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A bit more accurate AGB audio rendering

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This commit is contained in:
Lior Halphon 2019-10-01 18:50:59 +03:00
parent ac418b9de1
commit ca370eee7e
1 changed files with 21 additions and 2 deletions
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23
Core/apu.c
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@ -48,6 +48,23 @@ bool GB_apu_is_DAC_enabled(GB_gameboy_t *gb, unsigned index)
return false; return false;
} }
static uint8_t agb_bias_for_channel(GB_gameboy_t *gb, unsigned index)
{
if (!gb->apu.is_active[index]) return 0;
switch (index) {
case GB_SQUARE_1:
return gb->apu.square_channels[GB_SQUARE_1].current_volume;
case GB_SQUARE_2:
return gb->apu.square_channels[GB_SQUARE_2].current_volume;
case GB_WAVE:
return 0;
case GB_NOISE:
return gb->apu.noise_channel.current_volume;
}
return 0;
}
static void update_sample(GB_gameboy_t *gb, unsigned index, int8_t value, unsigned cycles_offset) static void update_sample(GB_gameboy_t *gb, unsigned index, int8_t value, unsigned cycles_offset)
{ {
if (gb->model >= GB_MODEL_AGB) { if (gb->model >= GB_MODEL_AGB) {
@ -66,15 +83,17 @@ static void update_sample(GB_gameboy_t *gb, unsigned index, int8_t value, unsign
} }
GB_sample_t output; GB_sample_t output;
uint8_t bias = agb_bias_for_channel(gb, index);
if (gb->io_registers[GB_IO_NR51] & (1 << index)) { if (gb->io_registers[GB_IO_NR51] & (1 << index)) {
output.right = (0xf - value * 2) * right_volume; output.right = (0xf - value * 2 + bias) * right_volume;
} }
else { else {
output.right = 0xf * right_volume; output.right = 0xf * right_volume;
} }
if (gb->io_registers[GB_IO_NR51] & (0x10 << index)) { if (gb->io_registers[GB_IO_NR51] & (0x10 << index)) {
output.left = (0xf - value * 2) * left_volume; output.left = (0xf - value * 2 + bias) * left_volume;
} }
else { else {
output.left = 0xf * left_volume; output.left = 0xf * left_volume;