Make explicit swallow operations.
This commit is contained in:
Adrian Conlon
parent
22f337569d
commit
7eca073a6e
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@ -160,6 +160,17 @@ namespace EightBit {
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memoryWrite(data);
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}
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// Unconditional page fixup cycle required
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void fixup(const register16_t address, const uint8_t unfixed_page) noexcept {
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getBytePaged(unfixed_page, address.low); // Possible fixup for page boundary crossing
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BUS().ADDRESS() = address;
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}
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// Chew up a cycle
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void swallow() noexcept { memoryRead(PC()); }
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void swallow_stack() noexcept { getBytePaged(1, S()); }
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void swallow_fetch() noexcept { fetchByte(); }
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// Instruction implementations
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[[nodiscard]] uint8_t andr(uint8_t operand, uint8_t data) noexcept;
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@ -192,12 +203,6 @@ namespace EightBit {
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void sre(uint8_t value) noexcept;
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void jam() noexcept;
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// Unconditional page fixup cycle required
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void fixup(const register16_t address, const uint8_t unfixed_page) noexcept {
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getBytePaged(unfixed_page, address.low); // Possible fixup for page boundary crossing
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BUS().ADDRESS() = address;
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}
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// Complicated addressing mode implementations
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void sta_AbsoluteX() noexcept;
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@ -128,7 +128,7 @@ int EightBit::MOS6502::execute() noexcept {
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switch (opcode()) {
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case 0x00: fetchByte(); interrupt(); break; // BRK (implied)
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case 0x00: swallow_fetch(); interrupt(); break; // BRK (implied)
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case 0x01: A() = orr(A(), AM_IndexedIndirectX()); break; // ORA (indexed indirect X)
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case 0x02: jam(); break; // *JAM
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case 0x03: slo(AM_IndexedIndirectX()); break; // *SLO (indexed indirect X)
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@ -136,11 +136,11 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x05: A() = orr(A(), AM_ZeroPage()); break; // ORA (zero page)
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case 0x06: memoryReadModifyWrite(asl(AM_ZeroPage())); break; // ASL (zero page)
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case 0x07: slo(AM_ZeroPage()); break; // *SLO (zero page)
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case 0x08: memoryRead(PC()); php(); break; // PHP (implied)
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case 0x08: swallow(); php(); break; // PHP (implied)
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case 0x09: A() = orr(A(), AM_Immediate()); break; // ORA (immediate)
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case 0x0a: memoryRead(PC()); A() = asl(A()); break; // ASL A (implied)
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case 0x0a: swallow(); A() = asl(A()); break; // ASL A (implied)
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case 0x0b: anc(AM_Immediate()); break; // *ANC (immediate)
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case 0x0c: { auto ignored = Address_Absolute(); } break; // *NOP (absolute)
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case 0x0c: { auto ignored = Address_Absolute(); } break; // *NOP (absolute)
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case 0x0d: A() = orr(A(), AM_Absolute()); break; // ORA (absolute)
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case 0x0e: memoryReadModifyWrite(asl(AM_Absolute())); break; // ASL (absolute)
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case 0x0f: slo(AM_Absolute()); break; // *SLO (absolute)
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@ -153,9 +153,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x15: A() = orr(A(), AM_ZeroPageX()); break; // ORA (zero page, X)
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case 0x16: memoryReadModifyWrite(asl(AM_ZeroPageX())); break; // ASL (zero page, X)
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case 0x17: slo(AM_ZeroPageX()); break; // *SLO (zero page, X)
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case 0x18: memoryRead(PC()); P() = clearBit(P(), CF); break; // CLC (implied)
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case 0x18: swallow(); P() = clearBit(P(), CF); break; // CLC (implied)
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case 0x19: A() = orr(A(), AM_AbsoluteY()); break; // ORA (absolute, Y)
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case 0x1a: memoryRead(PC()); break; // *NOP (implied)
