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Ensure 6502 uses memory rather than bus read/write mechanism

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Signed-off-by: Adrian Conlon <adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2021-03-08 16:44:09 +00:00
parent 4dd3106af0
commit b1ca06447f
2 changed files with 66 additions and 66 deletions
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2
M6502/inc/mos6502.h
View File

@ -138,7 +138,7 @@ namespace EightBit {
return data;
}
void busReadModifyWrite(const uint8_t data) {
void memoryReadModifyWrite(const uint8_t data) {
// The read will have already taken place...
memoryWrite();
memoryWrite(data);

130
M6502/src/mos6502.cpp
View File

@ -118,15 +118,15 @@ int EightBit::MOS6502::execute() {
case 0x03: slo(AM_IndexedIndirectX()); break; // *SLO (indexed indirect X)
case 0x04: AM_ZeroPage(); break; // *NOP (zero page)
case 0x05: A() = orr(A(), AM_ZeroPage()); break; // ORA (zero page)
case 0x06: busReadModifyWrite(asl(AM_ZeroPage())); break; // ASL (zero page)
case 0x06: memoryReadModifyWrite(asl(AM_ZeroPage())); break; // ASL (zero page)
case 0x07: slo(AM_ZeroPage()); break; // *SLO (zero page)
case 0x08: busRead(); php(); break; // PHP (implied)
case 0x08: memoryRead(); php(); break; // PHP (implied)
case 0x09: A() = orr(A(), AM_Immediate()); break; // ORA (immediate)
case 0x0a: busRead(); A() = asl(A()); break; // ASL A (implied)
case 0x0a: memoryRead(); A() = asl(A()); break; // ASL A (implied)
case 0x0b: anc(AM_Immediate()); break; // *ANC (immediate)
case 0x0c: AM_Absolute(); break; // *NOP (absolute)
case 0x0d: A() = orr(A(), AM_Absolute()); break; // ORA (absolute)
case 0x0e: busReadModifyWrite(asl(AM_Absolute())); break; // ASL (absolute)
case 0x0e: memoryReadModifyWrite(asl(AM_Absolute())); break; // ASL (absolute)
case 0x0f: slo(AM_Absolute()); break; // *SLO (absolute)
case 0x10: branch(!negative()); break; // BPL (relative)
@ -135,15 +135,15 @@ int EightBit::MOS6502::execute() {
case 0x13: slo(AM_IndirectIndexedY()); break; // *SLO (indirect indexed Y)
case 0x14: AM_ZeroPageX(); break; // *NOP (zero page, X)
case 0x15: A() = orr(A(), AM_ZeroPageX()); break; // ORA (zero page, X)
case 0x16: busReadModifyWrite(asl(AM_ZeroPageX())); break; // ASL (zero page, X)
case 0x16: memoryReadModifyWrite(asl(AM_ZeroPageX())); break; // ASL (zero page, X)
case 0x17: slo(AM_ZeroPageX()); break; // *SLO (zero page, X)
case 0x18: busRead(); P() = clearBit(P(), CF); break; // CLC (implied)
case 0x18: memoryRead(); P() = clearBit(P(), CF); break; // CLC (implied)
case 0x19: A() = orr(A(), AM_AbsoluteY()); break; // ORA (absolute, Y)
case 0x1a: busRead(); break; // *NOP (implied)
case 0x1a: memoryRead(); break; // *NOP (implied)
case 0x1b: slo(AM_AbsoluteY()); break; // *SLO (absolute, Y)
case 0x1c: AM_AbsoluteX(); break; // *NOP (absolute, X)
case 0x1d: A() = orr(A(), AM_AbsoluteX()); break; // ORA (absolute, X)
case 0x1e: busReadModifyWrite(asl(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // ASL (absolute, X)
case 0x1e: memoryReadModifyWrite(asl(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // ASL (absolute, X)
case 0x1f: slo(AM_AbsoluteX()); break; // *SLO (absolute, X)
case 0x20: jsr(); break; // JSR (absolute)
@ -152,15 +152,15 @@ int EightBit::MOS6502::execute() {
case 0x23: rla(AM_IndexedIndirectX()); break; // *RLA (indexed indirect X)
case 0x24: bit(A(), AM_ZeroPage()); break; // BIT (zero page)
