (index_y & 0x80) == 0x80;
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PZ = (index_y == 0);
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}
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void CPU::op_ldy(WideAddress address, bool crossedPageBoundary) {
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if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
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cycles++;
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}
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index_y = fetch_memory_byte(address, false);
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PN = (index_y & 0x80) == 0x80;
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PZ = (index_y == 0);
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}
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void CPU::op_lsr() { //Accumulator
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/*
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Logic:
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P.N = 0
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P.C = B.0
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B = (B >> 1) & $7F
|
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P.Z = (B==0) ? 1:0
|
|
*/
|
|
PN = false;
|
|
PC = (accumulator & 0x01) == 0x01;
|
|
accumulator = (accumulator >> 1) & 0x7F;
|
|
PZ = (accumulator == 0);
|
|
}
|
|
|
|
void CPU::op_lsr(WideAddress address) { //OK
|
|
/*
|
|
Logic:
|
|
P.N = 0
|
|
P.C = B.0
|
|
B = (B >> 1) & $7F
|
|
P.Z = (B==0) ? 1:0
|
|
*/
|
|
PN = false;
|
|
PC = (fetch_memory_byte(address, false) & 0x01) == 0x01;
|
|
write_memory_byte(address, ((fetch_memory_byte(address, false) >> 1) & 0x7F));
|
|
PZ = (fetch_memory_byte(address, false) == 0);
|
|
}
|
|
|
|
void CPU::op_nop() {
|
|
//NOP
|
|
}
|
|
|
|
void CPU::op_ora(uint8_t immediate, bool crossedPageBoundary) {
|
|
|
|
if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
|
|
cycles++;
|
|
}
|
|
|
|
accumulator = accumulator | immediate;
|
|
PN = (accumulator & 0x80) == 0x80;
|
|
PZ = (accumulator == 0);
|
|
}
|
|
|
|
void CPU::op_ora(WideAddress address, bool crossedPageBoundary) {
|
|
|
|
if (crossedPageBoundary && lastInstructionCrossedPageBoundary) {
|
|
cycles++;
|
|
}
|
|
|
|
accumulator = accumulator | fetch_memory_byte(address, false);
|
|
PN = (accumulator & 0x80) == 0x80;
|
|
PZ = (accumulator == 0);
|
|
}
|
|
|
|
void CPU::op_pha() {
|
|
stack_push(accumulator);
|
|
}
|
|
|
|
void CPU::op_php() {
|
|
stack_push(getProgramStatusWord() | 0x10);
|
|
}
|
|
|
|
void CPU::op_pla() {
|
|
accumulator = stack_pop();
|
|
PN = (accumulator & 0x80) == 0x80;
|
|
PZ = (accumulator == 0);
|
|
}
|
|
|
|
void CPU::op_plp() {
|
|
setProgramStatusWord(stack_pop());
|
|
}
|
|
|
|
void CPU::op_rol() { //Tested and working
|
|
/*
|
|
Logic:
|
|
t = B.7
|
|
B = (B << 1) & $FE
|
|
B = B | P.C
|
|
P.C = t
|
|
P.Z = (B==0) ? 1:0
|
|
P.N = B.7
|
|
*/
|
|
bool t = (accumulator & 0x80) == 0x80;
|
|
accumulator = (accumulator << 1) & 0xFE;
|
|
if (PC) {
|
|
accumulator = accumulator | 0x01;
|
|
}
|
|
PC = t;
|
|
PN = (accumulator & 0x80) == 0x80;
|
|
PZ = (accumulator == 0);
|
|
}
|
|
|
|
void CPU::op_rol(WideAddress address) { //Tested and working
|
|
/*
|
|
Logic:
|
|
t = B.7
|
|
B = (B << 1) & $FE
|
|
B = B | P.C
|
|
P.C = t
|
|
P.Z = (B==0) ? 1:0
|
|
P.N = B.7
|
|
*/
|
|
bool t = (fetch_memory_byte(address, false) & 0x80) == 0x80;
|
|
write_memory_byte(address, (fetch_memory_byte(address, false) << 1) & 0xFE);
|
|
if (PC) {
|
|
write_memory_byte(address, fetch_memory_byte(address, false) | 0x01);
|
|
}
|
|
PC = t;
|
|