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case 0x1a: swallow(); break; // *NOP (implied)
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case 0x1b: slo_AbsoluteY(); break; // *SLO (absolute, Y)
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case 0x1c: nop_AbsoluteX(); break; // *NOP (absolute, X)
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case 0x1d: A() = orr(A(), AM_AbsoluteX()); break; // ORA (absolute, X)
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@ -170,9 +170,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x25: A() = andr(A(), AM_ZeroPage()); break; // AND (zero page)
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case 0x26: memoryReadModifyWrite(rol(AM_ZeroPage())); break; // ROL (zero page)
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case 0x27: rla(AM_ZeroPage()); break; // *RLA (zero page)
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case 0x28: memoryRead(PC()); getBytePaged(1, S()); plp(); break; // PLP (implied)
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case 0x28: swallow(); swallow_stack(); plp(); break; // PLP (implied)
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case 0x29: A() = andr(A(), AM_Immediate()); break; // AND (immediate)
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case 0x2a: memoryRead(PC()); A() = rol(A()); break; // ROL A (implied)
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case 0x2a: swallow(); A() = rol(A()); break; // ROL A (implied)
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case 0x2b: anc(AM_Immediate()); break; // *ANC (immediate)
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case 0x2c: bit(A(), AM_Absolute()); break; // BIT (absolute)
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case 0x2d: A() = andr(A(), AM_Absolute()); break; // AND (absolute)
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@ -187,16 +187,16 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x35: A() = andr(A(), AM_ZeroPageX()); break; // AND (zero page, X)
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case 0x36: memoryReadModifyWrite(rol(AM_ZeroPageX())); break; // ROL (zero page, X)
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case 0x37: rla(AM_ZeroPageX()); break; // *RLA (zero page, X)
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case 0x38: memoryRead(PC()); P() = setBit(P(), CF); break; // SEC (implied)
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case 0x38: swallow(); P() = setBit(P(), CF); break; // SEC (implied)
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case 0x39: A() = andr(A(), AM_AbsoluteY()); break; // AND (absolute, Y)
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case 0x3a: memoryRead(PC()); break; // *NOP (implied)
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case 0x3a: swallow(); break; // *NOP (implied)
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case 0x3b: rla_AbsoluteY(); break; // *RLA (absolute, Y)
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case 0x3c: nop_AbsoluteX(); break; // *NOP (absolute, X)
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case 0x3d: A() = andr(A(), AM_AbsoluteX()); break; // AND (absolute, X)
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case 0x3e: memoryReadModifyWrite(rol(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // ROL (absolute, X)
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case 0x3f: rla_AbsoluteX(); break; // *RLA (absolute, X)
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case 0x40: memoryRead(PC()); rti(); break; // RTI (implied)
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case 0x40: swallow(); rti(); break; // RTI (implied)
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case 0x41: A() = eorr(A(), AM_IndexedIndirectX()); break; // EOR (indexed indirect X)
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case 0x42: jam(); break; // *JAM
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case 0x43: sre(AM_IndexedIndirectX()); break; // *SRE (indexed indirect X)
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@ -204,9 +204,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x45: A() = eorr(A(), AM_ZeroPage()); break; // EOR (zero page)
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case 0x46: memoryReadModifyWrite(lsr(AM_ZeroPage())); break; // LSR (zero page)
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case 0x47: sre(AM_ZeroPage()); break; // *SRE (zero page)
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case 0x48: memoryRead(PC()); push(A()); break; // PHA (implied)
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case 0x48: swallow(); push(A()); break; // PHA (implied)
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case 0x49: A() = eorr(A(), AM_Immediate()); break; // EOR (immediate)
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case 0x4a: memoryRead(PC()); A() = lsr(A()); break; // LSR A (implied)
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case 0x4a: swallow(); A() = lsr(A()); break; // LSR A (implied)
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case 0x4b: asr(AM_Immediate()); break; // *ASR (immediate)
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case 0x4c: jump(Address_Absolute()); break; // JMP (absolute)
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case 0x4d: A() = eorr(A(), AM_Absolute()); break; // EOR (absolute)
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@ -221,16 +221,16 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x55: A() = eorr(A(), AM_ZeroPageX()); break; // EOR (zero page, X)
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case 0x56: memoryReadModifyWrite(lsr(AM_ZeroPageX())); break; // LSR (zero page, X)
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case 0x57: sre(AM_ZeroPageX()); break; // *SRE (zero page, X)