case 0x25: A() = andr(A(), AM_ZeroPage()); break; // AND (zero page)
case 0x26: busReadModifyWrite(rol(AM_ZeroPage())); break; // ROL (zero page)
case 0x26: memoryReadModifyWrite(rol(AM_ZeroPage())); break; // ROL (zero page)
case 0x27: rla(AM_ZeroPage()); break; // *RLA (zero page)
case 0x28: busRead(); getBytePaged(1, S()); plp(); break; // PLP (implied)
case 0x28: memoryRead(); getBytePaged(1, S()); plp(); break; // PLP (implied)
case 0x29: A() = andr(A(), AM_Immediate()); break; // AND (immediate)
case 0x2a: busRead(); A() = rol(A()); break; // ROL A (implied)
case 0x2a: memoryRead(); A() = rol(A()); break; // ROL A (implied)
case 0x2b: anc(AM_Immediate()); break; // *ANC (immediate)
case 0x2c: bit(A(), AM_Absolute()); break; // BIT (absolute)
case 0x2d: A() = andr(A(), AM_Absolute()); break; // AND (absolute)
case 0x2e: busReadModifyWrite(rol(AM_Absolute())); break; // ROL (absolute)
case 0x2e: memoryReadModifyWrite(rol(AM_Absolute())); break; // ROL (absolute)
case 0x2f: rla(AM_Absolute()); break; // *RLA (absolute)
case 0x30: branch(negative()); break; // BMI (relative)
@ -169,32 +169,32 @@ int EightBit::MOS6502::execute() {
case 0x33: rla(AM_IndirectIndexedY()); break; // *RLA (indirect indexed Y)
case 0x34: AM_ZeroPageX(); break; // *NOP (zero page, X)
case 0x35: A() = andr(A(), AM_ZeroPageX()); break; // AND (zero page, X)
case 0x36: busReadModifyWrite(rol(AM_ZeroPageX())); break; // ROL (zero page, X)
case 0x36: memoryReadModifyWrite(rol(AM_ZeroPageX())); break; // ROL (zero page, X)
case 0x37: rla(AM_ZeroPageX()); break; // *RLA (zero page, X)
case 0x38: busRead(); P() = setBit(P(), CF); break; // SEC (implied)
case 0x38: memoryRead(); P() = setBit(P(), CF); break; // SEC (implied)
case 0x39: A() = andr(A(), AM_AbsoluteY()); break; // AND (absolute, Y)
case 0x3a: busRead(); break; // *NOP (implied)
case 0x3a: memoryRead(); break; // *NOP (implied)
case 0x3b: rla(AM_AbsoluteY()); break; // *RLA (absolute, Y)
case 0x3c: AM_AbsoluteX(); break; // *NOP (absolute, X)
case 0x3d: A() = andr(A(), AM_AbsoluteX()); break; // AND (absolute, X)
case 0x3e: busReadModifyWrite(rol(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // ROL (absolute, X)
case 0x3e: memoryReadModifyWrite(rol(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // ROL (absolute, X)
case 0x3f: rla(AM_AbsoluteX()); break; // *RLA (absolute, X)
case 0x40: busRead(); rti(); break; // RTI (implied)
case 0x40: memoryRead(); rti(); break; // RTI (implied)
case 0x41: A() = eorr(A(), AM_IndexedIndirectX()); break; // EOR (indexed indirect X)
case 0x42: break;
case 0x43: sre(AM_IndexedIndirectX()); break; // *SRE (indexed indirect X)
case 0x44: AM_ZeroPage(); break; // *NOP (zero page)
case 0x45: A() = eorr(A(), AM_ZeroPage()); break; // EOR (zero page)
case 0x46: busReadModifyWrite(lsr(AM_ZeroPage())); break; // LSR (zero page)
case 0x46: memoryReadModifyWrite(lsr(AM_ZeroPage())); break; // LSR (zero page)
case 0x47: sre(AM_ZeroPage()); break; // *SRE (zero page)
case 0x48: busRead(); push(A()); break; // PHA (implied)
case 0x48: memoryRead(); push(A()); break; // PHA (implied)
case 0x49: A() = eorr(A(), AM_Immediate()); break; // EOR (immediate)
case 0x4a: busRead(); A() = lsr(A()); break; // LSR A (implied)
case 0x4a: memoryRead(); A() = lsr(A()); break; // LSR A (implied)
case 0x4b: asr(AM_Immediate()); break; // *ASR (immediate)
case 0x4c: jump(Address_Absolute()); break; // JMP (absolute)
