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More accurate sample repeat glitch, fixes #483

This commit is contained in:
Lior Halphon 2022-08-14 17:43:28 +03:00
parent 95773b9538
commit 9bf7e0b4df
1 changed files with 4 additions and 17 deletions
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21
Core/apu.c
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@ -1111,19 +1111,6 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
case GB_IO_NR13:
case GB_IO_NR23: {
unsigned index = reg == GB_IO_NR23? GB_SQUARE_2: GB_SQUARE_1;
if (gb->apu.is_active[index]) {
/* On an AGB, as well as on CGB C and earlier (TODO: Tested: 0, B and C), it behaves slightly different on
double speed. */
if (gb->model == GB_MODEL_CGB_E || gb->model == GB_MODEL_CGB_D || gb->apu.square_channels[index].sample_countdown & 1) {
if (gb->apu.square_channels[index].did_tick &&
gb->apu.square_channels[index].sample_countdown >> 1 == (gb->apu.square_channels[index].sample_length ^ 0x7FF)) {
gb->apu.square_channels[index].current_sample_index--;
gb->apu.square_channels[index].current_sample_index &= 7;
gb->apu.square_channels[index].sample_surpressed = false;
}
}
}
gb->apu.square_channels[index].sample_length &= ~0xFF;
gb->apu.square_channels[index].sample_length |= value & 0xFF;
break;
@ -1133,10 +1120,10 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
case GB_IO_NR24: {
unsigned index = reg == GB_IO_NR24? GB_SQUARE_2: GB_SQUARE_1;
bool was_active = gb->apu.is_active[index];
/* TODO: When the sample length changes right before being updated, the countdown should change to the
old length, but the current sample should not change. Because our write timing isn't accurate to
the T-cycle, we hack around it by stepping the sample index backwards. */
if ((value & 0x80) == 0 && gb->apu.is_active[index]) {
/* TODO: When the sample length changes right before being updated from ≥$700 to <$700, the countdown
should change to the old length, but the current sample should not change. Because our write
timing isn't accurate to the T-cycle, we hack around it by stepping the sample index backwards. */
if ((value & 0x80) == 0 && gb->apu.is_active[index] && (gb->io_registers[reg] & 0x7) == 7 && (value & 7) != 7) {
/* On an AGB, as well as on CGB C and earlier (TODO: Tested: 0, B and C), it behaves slightly different on
double speed. */
if (gb->model == GB_MODEL_CGB_E || gb->model == GB_MODEL_CGB_D || gb->apu.square_channels[index].sample_countdown & 1) {