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case 0x58: memoryRead(PC()); P() = clearBit(P(), IF); break; // CLI (implied)
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case 0x58: swallow(); P() = clearBit(P(), IF); break; // CLI (implied)
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case 0x59: A() = eorr(A(), AM_AbsoluteY()); break; // EOR (absolute, Y)
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case 0x5a: memoryRead(PC()); break; // *NOP (implied)
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case 0x5a: swallow(); break; // *NOP (implied)
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case 0x5b: sre_AbsoluteY(); break; // *SRE (absolute, Y)
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case 0x5c: nop_AbsoluteX(); break; // *NOP (absolute, X)
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case 0x5d: A() = eorr(A(), AM_AbsoluteX()); break; // EOR (absolute, X)
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case 0x5e: memoryReadModifyWrite(lsr(AM_AbsoluteX(PageCrossingBehavior::AlwaysReadTwice))); break; // LSR (absolute, X)
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case 0x5f: sre_AbsoluteX(); break; // *SRE (absolute, X)
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case 0x60: memoryRead(PC()); rts(); break; // RTS (implied)
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case 0x60: swallow(); rts(); break; // RTS (implied)
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case 0x61: A() = adc(A(), AM_IndexedIndirectX()); break; // ADC (indexed indirect X)
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case 0x62: jam(); break; // *JAM
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case 0x63: rra(AM_IndexedIndirectX()); break; // *RRA (indexed indirect X)
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@ -238,9 +238,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x65: A() = adc(A(), AM_ZeroPage()); break; // ADC (zero page)
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case 0x66: memoryReadModifyWrite(ror(AM_ZeroPage())); break; // ROR (zero page)
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case 0x67: rra(AM_ZeroPage()); break; // *RRA (zero page)
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case 0x68: memoryRead(PC()); getBytePaged(1, S()); A() = through(pop()); break; // PLA (implied)
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case 0x68: swallow(); swallow_stack(); A() = through(pop()); break; // PLA (implied)
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case 0x69: A() = adc(A(), AM_Immediate()); break; // ADC (immediate)
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case 0x6a: memoryRead(PC()); A() = ror(A()); break; // ROR A (implied)
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case 0x6a: swallow(); A() = ror(A()); break; // ROR A (implied)
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case 0x6b: arr(AM_Immediate()); break; // *ARR (immediate)
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case 0x6c: jump(Address_Indirect()); break; // JMP (indirect)
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case 0x6d: A() = adc(A(), AM_Absolute()); break; // ADC (absolute)
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@ -255,9 +255,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x75: A() = adc(A(), AM_ZeroPageX()); break; // ADC (zero page, X)
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case 0x76: memoryReadModifyWrite(ror(AM_ZeroPageX())); break; // ROR (zero page, X)
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case 0x77: rra(AM_ZeroPageX()); break; // *RRA (zero page, X)
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case 0x78: memoryRead(PC()); P() = setBit(P(), IF); break; // SEI (implied)
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case 0x78: swallow(); P() = setBit(P(), IF); break; // SEI (implied)
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case 0x79: A() = adc(A(), AM_AbsoluteY()); break; // ADC (absolute, Y)
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case 0x7a: memoryRead(PC()); break; // *NOP (implied)
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case 0x7a: swallow(); break; // *NOP (implied)
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case 0x7b: rra_AbsoluteY(); break; // *RRA (absolute, Y)
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case 0x7c: nop_AbsoluteX(); break; // *NOP (absolute, X)
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case 0x7d: A() = adc(A(), AM_AbsoluteX()); break; // ADC (absolute, X)
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@ -272,9 +272,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x85: memoryWrite(Address_ZeroPage(), A()); break; // STA (zero page)
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case 0x86: memoryWrite(Address_ZeroPage(), X()); break; // STX (zero page)
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case 0x87: memoryWrite(Address_ZeroPage(), A() & X()); break; // *SAX (zero page)
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case 0x88: memoryRead(PC()); Y() = dec(Y()); break; // DEY (implied)
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case 0x88: swallow(); Y() = dec(Y()); break; // DEY (implied)
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case 0x89: AM_Immediate(); break; // *NOP (immediate)
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case 0x8a: memoryRead(PC()); A() = through(X()); break; // TXA (implied)
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case 0x8a: swallow(); A() = through(X()); break; // TXA (implied)
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case 0x8b: A() = through((A() | 0xee) & X() & AM_Immediate()); break; // *ANE (immediate)
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case 0x8c: memoryWrite(Address_Absolute(), Y()); break; // STY (absolute)
