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SameBoy
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More accurate emulation of the previous quirk

This commit is contained in:
Lior Halphon 2024-06-03 22:04:17 +03:00
parent 5be5bc4709
commit 322f3c7013
2 changed files with 13 additions and 5 deletions
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14
Core/apu.c
View File

@ -752,6 +752,7 @@ void GB_apu_run(GB_gameboy_t *gb, bool force)
gb->apu_output.edge_triggered[i] = true;
}
}
gb->apu.square_channels[i].just_reloaded = cycles_left == 0;
if (cycles_left) {
gb->apu.square_channels[i].sample_countdown -= cycles_left;
}
@ -1215,10 +1216,9 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
case GB_IO_NR13:
case GB_IO_NR23: {
GB_channel_t index = reg == GB_IO_NR23? GB_SQUARE_2: GB_SQUARE_1;
bool just_reloaded = gb->apu.square_channels[index].sample_countdown == (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + 1;
gb->apu.square_channels[index].sample_length &= ~0xFF;
gb->apu.square_channels[index].sample_length |= value & 0xFF;
if (just_reloaded) {
if (gb->apu.square_channels[index].just_reloaded) {
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + 1;
}
break;
@ -1247,6 +1247,9 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
uint16_t old_sample_length = gb->apu.square_channels[index].sample_length;
gb->apu.square_channels[index].sample_length &= 0xFF;
gb->apu.square_channels[index].sample_length |= (value & 7) << 8;
if (gb->apu.square_channels[index].just_reloaded) {
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + 1;
}
if (value & 0x80) {
/* Current sample index remains unchanged when restarting channels 1 or 2. It is only reset by
turning the APU off. */
@ -1268,8 +1271,7 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
else {
unsigned extra_delay = 0;
if (gb->model == GB_MODEL_CGB_E || gb->model == GB_MODEL_CGB_D) {
bool just_reloaded = gb->apu.square_channels[index].sample_countdown == (old_sample_length ^ 0x7FF) * 2 + 1;
if (!just_reloaded && !(value & 4) && !(((gb->apu.square_channels[index].sample_countdown - 1 - gb->apu.square_channels[index].delay) / 2) & 0x400)) {
if (!gb->apu.square_channels[index].just_reloaded && !(value & 4) && !(((gb->apu.square_channels[index].sample_countdown - 1 - gb->apu.square_channels[index].delay) / 2) & 0x400)) {
gb->apu.square_channels[index].current_sample_index++;
gb->apu.square_channels[index].current_sample_index &= 0x7;
gb->apu.square_channels[index].sample_surpressed = false;
@ -1383,6 +1385,10 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
case GB_IO_NR33:
gb->apu.wave_channel.sample_length &= ~0xFF;
gb->apu.wave_channel.sample_length |= value & 0xFF;
if (gb->apu.wave_channel.bugged_read_countdown == 1) { // Just reloaded countdown
/* TODO: not verified with a test ROM yet */
gb->apu.wave_channel.sample_countdown = gb->apu.wave_channel.sample_length ^ 0x7FF;
}
break;
case GB_IO_NR34:
gb->apu.wave_channel.sample_length &= 0xFF;

4
Core/apu.h
View File

@ -102,7 +102,9 @@ typedef struct
bool length_enabled; // NRX4
GB_envelope_clock_t envelope_clock;
uint8_t delay; // Hack for CGB D/E phantom step due to how sample_countdown is implemented in SameBoy
bool did_tick;
bool did_tick:1;
bool just_reloaded:1;
uint8_t padding:6;
} square_channels[2];
struct {