From 815c99710aab2b74214cddf50d15c9e21dfa6c94 Mon Sep 17 00:00:00 2001 From: Adrian Conlon Date: Sat, 29 Dec 2018 22:22:31 +0000 Subject: [PATCH] Add enough undocumented 6502 instructions to get through "nestest". Signed-off-by: Adrian Conlon --- M6502/inc/mos6502.h | 9 +++ M6502/src/mos6502.cpp | 184 +++++++++++++++++++++++++----------------- 2 files changed, 117 insertions(+), 76 deletions(-) diff --git a/M6502/inc/mos6502.h b/M6502/inc/mos6502.h index 289de12..f4e6141 100644 --- a/M6502/inc/mos6502.h +++ b/M6502/inc/mos6502.h @@ -166,6 +166,15 @@ namespace EightBit { void rti(); void rts(); + // Undocumented compound instructions + + void dcp(uint8_t value); + void isb(uint8_t value); + void rla(uint8_t value); + void rra(uint8_t value); + void slo(uint8_t value); + void sre(uint8_t value); + uint8_t x = 0; // index register X uint8_t y = 0; // index register Y uint8_t a = 0; // accumulator diff --git a/M6502/src/mos6502.cpp b/M6502/src/mos6502.cpp index c920c37..af4f305 100644 --- a/M6502/src/mos6502.cpp +++ b/M6502/src/mos6502.cpp @@ -99,45 +99,45 @@ int EightBit::MOS6502::execute() { case 0x00: brk(); break; // BRK case 0x01: addCycle(); A() = orr(A(), AM_IndexedIndirectX()); break; // ORA (indexed indirect X) case 0x02: break; - case 0x03: break; - case 0x04: break; + case 0x03: addCycles(2); 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: addCycle(); Processor::busWrite(asl(AM_ZeroPage())); break; // ASL (zero page) - case 0x07: break; + case 0x07: addCycle(); slo(AM_ZeroPage()); break; // *SLO (zero page) case 0x08: addCycle(); php(); break; // PHP case 0x09: A() = orr(A(), AM_Immediate()); break; // ORA (immediate) case 0x0a: addCycle(); A() = asl(A()); break; // ASL A case 0x0b: break; - case 0x0c: break; + case 0x0c: AM_Absolute(); break; // *NOP (absolute) case 0x0d: A() = orr(A(), AM_Absolute()); break; // ORA (absolute) case 0x0e: addCycle(); Processor::busWrite(asl(AM_Absolute())); break; // ASL (absolute) - case 0x0f: break; + case 0x0f: addCycle(); slo(AM_Absolute()); break; // *SLO (absolute) case 0x10: branch(!negative()); break; // BPL (relative) case 0x11: A() = orr(A(), AM_IndirectIndexedY()); break; // ORA (indirect indexed Y) case 0x12: break; - case 0x13: break; - case 0x14: break; + case 0x13: addCycle(); slo(AM_IndirectIndexedY()); break; // *SLO (indirect indexed Y) + case 0x14: addCycle(); AM_ZeroPageX(); break; // *NOP (zero page, X) case 0x15: addCycle(); A() = orr(A(), AM_ZeroPageX()); break; // ORA (zero page, X) case 0x16: addCycles(2); Processor::busWrite(asl(AM_ZeroPageX())); break; // ASL (zero page, X) - case 0x17: break; + case 0x17: addCycles(2); slo(AM_ZeroPageX()); break; // *SLO (zero page, X) case 0x18: addCycle(); clearFlag(P(), CF); break; // CLC case 0x19: A() = orr(A(), AM_AbsoluteY()); break; // ORA (absolute, Y) - case 0x1a: break; - case 0x1b: break; - case 0x1c: break; + case 0x1a: addCycle(); break; // *NOP (implied) + case 0x1b: addCycle(); 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: addCycles(2); Processor::busWrite(asl(AM_AbsoluteX())); break; // ASL (absolute, X) - case 0x1f: break; + case 0x1f: addCycle(); slo(AM_AbsoluteX()); break; // *SLO (absolute, X) case 0x20: addCycle(); jsr(Address_Absolute()); break; // JSR (absolute) case 0x21: addCycle(); A() = andr(A(), AM_IndexedIndirectX()); break; // AND (indexed indirect X) case 0x22: break; - case 0x23: break; + case 0x23: addCycles(2); 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: addCycle(); Processor::busWrite(rol(AM_ZeroPage())); break; // ROL (zero page) - case 0x27: break; + case 0x27: addCycle(); rla(AM_ZeroPage()); break; // *RLA (zero page) case 0x28: addCycles(2); plp(); break; // PLP case 0x29: A() = andr(A(), AM_Immediate()); break; // AND (immediate) case 0x2a: addCycle(); A() = rol(A()); break; // ROL A @@ -145,33 +145,33 @@ int EightBit::MOS6502::execute() { case 0x2c: bit(A(), AM_Absolute()); break; // BIT (absolute) case 0x2d: A() = andr(A(), AM_Absolute()); break; // AND (absolute) case 0x2e: addCycle(); Processor::busWrite(rol(AM_Absolute())); break; // ROL (absolute) - case 0x2f: break; + case 0x2f: addCycle(); rla(AM_Absolute()); break; // *RLA (absolute) case 0x30: branch(negative()); break; // BMI case 0x31: A() = andr(A(), AM_IndirectIndexedY()); break; // AND (indirect indexed Y) case 0x32: break; - case 0x33: break; - case 0x34: break; + case 0x33: addCycle(); rla(AM_IndirectIndexedY()); break; // *RLA (indirect indexed Y) + case 0x34: addCycle(); AM_ZeroPageX(); break; // *NOP (zero page, X) case 0x35: addCycle(); A() = andr(A(), AM_ZeroPageX()); break; // AND (zero page, X) case 0x36: addCycles(2); Processor::busWrite(rol(AM_ZeroPageX())); break; // ROL (zero page, X) - case 0x37: break; + case 0x37: addCycles(2); rla(AM_ZeroPageX()); break; // *RLA (zero page, X) case 0x38: addCycle(); setFlag(P(), CF); break; // SEC case 0x39: A() = andr(A(), AM_AbsoluteY()); break; // AND (absolute, Y) - case 0x3a: break; - case 0x3b: break; - case 0x3c: break; + case 0x3a: addCycle(); break; // *NOP (implied) + case 0x3b: addCycle(); 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: addCycles(2); Processor::busWrite(rol(AM_AbsoluteX())); break; // ROL (absolute, X) - case 0x3f: break; + case 0x3f: addCycle(); rla(AM_AbsoluteX()); break; // *RLA (absolute, X) case 0x40: addCycles(2); rti(); break; // RTI case 0x41: addCycle(); A() = eorr(A(), AM_IndexedIndirectX()); break; // EOR (indexed indirect X) case 0x42: break; - case 0x43: break; - case 0x44: break; + case 0x43: addCycles(2); 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: addCycle(); Processor::busWrite(lsr(AM_ZeroPage())); break; // LSR (zero page) - case 0x47: break; + case 0x47: addCycle(); sre(AM_ZeroPage()); break; // *SRE (zero page) case 0x48: addCycle(); push(A()); break; // PHA case 0x49: A() = eorr(A(), AM_Immediate()); break; // EOR (immediate) case 0x4a: addCycle(); A() = lsr(A()); break; // LSR A @@ -179,33 +179,33 @@ int EightBit::MOS6502::execute() { case 0x4c: jump(Address_Absolute()); break; // JMP (absolute) case 0x4d: A() = eorr(A(), AM_Absolute()); break; // EOR (absolute) case 0x4e: addCycle(); Processor::busWrite(lsr(AM_Absolute())); break; // LSR (absolute) - case 0x4f: break; + case 0x4f: addCycle(); sre(AM_Absolute()); break; // *SRE (absolute) case 0x50: branch(!overflow()); break; // BVC (relative) case 0x51: A() = eorr(A(), AM_IndirectIndexedY()); break; // EOR (indirect indexed Y) case 0x52: break; - case 0x53: break; - case 0x54: break; + case 0x53: addCycle(); sre(AM_IndirectIndexedY()); break; // *SRE (indirect indexed Y) + case 0x54: addCycle(); AM_ZeroPageX(); break; // *NOP (zero page, X) case 0x55: addCycle(); A() = eorr(A(), AM_ZeroPageX()); break; // EOR (zero page, X) case 0x56: addCycles(2); Processor::busWrite(lsr(AM_ZeroPageX())); break; // LSR (zero page, X) - case 0x57: break; + case 0x57: addCycles(2); sre(AM_ZeroPageX()); break; // *SRE (zero page, X) case 0x58: addCycle(); clearFlag(P(), IF); break; // CLI case 0x59: A() = eorr(A(), AM_AbsoluteY()); break; // EOR (absolute, Y) - case 0x5a: break; - case 0x5b: break; - case 0x5c: break; + case 0x5a: addCycle(); break; // *NOP (implied) + case 0x5b: addCycle(); 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: addCycles(2); Processor::busWrite(lsr(AM_AbsoluteX())); break; // LSR (absolute, X) - case 0x5f: break; + case 0x5f: addCycle(); sre(AM_AbsoluteX()); break; // *SRE (absolute, X) case 0x60: addCycles(3); rts(); break; // RTS case 0x61: addCycle(); A() = adc(A(), AM_IndexedIndirectX()); break; // ADC (indexed indirect X) case 0x62: break; - case 0x63: break; - case 0x64: break; + case 0x63: addCycles(2); 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: addCycle(); Processor::busWrite(ror(AM_ZeroPage())); break; // ROR (zero page) - case 0x67: break; + case 0x67: addCycle(); rra(AM_ZeroPage()); break; // *RRA (zero page) case 0x68: addCycles(2); A() = through(pop()); break; // PLA case 0x69: A() = adc(A(), AM_Immediate()); break; // ADC (immediate) case 0x6a: addCycle(); A() = ror(A()); break; // ROR A @@ -213,33 +213,33 @@ int EightBit::MOS6502::execute() { case 0x6c: jump(Address_Indirect()); break; // JMP (indirect) case 0x6d: A() = adc(A(), AM_Absolute()); break; // ADC (absolute) case 0x6e: addCycle(); Processor::busWrite(ror(AM_Absolute())); break; // ROR (absolute) - case 0x6f: break; + case 0x6f: addCycle(); rra(AM_Absolute()); break; // *RRA (absolute) case 0x70: branch(overflow()); break; // BVS (relative) case 0x71: A() = adc(A(), AM_IndirectIndexedY()); break; // ADC (indirect indexed Y) case 0x72: break; - case 0x73: break; - case 0x74: break; + case 0x73: addCycle(); rra(AM_IndirectIndexedY()); break; // *RRA (indirect indexed Y) + case 0x74: addCycle(); AM_ZeroPageX(); break; // *NOP (zero page, X) case 0x75: addCycle(); A() = adc(A(), AM_ZeroPageX()); break; // ADC (zero page, X) case 0x76: addCycles(2); Processor::busWrite(ror(AM_ZeroPageX())); break; // ROR (zero page, X) - case 0x77: break; + case 0x77: addCycles(2); rra(AM_ZeroPageX()); break; // *RRA (zero page, X) case 0x78: addCycle(); setFlag(P(), IF); break; // SEI case 0x79: A() = adc(A(), AM_AbsoluteY()); break; // ADC (absolute, Y) - case 0x7a: break; - case 0x7b: break; - case 0x7c: break; + case 0x7a: addCycle(); break; // *NOP (implied) + case 0x7b: addCycle(); 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: addCycles(2); Processor::busWrite(ror(AM_AbsoluteX())); break; // ROR (absolute, X) - case 0x7f: break; + case 0x7f: addCycle(); rra(AM_AbsoluteX()); break; // *RRA (absolute, X) - case 0x80: break; + case 0x80: AM_Immediate(); break; // *NOP (immediate) case 0x81: addCycle(); Processor::busWrite(Address_IndexedIndirectX(), A()); break; // STA (indexed indirect X) case 0x82: break; - case 0x83: break; + case 0x83: addCycle(); Processor::busWrite(Address_IndexedIndirectX(), A() & X()); break; // *SAX (indexed indirect X) case 0x84: Processor::busWrite(Address_ZeroPage(), Y()); break; // STY (zero page) case 0x85: Processor::busWrite(Address_ZeroPage(), A()); break; // STA (zero page) case 0x86: Processor::busWrite(Address_ZeroPage(), X()); break; // STX (zero page) - case 0x87: break; + case 0x87: Processor::busWrite(Address_ZeroPage(), A() & X()); break; // *SAX (zero page) case 0x88: addCycle(); Y() = dec(Y()); break; // DEY case 0x89: break; case 0x8a: addCycle(); A() = through(X()); break; // TXA @@ -247,7 +247,7 @@ int EightBit::MOS6502::execute() { case 0x8c: Processor::busWrite(Address_Absolute(), Y()); break; // STY (absolute) case 0x8d: Processor::busWrite(Address_Absolute(), A()); break; // STA (absolute) case 0x8e: Processor::busWrite(Address_Absolute(), X()); break; // STX (absolute) - case 0x8f: break; + case 0x8f: Processor::busWrite(Address_Absolute(), A() & X()); break; // *SAX (absolute) case 0x90: branch(!carry()); break; // BCC case 0x91: addCycle(); Processor::busWrite(Address_IndirectIndexedY().first, A()); break; // STA (indirect indexed Y) @@ -256,7 +256,7 @@ int EightBit::MOS6502::execute() { case 0x94: addCycle(); Processor::busWrite(Address_ZeroPageX(), Y()); break; // STY (zero page, X) case 0x95: addCycle(); Processor::busWrite(Address_ZeroPageX(), A()); break; // STA (zero page, X) case 0x96: addCycle(); Processor::busWrite(Address_ZeroPageY(), X()); break; // STX (zero page, Y) - case 0x97: break; + case 0x97: addCycle(); Processor::busWrite(Address_ZeroPageY(), A() & X()); break; // *SAX (zero page, Y) case 0x98: addCycle(); A() = through(Y()); break; // TYA case 0x99: addCycle(); Processor::busWrite(Address_AbsoluteY().first, A()); break; // STA (absolute, Y) case 0x9a: addCycle(); S() = X(); break; // TXS @@ -269,11 +269,11 @@ int EightBit::MOS6502::execute() { case 0xa0: Y() = through(AM_Immediate()); break; // LDY (immediate) case 0xa1: addCycle(); A() = through(AM_IndexedIndirectX()); break; // LDA (indexed indirect X) case 0xa2: X() = through(AM_Immediate()); break; // LDX (immediate) - case 0xa3: break; + case 0xa3: addCycle(); A() = X() = through(AM_IndexedIndirectX()); break; // *LAX (indexed indirect X) case 0xa4: Y() = through(AM_ZeroPage()); break; // LDY (zero page) case 0xa5: A() = through(AM_ZeroPage()); break; // LDA (zero page) case 0xa6: X() = through(AM_ZeroPage()); break; // LDX (zero page) - case 0xa7: break; + case 0xa7: A() = X() = through(AM_ZeroPage()); break; // *LAX (zero page) case 0xa8: addCycle(); Y() = through(A()); break; // TAY case 0xa9: A() = through(AM_Immediate()); break; // LDA (immediate) case 0xaa: addCycle(); X() = through(A()); break; // TAX @@ -281,16 +281,16 @@ int EightBit::MOS6502::execute() { case 0xac: Y() = through(AM_Absolute()); break; // LDY (absolute) case 0xad: A() = through(AM_Absolute()); break; // LDA (absolute) case 0xae: X() = through(AM_Absolute()); break; // LDX (absolute) - case 0xaf: break; + case 0xaf: A() = X() = through(AM_Absolute()); break; // *LAX (absolute) case 0xb0: branch(carry()); break; // BCS case 0xb1: A() = through(AM_IndirectIndexedY()); break; // LDA (indirect indexed Y) case 0xb2: break; - case 0xb3: break; + case 0xb3: A() = X() = through(AM_IndirectIndexedY()); break; // *LAX (indirect indexed Y) case 0xb4: addCycle(); Y() = through(AM_ZeroPageX()); break; // LDY (zero page, X) case 0xb5: addCycle(); A() = through(AM_ZeroPageX()); break; // LDA (zero page, X) case 0xb6: addCycle(); X() = through(AM_ZeroPageY()); break; // LDX (zero page, Y) - case 0xb7: break; + case 0xb7: addCycle(); A() = X() = through(AM_ZeroPageY()); break; // *LAX (zero page, Y) case 0xb8: addCycle(); clearFlag(P(), VF); break; // CLV case 0xb9: A() = through(AM_AbsoluteY()); break; // LDA (absolute, Y) case 0xba: addCycle(); X() = through(S()); break; // TSX @@ -298,16 +298,16 @@ int EightBit::MOS6502::execute() { case 0xbc: Y() = through(AM_AbsoluteX()); break; // LDY (absolute, X) case 0xbd: A() = through(AM_AbsoluteX()); break; // LDA (absolute, X) case 0xbe: X() = through(AM_AbsoluteY()); break; // LDX (absolute, Y) - case 0xbf: break; + case 0xbf: A() = X() = through(AM_AbsoluteY()); break; // *LAX (absolute, Y) case 0xc0: cmp(Y(), AM_Immediate()); break; // CPY (immediate) case 0xc1: addCycle(); cmp(A(), AM_IndexedIndirectX()); break; // CMP (indexed indirect X) case 0xc2: break; - case 0xc3: break; + case 0xc3: addCycles(2); 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: addCycle(); Processor::busWrite(dec(AM_ZeroPage())); break; // DEC (zero page) - case 0xc7: break; + case 0xc7: addCycle(); dcp(AM_ZeroPage()); break; // *DCP (zero page) case 0xc8: addCycle(); Y() = inc(Y()); break; // INY case 0xc9: cmp(A(), AM_Immediate()); break; // CMP (immediate) case 0xca: addCycle(); X() = dec(X()); break; // DEX @@ -315,58 +315,58 @@ int EightBit::MOS6502::execute() { case 0xcc: cmp(Y(), AM_Absolute()); break; // CPY (absolute) case 0xcd: cmp(A(), AM_Absolute()); break; // CMP (absolute) case 0xce: addCycle(); Processor::busWrite(dec(AM_Absolute())); break; // DEC (absolute) - case 0xcf: break; + case 0xcf: addCycle(); dcp(AM_Absolute()); break; // *DCP (absolute) case 0xd0: branch(!zero()); break; // BNE case 0xd1: cmp(A(), AM_IndirectIndexedY()); break; // CMP (indirect indexed Y) case 0xd2: break; - case 0xd3: break; - case 0xd4: break; + case 0xd3: addCycle(); dcp(AM_IndirectIndexedY()); break; // *DCP (indirect indexed Y) + case 0xd4: addCycle(); AM_ZeroPageX(); break; // *NOP (zero page, X) case 0xd5: addCycle(); cmp(A(), AM_ZeroPageX()); break; // CMP (zero page, X) case 0xd6: addCycles(2); Processor::busWrite(dec(AM_ZeroPageX())); break; // DEC (zero page, X) - case 0xd7: break; + case 0xd7: addCycles(2); dcp(AM_ZeroPageX()); break; // *DCP (zero page, X) case 0xd8: addCycle(); clearFlag(P(), DF); break; // CLD case 0xd9: cmp(A(), AM_AbsoluteY()); break; // CMP (absolute, Y) - case 0xda: break; - case 0xdb: break; - case 