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GBA: Fix timing of reading from timer registers

This commit is contained in:
Jeffrey Pfau 2015-06-22 22:32:46 -07:00
parent 9cc4c9e43d
commit a85ae6563c
2 changed files with 3 additions and 1 deletions
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1
CHANGES
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@ -48,6 +48,7 @@ Bugfixes:
- GBA Video: Fix windows not affecting sprites
- VFS: Fix line-reading to return proper values
- GBA Memory: Fix load/store multiple video memory waitstates
- GBA: Fix timing of reading from timer registers
Misc:
- Qt: Handle saving input settings better
- Debugger: Free watchpoints in addition to breakpoints

3
src/gba/gba.c
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@ -451,7 +451,8 @@ void GBAApplyPatch(struct GBA* gba, struct Patch* patch) {
void GBATimerUpdateRegister(struct GBA* gba, int timer) {
struct GBATimer* currentTimer = &gba->timers[timer];
if (currentTimer->enable && !currentTimer->countUp) {
gba->memory.io[(REG_TM0CNT_LO + (timer << 2)) >> 1] = currentTimer->oldReload + ((gba->cpu->cycles - currentTimer->lastEvent) >> currentTimer->prescaleBits);
// Reading this takes two cycles (1N+1I), so let's remove them preemptively
gba->memory.io[(REG_TM0CNT_LO + (timer << 2)) >> 1] = currentTimer->oldReload + ((gba->cpu->cycles - currentTimer->lastEvent - 2) >> currentTimer->prescaleBits);
}
}