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GBA Memory: Minor prefetch fixes

This commit is contained in:
Jeffrey Pfau 2015-06-27 14:05:37 -07:00
parent 262cbf046c
commit 2346c2355a
2 changed files with 6 additions and 4 deletions
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4
src/gba/gba.c
View File

@ -452,8 +452,8 @@ void GBATimerUpdateRegister(struct GBA* gba, int timer) {
struct GBATimer* currentTimer = &gba->timers[timer];
if (currentTimer->enable && !currentTimer->countUp) {
int32_t prefetchSkew = 0;
if ((gba->memory.lastPrefetchedPc - gba->cpu->gprs[ARM_PC]) < gba->memory.lastPrefetchedLoads * WORD_SIZE_THUMB) {
prefetchSkew = (gba->memory.lastPrefetchedPc - gba->cpu->gprs[ARM_PC]) / gba->cpu->memory.activeSeqCycles16;
if (gba->memory.lastPrefetchedPc - gba->memory.lastPrefetchedLoads * WORD_SIZE_THUMB >= (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
gba->memory.io[(REG_TM0CNT_LO + (timer << 2)) >> 1] = currentTimer->oldReload + ((gba->cpu->cycles - currentTimer->lastEvent - 2 + prefetchSkew) >> currentTimer->prescaleBits);

6
src/gba/memory.c
View File

@ -235,6 +235,8 @@ static void GBASetActiveRegion(struct ARMCore* cpu, uint32_t address) {
}
gba->lastJump = address;
memory->lastPrefetchedPc = 0;
memory->lastPrefetchedLoads = 0;
if (newRegion == memory->activeRegion && (newRegion < REGION_CART0 || (address & (SIZE_CART0 - 1)) < memory->romSize)) {
return;
}
@ -1541,10 +1543,10 @@ int32_t GBAMemoryStall(struct ARMCore* cpu, int32_t wait) {
int32_t previousLoads = 0;
// Don't prefetch too much if we're overlapping with a previous prefetch
if ((memory->lastPrefetchedPc - cpu->gprs[ARM_PC]) < memory->lastPrefetchedLoads * WORD_SIZE_THUMB) {
if (UNLIKELY((memory->lastPrefetchedPc - cpu->gprs[ARM_PC]) < memory->lastPrefetchedLoads * WORD_SIZE_THUMB)) {
previousLoads = (memory->lastPrefetchedPc - cpu->gprs[ARM_PC]) >> 1;
}
while (stall < wait && loads + previousLoads < 8) {
while (stall < wait && LIKELY(loads + previousLoads < 8)) {
stall += s;
++loads;
}