case 0x4d: A() = eorr(A(), AM_Absolute()); break; // EOR (absolute)
case 0x4e: busReadModifyWrite(lsr(AM_Absolute())); break; // LSR (absolute)
case 0x4e: memoryReadModifyWrite(lsr(AM_Absolute())); break; // LSR (absolute)
case 0x4f: sre(AM_Absolute()); break; // *SRE (absolute)
case 0x50: branch(!overflow()); break; // BVC (relative)
@ -203,32 +203,32 @@ int EightBit::MOS6502::execute() {
case 0x53: sre(AM_IndirectIndexedY()); break; // *SRE (indirect indexed Y)
case 0x54: AM_ZeroPageX(); break; // *NOP (zero page, X)
case 0x55: A() = eorr(A(), AM_ZeroPageX()); break; // EOR (zero page, X)
case 0x56: busReadModifyWrite(lsr(AM_ZeroPageX())); break; // LSR (zero page, X)
case 0x56: memoryReadModifyWrite(lsr(AM_ZeroPageX())); break; // LSR (zero page, X)
case 0x57: sre(AM_ZeroPageX()); break; // *SRE (zero page, X)
case 0x58: busRead(); P() = clearBit(P(), IF); break; // CLI (implied)
case 0x58: memoryRead(); P() = clearBit(P(), IF); break; // CLI (implied)
case 0x59: A() = eorr(A(), AM_AbsoluteY()); break; // EOR (absolute, Y)
case 0x5a: busRead(); break; // *NOP (implied)
case 0x5a: memoryRead(); break; // *NOP (implied)
case 0x5b: sre(AM_AbsoluteY()); break; // *SRE (absolute, Y)
case 0x5c: AM_AbsoluteX(); break; // *NOP (absolute, X)
case 0x5d: A() = eorr(A(), AM_AbsoluteX()); break; // EOR (absolute, X)
case 0x5e: busReadModifyWrite(lsr(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // LSR (absolute, X)
case 0x5e: memoryReadModifyWrite(lsr(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // LSR (absolute, X)
case 0x5f: sre(AM_AbsoluteX()); break; // *SRE (absolute, X)
case 0x60: busRead(); rts(); break; // RTS (implied)
case 0x60: memoryRead(); rts(); break; // RTS (implied)
case 0x61: A() = adc(A(), AM_IndexedIndirectX()); break; // ADC (indexed indirect X)
case 0x62: break;
case 0x63: rra(AM_IndexedIndirectX()); break; // *RRA (indexed indirect X)
case 0x64: AM_ZeroPage(); break; // *NOP (zero page)
case 0x65: A() = adc(A(), AM_ZeroPage()); break; // ADC (zero page)
case 0x66: busReadModifyWrite(ror(AM_ZeroPage())); break; // ROR (zero page)
case 0x66: memoryReadModifyWrite(ror(AM_ZeroPage())); break; // ROR (zero page)
case 0x67: rra(AM_ZeroPage()); break; // *RRA (zero page)
case 0x68: busRead(); getBytePaged(1, S()); A() = through(pop()); break; // PLA (implied)
case 0x68: memoryRead(); getBytePaged(1, S()); A() = through(pop()); break; // PLA (implied)
case 0x69: A() = adc(A(), AM_Immediate()); break; // ADC (immediate)
case 0x6a: busRead(); A() = ror(A()); break; // ROR A (implied)
case 0x6a: memoryRead(); A() = ror(A()); break; // ROR A (implied)
case 0x6b: arr(AM_Immediate()); break; // *ARR (immediate)
case 0x6c: jump(Address_Indirect()); break; // JMP (indirect)
case 0x6d: A() = adc(A(), AM_Absolute()); break; // ADC (absolute)
case 0x6e: busReadModifyWrite(ror(AM_Absolute())); break; // ROR (absolute)
case 0x6e: memoryReadModifyWrite(ror(AM_Absolute())); break; // ROR (absolute)
case 0x6f: rra(AM_Absolute()); break; // *RRA (absolute)
case 0x70: branch(overflow()); break; // BVS (relative)
@ -237,15 +237,15 @@ int EightBit::MOS6502::execute() {
case 0x73: rra(AM_IndirectIndexedY()); break; // *RRA (indirect indexed Y)
case 0x74: AM_ZeroPageX(); break; // *NOP (zero page, X)
case 0x75: A() = adc(A(), AM_ZeroPageX()); break; // ADC (zero page, X)
case 0x76: busReadModifyWrite(ror(AM_ZeroPageX())); break; // ROR (zero page, X)
