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Improved emulation of the NRx2 write glitch (Zombie mode) on models prior to CGB-D

This commit is contained in:
Lior Halphon 2021-02-13 23:00:20 +02:00
parent 8ad08c1b35
commit 95051d1c1c
1 changed files with 14 additions and 3 deletions
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17
Core/apu.c
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@ -297,7 +297,7 @@ static void update_square_sample(GB_gameboy_t *gb, unsigned index)
requires the PCM12 register. The behavior implemented here was verified on *my* requires the PCM12 register. The behavior implemented here was verified on *my*
CGB, which might behave differently from other CGB revisions, as well as from the CGB, which might behave differently from other CGB revisions, as well as from the
DMG, MGB or SGB/2 */ DMG, MGB or SGB/2 */
static void nrx2_glitch(uint8_t *volume, uint8_t value, uint8_t old_value) static void _nrx2_glitch(uint8_t *volume, uint8_t value, uint8_t old_value)
{ {
if (value & 8) { if (value & 8) {
(*volume)++; (*volume)++;
@ -318,6 +318,17 @@ static void nrx2_glitch(uint8_t *volume, uint8_t value, uint8_t old_value)
(*volume) &= 0xF; (*volume) &= 0xF;
} }
static void nrx2_glitch(GB_gameboy_t *gb,uint8_t *volume, uint8_t value, uint8_t old_value)
{
if (gb->model <= GB_MODEL_CGB_C) {
_nrx2_glitch(volume, 0xFF, old_value);
_nrx2_glitch(volume, value, 0xFF);
}
else {
_nrx2_glitch(volume, value, old_value);
}
}
static void tick_square_envelope(GB_gameboy_t *gb, enum GB_CHANNELS index) static void tick_square_envelope(GB_gameboy_t *gb, enum GB_CHANNELS index)
{ {
uint8_t nrx2 = gb->io_registers[index == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22]; uint8_t nrx2 = gb->io_registers[index == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
@ -931,7 +942,7 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
update_sample(gb, index, 0, 0); update_sample(gb, index, 0, 0);
} }
else if (gb->apu.is_active[index]) { else if (gb->apu.is_active[index]) {
nrx2_glitch(&gb->apu.square_channels[index].current_volume, value, gb->io_registers[reg]); nrx2_glitch(gb, &gb->apu.square_channels[index].current_volume, value, gb->io_registers[reg]);
update_square_sample(gb, index); update_square_sample(gb, index);
} }
@ -1179,7 +1190,7 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
update_sample(gb, GB_NOISE, 0, 0); update_sample(gb, GB_NOISE, 0, 0);
} }
else if (gb->apu.is_active[GB_NOISE]) { else if (gb->apu.is_active[GB_NOISE]) {
nrx2_glitch(&gb->apu.noise_channel.current_volume, value, gb->io_registers[reg]); nrx2_glitch(gb, &gb->apu.noise_channel.current_volume, value, gb->io_registers[reg]);
update_sample(gb, GB_NOISE, update_sample(gb, GB_NOISE,
gb->apu.current_lfsr_sample ? gb->apu.current_lfsr_sample ?
gb->apu.noise_channel.current_volume : 0, gb->apu.noise_channel.current_volume : 0,