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case 0x8d: memoryWrite(Address_Absolute(), A()); break; // STA (absolute)
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@ -289,9 +289,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0x95: memoryWrite(Address_ZeroPageX(), A()); break; // STA (zero page, X)
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case 0x96: memoryWrite(Address_ZeroPageY(), X()); break; // STX (zero page, Y)
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case 0x97: memoryWrite(Address_ZeroPageY(), A() & X()); break; // *SAX (zero page, Y)
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case 0x98: memoryRead(PC()); A() = through(Y()); break; // TYA (implied)
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case 0x98: swallow(); A() = through(Y()); break; // TYA (implied)
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case 0x99: sta_AbsoluteY(); break; // STA (absolute, Y)
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case 0x9a: memoryRead(PC()); S() = X(); break; // TXS (implied)
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case 0x9a: swallow(); S() = X(); break; // TXS (implied)
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case 0x9b: break;
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case 0x9c: sya_AbsoluteX(); break; // *SYA (absolute, X)
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case 0x9d: sta_AbsoluteX(); break; // STA (absolute, X)
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@ -306,9 +306,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0xa5: A() = through(AM_ZeroPage()); break; // LDA (zero page)
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case 0xa6: X() = through(AM_ZeroPage()); break; // LDX (zero page)
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case 0xa7: A() = X() = through(AM_ZeroPage()); break; // *LAX (zero page)
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case 0xa8: memoryRead(PC()); Y() = through(A()); break; // TAY (implied)
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case 0xa8: swallow(); Y() = through(A()); break; // TAY (implied)
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case 0xa9: A() = through(AM_Immediate()); break; // LDA (immediate)
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case 0xaa: memoryRead(PC()); X() = through(A()); break; // TAX (implied)
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case 0xaa: swallow(); X() = through(A()); break; // TAX (implied)
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case 0xab: A() = X() = through((A() | 0xee) & AM_Immediate()); break; // *ATX (immediate)
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case 0xac: Y() = through(AM_Absolute()); break; // LDY (absolute)
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case 0xad: A() = through(AM_Absolute()); break; // LDA (absolute)
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@ -323,9 +323,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0xb5: A() = through(AM_ZeroPageX()); break; // LDA (zero page, X)
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case 0xb6: X() = through(AM_ZeroPageY()); break; // LDX (zero page, Y)
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case 0xb7: A() = X() = through(AM_ZeroPageY()); break; // *LAX (zero page, Y)
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case 0xb8: memoryRead(PC()); P() = clearBit(P(), VF); break; // CLV (implied)
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case 0xb8: swallow(); P() = clearBit(P(), VF); break; // CLV (implied)
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case 0xb9: A() = through(AM_AbsoluteY()); break; // LDA (absolute, Y)
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case 0xba: memoryRead(PC()); X() = through(S()); break; // TSX (implied)
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case 0xba: swallow(); X() = through(S()); break; // TSX (implied)
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case 0xbb: break;
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case 0xbc: Y() = through(AM_AbsoluteX()); break; // LDY (absolute, X)
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case 0xbd: A() = through(AM_AbsoluteX()); break; // LDA (absolute, X)
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@ -340,9 +340,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0xc5: cmp(A(), AM_ZeroPage()); break; // CMP (zero page)
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case 0xc6: memoryReadModifyWrite(dec(AM_ZeroPage())); break; // DEC (zero page)
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case 0xc7: dcp(AM_ZeroPage()); break; // *DCP (zero page)
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case 0xc8: memoryRead(PC()); Y() = inc(Y()); break; // INY (implied)
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case 0xc8: swallow(); Y() = inc(Y()); break; // INY (implied)
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case 0xc9: cmp(A(), AM_Immediate()); break; // CMP (immediate)
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case 0xca: memoryRead(PC()); X() = dec(X()); break; // DEX (implied)
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case 0xca: swallow(); X() = dec(X()); break; // DEX (implied)
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case 0xcb: axs(AM_Immediate()); break; // *AXS (immediate)
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case 0xcc: cmp(Y(), AM_Absolute()); break; // CPY (absolute)
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case 0xcd: cmp(A(), AM_Absolute()); break; // CMP (absolute)
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@ -357,9 +357,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0xd5: cmp(A(), AM_ZeroPageX()); break; // CMP (zero page, X)
