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GB Timer: Fix some timing issues

This commit is contained in:
Jeffrey Pfau 2016-08-28 10:04:00 -07:00
parent 24bb930850
commit 70e01030d1
1 changed files with 5 additions and 5 deletions
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10
src/gb/timer.c
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@ -27,20 +27,20 @@ int32_t GBTimerProcessEvents(struct GBTimer* timer, int32_t cycles) {
timer->p->memory.io[REG_IF] |= (1 << GB_IRQ_TIMER); timer->p->memory.io[REG_IF] |= (1 << GB_IRQ_TIMER);
GBUpdateIRQs(timer->p); GBUpdateIRQs(timer->p);
timer->irqPending = false; timer->irqPending = false;
timer->nextEvent = timer->nextDiv; timer->nextEvent += timer->nextDiv;
} }
if (timer->nextDiv <= 0) { if (timer->nextDiv <= 0) {
++timer->internalDiv; ++timer->internalDiv;
timer->p->memory.io[REG_DIV] = timer->internalDiv >> 4; timer->p->memory.io[REG_DIV] = timer->internalDiv >> 4;
timer->nextDiv = GB_DMG_DIV_PERIOD; timer->nextDiv += GB_DMG_DIV_PERIOD;
timer->nextEvent = timer->nextDiv; timer->nextEvent += GB_DMG_DIV_PERIOD;
// Make sure to trigger when the correct bit is a falling edge // Make sure to trigger when the correct bit is a falling edge
if (timer->timaPeriod == 1 || (timer->internalDiv & (timer->timaPeriod - 1)) == (timer->timaPeriod >> 1) - 1) { if (timer->timaPeriod > 0 && (timer->internalDiv & (timer->timaPeriod - 1)) == timer->timaPeriod - 1) {
++timer->p->memory.io[REG_TIMA]; ++timer->p->memory.io[REG_TIMA];
if (!timer->p->memory.io[REG_TIMA]) { if (!timer->p->memory.io[REG_TIMA]) {
timer->irqPending = true; timer->irqPending = true;
timer->nextEvent = 4; timer->nextEvent += 4;
} }
} }
} }