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Start adding definition of BA/BS flags.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2018-08-25 14:55:57 +01:00
parent 1212e8d4f0
commit ab78ba5db0
2 changed files with 28 additions and 1 deletions
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7
MC6809/inc/mc6809.h
View File

@ -73,6 +73,9 @@ namespace EightBit {
PinLevel& NMI() { return m_nmiLine; } // In
PinLevel& FIRQ() { return m_firqLine; } // In
PinLevel& BA() { return m_baLine; } // Out
PinLevel& BS() { return m_bsLine; } // Out
protected:
virtual void powerOn() final;
@ -125,6 +128,7 @@ namespace EightBit {
// Interrupt (etc.) handlers
void handleHALT();
void handleNMI();
void handleFIRQ();
@ -326,6 +330,9 @@ namespace EightBit {
PinLevel m_nmiLine = Low;
PinLevel m_firqLine = Low;
PinLevel m_baLine = Low;
PinLevel m_bsLine = Low;
bool m_prefix10 = false;
bool m_prefix11 = false;
};

22
MC6809/src/mc6809.cpp
View File

@ -11,6 +11,8 @@ void EightBit::mc6809::powerOn() {
Processor::powerOn();
raise(NMI());
raise(FIRQ());
lower(BA());
lower(BS());
}
int EightBit::mc6809::step() {
@ -18,7 +20,9 @@ int EightBit::mc6809::step() {
if (LIKELY(powered())) {
m_prefix10 = m_prefix11 = false;
ExecutingInstruction.fire(*this);
if (UNLIKELY(lowered(RESET())))
if (UNLIKELY(lowered(HALT())))
handleHALT();
else if (UNLIKELY(lowered(RESET())))
handleRESET();
else if (UNLIKELY(lowered(NMI())))
handleNMI();
@ -35,9 +39,16 @@ int EightBit::mc6809::step() {
// Interrupt (etc.) handlers
void EightBit::mc6809::handleHALT() {
raise(BA());
raise(BS());
}
void EightBit::mc6809::handleRESET() {
Processor::handleRESET();
raise(NMI());
lower(BA());
raise(BS());
DP() = 0;
setFlag(CC(), IF | FF); // Disable all IRQs
jump(getWordPaged(0xff, RESETvector));
@ -45,13 +56,18 @@ void EightBit::mc6809::handleRESET() {
void EightBit::mc6809::handleNMI() {
raise(NMI());
lower(BA());
raise(BS());
saveEntireRegisterState();
setFlag(CC(), IF | FF); // Disable all IRQs
jump(getWordPaged(0xff, NMIvector));
addCycles(21);
}
void EightBit::mc6809::handleIRQ() {
Processor::handleIRQ();
lower(BA());
raise(BS());
saveEntireRegisterState();
setFlag(CC(), IF); // Disable IRQ
jump(getWordPaged(0xff, IRQvector));
@ -60,6 +76,8 @@ void EightBit::mc6809::handleIRQ() {
void EightBit::mc6809::handleFIRQ() {
raise(FIRQ());
lower(BA());
raise(BS());
clearFlag(CC(), EF);
pushWordS(PC());
pushS(CC());
@ -71,6 +89,8 @@ void EightBit::mc6809::handleFIRQ() {
//
int EightBit::mc6809::execute(uint8_t opcode) {
lower(BA());
lower(BS());
if (UNLIKELY(m_prefix10))
execute10(opcode);
else if (UNLIKELY(m_prefix11))