0xdc: break; + case 0xda: addCycle(); break; // *NOP (implied) + case 0xdb: addCycle(); 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: addCycles(2); Processor::busWrite(dec(AM_AbsoluteX())); break; // DEC (absolute, X) - case 0xdf: break; + case 0xdf: addCycle(); dcp(AM_AbsoluteX()); break; // *DCP (absolute, X) case 0xe0: cmp(X(), AM_Immediate()); break; // CPX (immediate) case 0xe1: addCycle(); A() = sbc(A(), AM_IndexedIndirectX()); break; // SBC (indexed indirect X) case 0xe2: break; - case 0xe3: break; + case 0xe3: addCycles(2); 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: addCycle(); Processor::busWrite(inc(AM_ZeroPage())); break; // INC (zero page) - case 0xe7: break; + case 0xe7: addCycle(); isb(AM_ZeroPage()); break; // *ISB (zero page) case 0xe8: addCycle(); X() = inc(X()); break; // INX case 0xe9: A() = sbc(A(), AM_Immediate()); break; // SBC (immediate) case 0xea: addCycle(); break; // NOP - case 0xeb: break; + 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: addCycle(); Processor::busWrite(inc(AM_Absolute())); break; // INC (absolute) - case 0xef: break; + case 0xef: addCycle(); isb(AM_Absolute()); break; // *ISB (absolute) case 0xf0: branch(zero()); break; // BEQ case 0xf1: A() = sbc(A(), AM_IndirectIndexedY()); break; // SBC (indirect indexed Y) case 0xf2: break; - case 0xf3: break; - case 0xf4: break; + case 0xf3: addCycle(); isb(AM_IndirectIndexedY()); break; // *ISB (indirect indexed Y) + case 0xf4: addCycle(); AM_ZeroPageX(); break; // *NOP (zero page, X) case 0xf5: addCycle(); A() = sbc(A(), AM_ZeroPageX()); break; // SBC (zero page, X) case 0xf6: addCycles(2); Processor::busWrite(inc(AM_ZeroPageX())); break; // INC (zero page, X) - case 0xf7: break; + case 0xf7: addCycles(2); isb(AM_ZeroPageX()); break; // *ISB (zero page, X) case 0xf8: addCycle(); setFlag(P(), DF); break; // SED case 0xf9: A() = sbc(A(), AM_AbsoluteY()); break; // SBC (absolute, Y) - case 0xfa: break; - case 0xfb: break; - case 0xfc: break; + case 0xfa: addCycle(); break; // *NOP (implied) + case 0xfb: addCycle(); 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: addCycles(2); Processor::busWrite(inc(AM_AbsoluteX())); break; // INC (absolute, X) - case 0xff: break; + case 0xff: addCycle(); isb(AM_AbsoluteX()); break; // *ISB (absolute, X) } ASSUME(cycles() > 0); @@ -648,3 +648,35 @@ void EightBit::MOS6502::rts() { ret(); ++PC(); } + +// Undocumented compound instructions + +void EightBit::MOS6502::dcp(const uint8_t value) { + Processor::busWrite(dec(value)); + cmp(A(), BUS().DATA()); +} + +void EightBit::MOS6502::isb(const uint8_t value) { + Processor::busWrite(inc(value)); + A() = sbc(A(), BUS().DATA()); +} + +void EightBit::MOS6502::rla(const uint8_t value) { + Processor::busWrite(rol(value)); + A() = andr(A(), BUS().DATA()); +} + +void EightBit::MOS6502::rra(const uint8_t value) { + Processor::busWrite(ror(value)); + A() = adc(A(), BUS().DATA()); +} + +void EightBit::MOS6502::slo(const uint8_t value) { + Processor::busWrite(asl(value)); + A() = orr(A(), BUS().DATA()); +} + +void EightBit::MOS6502::sre(const uint8_t value) { + Processor::busWrite(lsr(value)); + A() = eorr(A(), BUS().DATA()); +}