case 0x76: memoryReadModifyWrite(ror(AM_ZeroPageX())); break; // ROR (zero page, X)
case 0x77: rra(AM_ZeroPageX()); break; // *RRA (zero page, X)
case 0x78: busRead(); P() = setBit(P(), IF); break; // SEI (implied)
case 0x78: memoryRead(); P() = setBit(P(), IF); break; // SEI (implied)
case 0x79: A() = adc(A(), AM_AbsoluteY()); break; // ADC (absolute, Y)
case 0x7a: busRead(); break; // *NOP (implied)
case 0x7a: memoryRead(); break; // *NOP (implied)
case 0x7b: rra(AM_AbsoluteY()); break; // *RRA (absolute, Y)
case 0x7c: AM_AbsoluteX(); break; // *NOP (absolute, X)
case 0x7d: A() = adc(A(), AM_AbsoluteX()); break; // ADC (absolute, X)
case 0x7e: busReadModifyWrite(ror(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // ROR (absolute, X)
case 0x7e: memoryReadModifyWrite(ror(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // ROR (absolute, X)
case 0x7f: rra(AM_AbsoluteX()); break; // *RRA (absolute, X)
case 0x80: AM_Immediate(); break; // *NOP (immediate)
@ -256,9 +256,9 @@ int EightBit::MOS6502::execute() {
case 0x85: memoryWrite(Address_ZeroPage(), A()); break; // STA (zero page)
case 0x86: memoryWrite(Address_ZeroPage(), X()); break; // STX (zero page)
case 0x87: memoryWrite(Address_ZeroPage(), A() & X()); break; // *SAX (zero page)
case 0x88: busRead(); Y() = dec(Y()); break; // DEY (implied)
case 0x88: memoryRead(); Y() = dec(Y()); break; // DEY (implied)
case 0x89: AM_Immediate(); break; // *NOP (immediate)
case 0x8a: busRead(); A() = through(X()); break; // TXA (implied)
case 0x8a: memoryRead(); A() = through(X()); break; // TXA (implied)
case 0x8b: break;
case 0x8c: memoryWrite(Address_Absolute(), Y()); break; // STY (absolute)
case 0x8d: memoryWrite(Address_Absolute(), A()); break; // STA (absolute)
@ -273,9 +273,9 @@ int EightBit::MOS6502::execute() {
case 0x95: memoryWrite(Address_ZeroPageX(), A()); break; // STA (zero page, X)
case 0x96: memoryWrite(Address_ZeroPageY(), X()); break; // STX (zero page, Y)
case 0x97: memoryWrite(Address_ZeroPageY(), A() & X()); break; // *SAX (zero page, Y)
case 0x98: busRead(); A() = through(Y()); break; // TYA (implied)
case 0x98: memoryRead(); A() = through(Y()); break; // TYA (implied)
case 0x99: sta_AbsoluteY(); break; // STA (absolute, Y)
case 0x9a: busRead(); S() = X(); break; // TXS (implied)
case 0x9a: memoryRead(); S() = X(); break; // TXS (implied)
case 0x9b: break;
case 0x9c: break;
case 0x9d: sta_AbsoluteX(); break; // STA (absolute, X)
@ -290,9 +290,9 @@ int EightBit::MOS6502::execute() {
case 0xa5: A() = through(AM_ZeroPage()); break; // LDA (zero page)
case 0xa6: X() = through(AM_ZeroPage()); break; // LDX (zero page)
case 0xa7: A() = X() = through(AM_ZeroPage()); break; // *LAX (zero page)
case 0xa8: busRead(); Y() = through(A()); break; // TAY (implied)
case 0xa8: memoryRead(); Y() = through(A()); break; // TAY (implied)
case 0xa9: A() = through(AM_Immediate()); break; // LDA (immediate)
case 0xaa: busRead(); X() = through(A()); break; // TAX (implied)
case 0xaa: memoryRead(); X() = through(A()); break; // TAX (implied)
case 0xab: A() = X() = through(AM_Immediate()); break; // *ATX (immediate)
case 0xac: Y() = through(AM_Absolute()); break; // LDY (absolute)
case 0xad: A() = through(AM_Absolute()); break; // LDA (absolute)
@ -307,9 +307,9 @@ int EightBit::MOS6502::execute() {
case 0xb5: A() = through(AM_ZeroPageX()); break; // LDA (zero page, X)
case 0xb6: X() = through(AM_ZeroPageY()); break; // LDX (zero page, Y)
