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The clock still has to tick, even while held on RDY low, otherwise cycle timing won't work.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2019-01-09 09:05:12 +00:00
parent a90ca6ba38
commit 8b187e7614
1 changed files with 13 additions and 10 deletions
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23
M6502/src/mos6502.cpp
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@ -22,18 +22,21 @@ void EightBit::MOS6502::powerOn() {
int EightBit::MOS6502::step() {
resetCycles();
ExecutingInstruction.fire(*this);
if (LIKELY(powered() && raised(RDY()))) {
if (LIKELY(powered())) {
addCycle();
if (UNLIKELY(lowered(SO())))
handleSO();
lower(SYNC()); // Instruction fetch beginning
opcode() = fetchByte();
if (UNLIKELY(lowered(RESET())))
handleRESET();
else if (UNLIKELY(lowered(NMI())))
handleNMI();
else if (UNLIKELY(lowered(IRQ()) && !interruptMasked()))
handleIRQ();
execute();
if (LIKELY(raised(RDY()))) {
lower(SYNC()); // Instruction fetch beginning
opcode() = BUS().read(PC()++); // can't use fetchByte
if (UNLIKELY(lowered(RESET())))
handleRESET();
else if (UNLIKELY(lowered(NMI())))
handleNMI();
else if (UNLIKELY(lowered(IRQ()) && !interruptMasked()))
handleIRQ();
execute();
}
}
ExecutedInstruction.fire(*this);
return cycles();