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Fix skipped square tick when writing to NR13/23, fixes Telefang start screen audio on CGB-D and E

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This commit is contained in:
Lior Halphon 2022-03-12 15:38:05 +02:00
parent b5e271386a
commit 9fe965bcc2
1 changed files with 13 additions and 0 deletions
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13
Core/apu.c
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@ -1093,6 +1093,19 @@ 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;