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Pass channel_1_freq_change_timing

This commit is contained in:
Lior Halphon 2019-09-30 00:09:25 +03:00
parent 0c48ecb3f8
commit ac418b9de1
1 changed files with 15 additions and 0 deletions
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15
Core/apu.c
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@ -681,6 +681,21 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
case GB_IO_NR14:
case GB_IO_NR24: {
unsigned index = reg == GB_IO_NR24? GB_SQUARE_2: GB_SQUARE_1;
/* 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]) {
/* 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].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_length &= 0xFF;
gb->apu.square_channels[index].sample_length |= (value & 7) << 8;
if (index == GB_SQUARE_1) {