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GBA Memory: Fix stalling behavior a bit

This commit is contained in:
Jeffrey Pfau 2016-08-01 02:24:00 -07:00
parent 5b740518cf
commit 2d94f202a6
3 changed files with 1 additions and 4 deletions
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2
src/gba/gba.c
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@ -537,7 +537,7 @@ void GBATimerUpdateRegister(struct GBA* gba, int timer) {
struct GBATimer* currentTimer = &gba->timers[timer];
if (GBATimerFlagsIsEnable(currentTimer->flags) && !GBATimerFlagsIsCountUp(currentTimer->flags)) {
int32_t prefetchSkew = 0;
if (gba->memory.lastPrefetchedPc - gba->memory.lastPrefetchedLoads * WORD_SIZE_THUMB >= (uint32_t) gba->cpu->gprs[ARM_PC]) {
if (gba->memory.lastPrefetchedPc >= (uint32_t) gba->cpu->gprs[ARM_PC]) {
prefetchSkew = (gba->memory.lastPrefetchedPc - gba->cpu->gprs[ARM_PC]) * (gba->cpu->memory.activeSeqCycles16 + 1) / WORD_SIZE_THUMB;
}
// Reading this takes two cycles (1N+1I), so let's remove them preemptively

2
src/gba/memory.c
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@ -244,7 +244,6 @@ static void GBASetActiveRegion(struct ARMCore* cpu, uint32_t address) {
gba->lastJump = address;
memory->lastPrefetchedPc = 0;
memory->lastPrefetchedLoads = 0;
if (newRegion == memory->activeRegion) {
if (newRegion < REGION_CART0 || (address & (SIZE_CART0 - 1)) < memory->romSize) {
return;
@ -1779,7 +1778,6 @@ int32_t GBAMemoryStall(struct ARMCore* cpu, int32_t wait) {
wait -= n2s;
// TODO: Invalidate prefetch on branch
memory->lastPrefetchedLoads = loads;
memory->lastPrefetchedPc = cpu->gprs[ARM_PC] + WORD_SIZE_THUMB * loads;
// The next |loads|S waitstates disappear entirely, so long as they're all in a row

1
src/gba/memory.h
View File

@ -136,7 +136,6 @@ struct GBAMemory {
int activeRegion;
bool prefetch;
uint32_t lastPrefetchedPc;
uint32_t lastPrefetchedLoads;
uint32_t biosPrefetch;
struct GBADMA dma[4];