PN = (fetch_memory_byte(address, false) & 0x80) == 0x80;
|
|
PZ = (fetch_memory_byte(address, false) == 0);
|
|
}
|
|
|
|
void CPU::op_ror() { //Tested and working
|
|
/*
|
|
Logic:
|
|
t = B.0
|
|
B = (B >> 1) & $7F
|
|
B = B | ((P.C) ? $80:$00)
|
|
P.C = t
|
|
P.Z = (B==0) ? 1:0
|
|
P.N = B.7
|
|
*/
|
|
bool t = (accumulator & 0x01) == 0x01;
|
|
accumulator = (accumulator >> 1) & 0x7F;
|
|
if (PC) {
|
|
accumulator |= 0x80;
|
|
}
|
|
PC = t;
|
|
PN = (accumulator & 0x80) == 0x80;
|
|
PZ = (accumulator == 0);
|
|
}
|
|
|
|
void CPU::op_ror(WideAddress address) { //Tested and working
|
|
bool t = (fetch_memory_byte(address, false) & 0x01) == 0x01;
|
|
write_memory_byte(address, (fetch_memory_byte(address, false) >> 1) & 0x7F);
|
|
if (PC) {
|
|
write_memory_byte(address, (fetch_memory_byte(address, false) | 0x80));
|
|
}
|
|
PC = t;
|
|
PN = (fetch_memory_byte(address, false) & 0x80) == 0x80;
|
|
PZ = (fetch_memory_byte(address, false) == 0);
|
|
}
|
|
|
|
void CPU::op_rti() {
|
|
setProgramStatusWord(stack_pop());
|
|
uint8_t lo = stack_pop();
|
|
uint8_t hi = stack_pop();
|
|
program_counter = WideAddress{ hi, lo };
|
|
}
|
|
|
|
void CPU::op_rts() {
|
|
uint8_t lo = stack_pop();
|
|
uint8_t hi = stack_pop();
|
|
WideAddress addr = WideAddress{ hi, lo };
|
|
program_counter = addr.add(1, false);
|
|
}
|
|
|
|
void CPU::op_sbc(uint8_t immediate, bool crossedPageBoundary) {
|
|
/*
|
|
Logic:
|
|
IF (P.D)
|
|
t = bcd(A) - bcd(M) - !P.C
|
|
P.V = (t>99 OR t<0) ? 1:0
|
|
ELSE
|
|
t = A - M - !P.C
|
|
P.V = (t>127 OR t<-128) ? 1:0
|
|
P.C = (t>=0) ? 1:0
|
|
P.N = t.7
|
|
P.Z = (t==0) ? 1:0
|
|
A = t & 0xFF
|
|
*/
|
|
//TODO: decimal
|
|
|
|
op_adc(~immediate, crossedPageBoundary);
|
|
|
|
/*
|
|
int8_t t;
|
|
|
|
if (PD) {
|
|
t = hex2bcd(accumulator) - hex2bcd(immediate) - !PC;
|
|
PV = (t > 99 || t < 0);
|
|
}
|
|
else {
|
|
t = accumulator - immediate - !PC;
|
|
PV = (t > 127 || t < -128);
|
|
}
|
|
PC = (t >= 0);
|
|
PN = (t & 0x80) == 0x80;
|
|
PZ = (t == 0);
|
|
accumulator = (t & 0xFF);
|
|
*/
|
|
}
|
|
|
|
void CPU::op_sbc(WideAddress address, bool crossedPageBoundary) {
|
|
op_adc(~fetch_memory_byte(address, false), crossedPageBoundary);
|
|
|
|
/*
|
|
int8_t t;
|
|
|
|
if (PD) {
|
|
t = hex2bcd(accumulator) - hex2bcd(fetch_memory_byte(address, false)) - !PC;
|
|
PV = (t > 99 || t < 0);
|
|
}
|
|
else {
|
|
t = accumulator - fetch_memory_byte(address, false) - !PC;
|
|
PV = (t > 127 || t < -128);
|
|
}
|
|
|
|
PC = (t >= 0);
|
|
PN = (t & 0x80) == 0x80;
|
|
PZ = (t == 0);
|
|
accumulator = (t & 0xFF);
|
|
*/
|
|
}
|
|
|
|
void CPU::op_sec() {
|
|
PC = true;
|
|
}
|
|
|
|
void CPU::op_sed() {
|
|
PD = true;
|
|
}
|
|
|
|
void CPU::op_sei() {
|
|
PI = true;
|
|
}
|
|
|
|
void CPU::op_sta(WideAddress address) {
|
|
write_memory_byte(address, accumulator);
|
|
}
|
|
|
|
void CPU::op_stx(WideAddress address) {
|
|
write_memory_byte(address, index_x);
|
|
}
|
|
|
|
void CPU::op_sty(WideAddress address) {
|
|
write_memory_byte(address, index_y);
|
|
}
|
|
|
|
void CPU::op_tax() {
|
|
index_x = accumulator;
|
|
PN = (index_x & 0x80) == 0x80;
|
|
PZ = (index_x == 0);
|
|
}
|
|
|
|
void CPU::op_tay() {
|
|
index_y = accumulator;
|
|
PN = (index_y & 0x80) == 0x80;
|
|
PZ = (index_y == 0);
|
|
}
|
|
|
|
void CPU::op_tsx() {
|
|
index_x = stack_pointer;
|
|
PN = (index_x & 0x80) == 0x80;
|
|
PZ = (index_x == 0);
|
|
}
|
|
|
|
void CPU::op_txa() {
|
|
accumulator = index_x;
|
|
PN = (accumulator & 0x80) == 0x80;
|
|
PZ = (accumulator == 0);
|
|
}
|
|
|
|
void CPU::op_txs() {
|
|
stack_pointer = index_x;
|
|
}
|
|
|
|
void CPU::op_tya() {
|
|
accumulator = index_y;
|
|
PN = (accumulator & 0x80) == 0x80;
|
|
PZ = (accumulator == 0);
|
|
} |