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Start unifying 6502 interrupt handling. NMI/IRQ/BRK are all doing mostly the same work.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2019-01-07 01:06:07 +00:00
parent b7b7c93a77
commit 06e2a5c947
2 changed files with 15 additions and 22 deletions
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3
M6502/inc/mos6502.h
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@ -71,7 +71,7 @@ namespace EightBit {
void handleSO(); void handleSO();
void handleHALT(); void handleHALT();
void interrupt(uint8_t vector); void interrupt();
virtual void push(uint8_t value) final; virtual void push(uint8_t value) final;
virtual uint8_t pop() final; virtual uint8_t pop() final;
@ -144,7 +144,6 @@ namespace EightBit {
uint8_t andr(uint8_t operand, uint8_t data); uint8_t andr(uint8_t operand, uint8_t data);
uint8_t asl(uint8_t value); uint8_t asl(uint8_t value);
void bit(uint8_t operand, uint8_t data); void bit(uint8_t operand, uint8_t data);
void brk();
void cmp(uint8_t first, uint8_t second); void cmp(uint8_t first, uint8_t second);
uint8_t dec(uint8_t value); uint8_t dec(uint8_t value);
uint8_t eorr(uint8_t operand, uint8_t data); uint8_t eorr(uint8_t operand, uint8_t data);

34
M6502/src/mos6502.cpp
View File

@ -48,34 +48,35 @@ void EightBit::MOS6502::handleSO() {
void EightBit::MOS6502::handleHALT() { void EightBit::MOS6502::handleHALT() {
Processor::execute(0xea); // NOP Processor::execute(0xea); // NOP
addCycles(2);
} }
void EightBit::MOS6502::handleRESET() { void EightBit::MOS6502::handleRESET() {
LittleEndianProcessor::handleRESET();
jump(getWordPaged(0xff, RSTvector)); jump(getWordPaged(0xff, RSTvector));
addCycles(4); // ?? TBC raise(RESET());
} }
void EightBit::MOS6502::handleNMI() { void EightBit::MOS6502::handleNMI() {
raise(HALT());
interrupt();
raise(NMI()); raise(NMI());
interrupt(NMIvector);
addCycles(4); // ?? TBC
} }
void EightBit::MOS6502::handleIRQ() { void EightBit::MOS6502::handleIRQ() {
LittleEndianProcessor::handleIRQ(); raise(HALT());
interrupt(IRQvector); interrupt();
addCycles(4); // ?? TBC raise(INT());
} }
void EightBit::MOS6502::interrupt(uint8_t vector) { void EightBit::MOS6502::interrupt() {
raise(HALT()); const bool nmi = lowered(NMI());
const bool irq = lowered(IRQ());
const bool hardware = nmi || irq;
const bool software = !hardware;
pushWord(PC()); pushWord(PC());
push(P()); push(P() | (software ? BF : 0));
setFlag(P(), IF); // Disable IRQ setFlag(P(), IF); // Disable IRQ
jump(getWordPaged(0xff, vector)); jump(getWordPaged(0xff, nmi ? NMIvector : IRQvector));
} }
// //
@ -96,7 +97,7 @@ int EightBit::MOS6502::execute() {
switch (opcode()) { switch (opcode()) {
case 0x00: fetchByte(); brk(); break; // BRK (implied) case 0x00: fetchByte(); interrupt(); break; // BRK (implied)
case 0x01: A() = orr(A(), AM_IndexedIndirectX()); break; // ORA (indexed indirect X) case 0x01: A() = orr(A(), AM_IndexedIndirectX()); break; // ORA (indexed indirect X)
case 0x02: break; case 0x02: break;
case 0x03: slo(AM_IndexedIndirectX()); break; // *SLO (indexed indirect X) case 0x03: slo(AM_IndexedIndirectX()); break; // *SLO (indexed indirect X)
@ -598,13 +599,6 @@ void EightBit::MOS6502::bit(const uint8_t operand, const uint8_t data) {
adjustNegative(data); adjustNegative(data);
} }
void EightBit::MOS6502::brk() {
pushWord(PC());
php();
setFlag(P(), IF);
jump(getWordPaged(0xff, IRQvector));
}
void EightBit::MOS6502::cmp(const uint8_t first, const uint8_t second) { void EightBit::MOS6502::cmp(const uint8_t first, const uint8_t second) {
const register16_t result = first - second; const register16_t result = first - second;
adjustNZ(result.low); adjustNZ(result.low);