diff --git a/CHANGES b/CHANGES index 255c5aca2..cb24f5ed0 100644 --- a/CHANGES +++ b/CHANGES @@ -92,7 +92,6 @@ Emulation fixes: - ARM: Fix stepping when events are pending - GBA DMA: Fix case where DMAs could get misaligned (fixes mgba.io/i/1092) - GBA Memory: Fix open bus from IWRAM (fixes mgba.io/i/1575) - - GBA Memory: Improve gamepak prefetch timing - GBA Timers: Improve timer startup emulation - GBA Video: Fix OpenGL renderer 512x512 backgrounds (fixes mgba.io/i/1572) - GBA Video: Fix BLDY for semitransparent sprite on non-target-2 backgrounds diff --git a/src/gba/memory.c b/src/gba/memory.c index 10cdd777c..091bfa1e1 100644 --- a/src/gba/memory.c +++ b/src/gba/memory.c @@ -1622,19 +1622,17 @@ int32_t GBAMemoryStall(struct ARMCore* cpu, int32_t wait) { maxLoads -= previousLoads; } - int32_t s = cpu->memory.activeSeqCycles16; + int32_t s = cpu->memory.activeSeqCycles16 + 1; int32_t n2s = cpu->memory.activeNonseqCycles16 - cpu->memory.activeSeqCycles16 + 1; // Figure out how many sequential loads we can jam in - int32_t stall = s + 1; + int32_t stall = s; int32_t loads = 1; while (stall < wait && loads < maxLoads) { stall += s; ++loads; } - memory->lastPrefetchedPc = cpu->gprs[ARM_PC] + WORD_SIZE_THUMB * (loads + previousLoads - 1); - if (stall > wait) { // The wait cannot take less time than the prefetch stalls wait = stall; @@ -1643,9 +1641,10 @@ int32_t GBAMemoryStall(struct ARMCore* cpu, int32_t wait) { // This instruction used to have an N, convert it to an S. wait -= n2s; - // The next |loads|S waitstates disappear entirely, so long as they're all in a row - wait -= stall - 1; + memory->lastPrefetchedPc = cpu->gprs[ARM_PC] + WORD_SIZE_THUMB * (loads + previousLoads - 1); + // The next |loads|S waitstates disappear entirely, so long as they're all in a row + cpu->cycles -= (s - 1) * loads; return wait; }