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case 0xd6: memoryReadModifyWrite(dec(AM_ZeroPageX())); break; // DEC (zero page, X)
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case 0xd7: dcp(AM_ZeroPageX()); break; // *DCP (zero page, X)
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case 0xd8: memoryRead(PC()); P() = clearBit(P(), DF); break; // CLD (implied)
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case 0xd8: swallow(); P() = clearBit(P(), DF); break; // CLD (implied)
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case 0xd9: cmp(A(), AM_AbsoluteY()); break; // CMP (absolute, Y)
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case 0xda: memoryRead(PC()); break; // *NOP (implied)
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case 0xda: swallow(); break; // *NOP (implied)
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case 0xdb: dcp_AbsoluteY(); break; // *DCP (absolute, Y)
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case 0xdc: nop_AbsoluteX(); break; // *NOP (absolute, X)
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case 0xdd: cmp(A(), AM_AbsoluteX()); break; // CMP (absolute, X)
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@ -374,9 +374,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0xe5: A() = sbc(A(), AM_ZeroPage()); break; // SBC (zero page)
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case 0xe6: memoryReadModifyWrite(inc(AM_ZeroPage())); break; // INC (zero page)
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case 0xe7: isb(AM_ZeroPage()); break; // *ISB (zero page)
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case 0xe8: memoryRead(PC()); X() = inc(X()); break; // INX (implied)
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case 0xe8: swallow(); X() = inc(X()); break; // INX (implied)
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case 0xe9: A() = sbc(A(), AM_Immediate()); break; // SBC (immediate)
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case 0xea: memoryRead(PC()); break; // NOP (implied)
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case 0xea: swallow(); break; // NOP (implied)
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case 0xeb: A() = sbc(A(), AM_Immediate()); break; // *SBC (immediate)
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case 0xec: cmp(X(), AM_Absolute()); break; // CPX (absolute)
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case 0xed: A() = sbc(A(), AM_Absolute()); break; // SBC (absolute)
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@ -391,9 +391,9 @@ int EightBit::MOS6502::execute() noexcept {
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case 0xf5: A() = sbc(A(), AM_ZeroPageX()); break; // SBC (zero page, X)
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case 0xf6: memoryReadModifyWrite(inc(AM_ZeroPageX())); break; // INC (zero page, X)
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case 0xf7: isb(AM_ZeroPageX()); break; // *ISB (zero page, X)
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case 0xf8: memoryRead(PC()); P() = setBit(P(), DF); break; // SED (implied)
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case 0xf8: swallow(); P() = setBit(P(), DF); break; // SED (implied)
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case 0xf9: A() = sbc(A(), AM_AbsoluteY()); break; // SBC (absolute, Y)
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case 0xfa: memoryRead(PC()); break; // *NOP (implied)
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case 0xfa: swallow(); break; // *NOP (implied)
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case 0xfb: isb_AbsoluteY(); break; // *ISB (absolute, Y)
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case 0xfc: nop_AbsoluteX(); break; // *NOP (absolute, X)
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case 0xfd: A() = sbc(A(), AM_AbsoluteX()); break; // SBC (absolute, X)
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@ -533,7 +533,7 @@ uint8_t EightBit::MOS6502::AM_IndirectIndexedY() noexcept {
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void EightBit::MOS6502::branch(const int condition) noexcept {
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const auto destination = Address_relative_byte();
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if (condition) {
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memoryRead(PC());
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swallow();
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const auto page = PC().high;
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jump(destination);
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if (UNLIKELY(PC().high != page))
|
||||
|
|
@ -657,7 +657,7 @@ uint8_t EightBit::MOS6502::inc(const uint8_t value) noexcept {
|
|||
|
||||
void EightBit::MOS6502::jsr() noexcept {
|
||||
const auto low = fetchByte();
|
||||
getBytePaged(1, S()); // dummy read
|
||||
swallow_stack();
|
||||
pushWord(PC());
|
||||
PC().high = fetchByte();
|
||||
PC().low = low;
|
||||
|
|
@ -695,15 +695,15 @@ uint8_t EightBit::MOS6502::ror(const uint8_t operand) noexcept {
|
|||
}
|
||||
|
||||
void EightBit::MOS6502::rti() noexcept {
|
||||
getBytePaged(1, S()); // dummy read
|
||||
swallow_stack();
|
||||
plp();
|
||||
ret();
|
||||
}
|
||||
|
||||
void EightBit::MOS6502::rts() noexcept {
|
||||
getBytePaged(1, S()); // dummy read
|
||||
swallow_stack();
|
||||
ret();
|
||||
fetchByte();
|
||||
swallow_fetch();
|
||||
}
|
||||
|
||||
// Undocumented compound instructions
|
||||
|
|
@ -784,8 +784,9 @@ void EightBit::MOS6502::sre(const uint8_t value) noexcept {
|
|||
}
|
||||
|
||||
void EightBit::MOS6502::jam() noexcept {
|
||||
memoryRead(PC());
|
||||
memoryRead(PC()--);
|
||||
swallow();
|
||||
swallow();
|
||||
--PC();
|
||||
}
|
||||
|
||||
//
|
||||
|
|
|
|||
Loading…
Reference in New Issue