case 0xb7: A() = X() = through(AM_ZeroPageY()); break; // *LAX (zero page, Y)
case 0xb8: busRead(); P() = clearBit(P(), VF); break; // CLV (implied)
case 0xb8: memoryRead(); P() = clearBit(P(), VF); break; // CLV (implied)
case 0xb9: A() = through(AM_AbsoluteY()); break; // LDA (absolute, Y)
case 0xba: busRead(); X() = through(S()); break; // TSX (implied)
case 0xba: memoryRead(); X() = through(S()); break; // TSX (implied)
case 0xbb: break;
case 0xbc: Y() = through(AM_AbsoluteX()); break; // LDY (absolute, X)
case 0xbd: A() = through(AM_AbsoluteX()); break; // LDA (absolute, X)
@ -322,15 +322,15 @@ int EightBit::MOS6502::execute() {
case 0xc3: dcp(AM_IndexedIndirectX()); break; // *DCP (indexed indirect X)
case 0xc4: cmp(Y(), AM_ZeroPage()); break; // CPY (zero page)
case 0xc5: cmp(A(), AM_ZeroPage()); break; // CMP (zero page)
case 0xc6: busReadModifyWrite(dec(AM_ZeroPage())); break; // DEC (zero page)
case 0xc6: memoryReadModifyWrite(dec(AM_ZeroPage())); break; // DEC (zero page)
case 0xc7: dcp(AM_ZeroPage()); break; // *DCP (zero page)
case 0xc8: busRead(); Y() = inc(Y()); break; // INY (implied)
case 0xc8: memoryRead(); Y() = inc(Y()); break; // INY (implied)
case 0xc9: cmp(A(), AM_Immediate()); break; // CMP (immediate)
case 0xca: busRead(); X() = dec(X()); break; // DEX (implied)
case 0xca: memoryRead(); X() = dec(X()); break; // DEX (implied)
case 0xcb: axs(AM_Immediate()); break; // *AXS (immediate)
case 0xcc: cmp(Y(), AM_Absolute()); break; // CPY (absolute)
case 0xcd: cmp(A(), AM_Absolute()); break; // CMP (absolute)
case 0xce: busReadModifyWrite(dec(AM_Absolute())); break; // DEC (absolute)
case 0xce: memoryReadModifyWrite(dec(AM_Absolute())); break; // DEC (absolute)
case 0xcf: dcp(AM_Absolute()); break; // *DCP (absolute)
case 0xd0: branch(!zero()); break; // BNE (relative)
@ -339,15 +339,15 @@ int EightBit::MOS6502::execute() {
case 0xd3: dcp(AM_IndirectIndexedY()); break; // *DCP (indirect indexed Y)
case 0xd4: AM_ZeroPageX(); break; // *NOP (zero page, X)
case 0xd5: cmp(A(), AM_ZeroPageX()); break; // CMP (zero page, X)
case 0xd6: busReadModifyWrite(dec(AM_ZeroPageX())); break; // DEC (zero page, X)
case 0xd6: memoryReadModifyWrite(dec(AM_ZeroPageX())); break; // DEC (zero page, X)
case 0xd7: dcp(AM_ZeroPageX()); break; // *DCP (zero page, X)
case 0xd8: busRead(); P() = clearBit(P(), DF); break; // CLD (implied)
case 0xd8: memoryRead(); P() = clearBit(P(), DF); break; // CLD (implied)
case 0xd9: cmp(A(), AM_AbsoluteY()); break; // CMP (absolute, Y)
case 0xda: busRead(); break; // *NOP (implied)
case 0xda: memoryRead(); break; // *NOP (implied)
case 0xdb: dcp(AM_AbsoluteY()); break; // *DCP (absolute, Y)
case 0xdc: AM_AbsoluteX(); break; // *NOP (absolute, X)
case 0xdd: cmp(A(), AM_AbsoluteX()); break; // CMP (absolute, X)
case 0xde: busReadModifyWrite(dec(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // DEC (absolute, X)
case 0xde: memoryReadModifyWrite(dec(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // DEC (absolute, X)
case 0xdf: dcp(AM_AbsoluteX()); break; // *DCP (absolute, X)
case 0xe0: cmp(X(), AM_Immediate()); break; // CPX (immediate)
@ -356,15 +356,15 @@ int EightBit::MOS6502::execute() {
case 0xe3: isb(AM_IndexedIndirectX()); break; // *ISB (indexed indirect X)
case 0xe4: cmp(X(), AM_ZeroPage()); break; // CPX (zero page)
case 0xe5: A() = sbc(A(), AM_ZeroPage()); break; // SBC (zero page)
case 0xe6: busReadModifyWrite(inc(AM_ZeroPage())); break; // INC (zero page)
case 0xe6: memoryReadModifyWrite(inc(AM_ZeroPage())); break; // INC (zero page)
case 0xe7: isb(AM_ZeroPage()); break; // *ISB (zero page)
case 0xe8: busRead(); X() = inc(X()); break; // INX (implied)
case 0xe8: memoryRead(); X() = inc(X()); break; // INX (implied)
case 0xe9: A() = sbc(A(), AM_Immediate()); break; // SBC (immediate)
case 0xea: busRead(); break; // NOP (implied)
case 0xea: memoryRead(); break; // NOP (implied)
case 0xeb: A() = sbc(A(), AM_Immediate()); break; // *SBC (immediate)
case 0xec: cmp(X(), AM_Absolute()); break; // CPX (absolute)
case 0xed: A() = sbc(A(), AM_Absolute()); break; // SBC (absolute)
case 0xee: busReadModifyWrite(inc(AM_Absolute())); break; // INC (absolute)
case 0xee: memoryReadModifyWrite(inc(AM_Absolute())); break; // INC (absolute)
case 0xef: isb(AM_Absolute()); break; // *ISB (absolute)
case 0xf0: branch(zero()); break; // BEQ (relative)
@ -373,15 +373,15 @@ int EightBit::MOS6502::execute() {
case 0xf3: isb(AM_IndirectIndexedY()); break; // *ISB (indirect indexed Y)
case 0xf4: AM_ZeroPageX(); break; // *NOP (zero page, X)
case 0xf5: A() = sbc(A(), AM_ZeroPageX()); break; // SBC (zero page, X)
case 0xf6: busReadModifyWrite(inc(AM_ZeroPageX())); break; // INC (zero page, X)
case 0xf6: memoryReadModifyWrite(inc(AM_ZeroPageX())); break; // INC (zero page, X)
case 0xf7: isb(AM_ZeroPageX()); break; // *ISB (zero page, X)
case 0xf8: busRead(); P() = setBit(P(), DF); break; // SED (implied)
case 0xf8: memoryRead(); P() = setBit(P(), DF); break; // SED (implied)
case 0xf9: A() = sbc(A(), AM_AbsoluteY()); break; // SBC (absolute, Y)
case 0xfa: busRead(); break; // *NOP (implied)
case 0xfa: memoryRead(); break; // *NOP (implied)
case 0xfb: isb(AM_AbsoluteY()); break; // *ISB (absolute, Y)
case 0xfc: AM_AbsoluteX(); break; // *NOP (absolute, X)
case 0xfd: A() = sbc(A(), AM_AbsoluteX()); break; // SBC (absolute, X)
case 0xfe: busReadModifyWrite(inc(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // INC (absolute, X)
case 0xfe: memoryReadModifyWrite(inc(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // INC (absolute, X)
case 0xff: isb(AM_AbsoluteX()); break; // *ISB (absolute, X)
}
@ -520,7 +520,7 @@ uint8_t EightBit::MOS6502::AM_IndirectIndexedY() {
void EightBit::MOS6502::branch(const int condition) {
const auto destination = Address_relative_byte();
if (condition) {
busRead();
memoryRead();
const auto page = PC().high;
jump(destination);
if (UNLIKELY(PC().high != page))
@ -714,32 +714,32 @@ void EightBit::MOS6502::axs(const uint8_t value) {
}
void EightBit::MOS6502::dcp(const uint8_t value) {
busReadModifyWrite(dec(value));
memoryReadModifyWrite(dec(value));
cmp(A(), BUS().DATA());
}
void EightBit::MOS6502::isb(const uint8_t value) {
busReadModifyWrite(inc(value));
memoryReadModifyWrite(inc(value));
A() = sbc(A(), BUS().DATA());
}
void EightBit::MOS6502::rla(const uint8_t value) {
busReadModifyWrite(rol(value));
memoryReadModifyWrite(rol(value));
A() = andr(A(), BUS().DATA());
}
void EightBit::MOS6502::rra(const uint8_t value) {
busReadModifyWrite(ror(value));
memoryReadModifyWrite(ror(value));
A() = adc(A(), BUS().DATA());
}
void EightBit::MOS6502::slo(const uint8_t value) {
busReadModifyWrite(asl(value));
memoryReadModifyWrite(asl(value));
A() = orr(A(), BUS().DATA());
}
void EightBit::MOS6502::sre(const uint8_t value) {
busReadModifyWrite(lsr(value));
memoryReadModifyWrite(lsr(value));
A() = eorr(A(), BUS().DATA());
}