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Correctly emulating NRx4 effects on the sound envelop of the previously playing sound. Closes #19

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This commit is contained in:
Lior Halphon 2018-01-06 12:37:45 +02:00
parent a20e8a8220
commit 0a76881eb6
1 changed files with 19 additions and 3 deletions
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22
Core/apu.c
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@ -575,6 +575,14 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + 4 - gb->apu.lf_div;
}
gb->apu.square_channels[index].current_volume = gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] >> 4;
/* The volume changes caused by NRX4 sound start take effect instantly (i.e. the effect the previously
started sound). The playback itself is not instant which is why we don't update the sample for other
cases. */
if (gb->apu.is_active[index]) {
update_square_sample(gb, index);
}
gb->apu.square_channels[index].volume_countdown = gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] & 7;
if ((gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] & 0xF8) != 0) {
@ -599,7 +607,6 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
if (!gb->apu.square_sweep_countdown) gb->apu.square_sweep_countdown = 8;
}
/* Note that we don't change the sample just yet! This was verified on hardware. */
}
/* APU glitch - if length is enabled while the DIV-divider's LSB is 1, tick the length once. */
@ -760,6 +767,17 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
}
gb->apu.noise_channel.current_volume = gb->io_registers[GB_IO_NR42] >> 4;
/* The volume changes caused by NRX4 sound start take effect instantly (i.e. the effect the previously
started sound). The playback itself is not instant which is why we don't update the sample for other
cases. */
if (gb->apu.is_active[GB_NOISE]) {
update_sample(gb, GB_NOISE,
(gb->apu.noise_channel.lfsr & 1) ?
gb->apu.noise_channel.current_volume : 0,
0);
}
gb->apu.noise_channel.volume_countdown = gb->io_registers[GB_IO_NR42] & 7;
if ((gb->io_registers[GB_IO_NR42] & 0xF8) != 0) {
@ -770,8 +788,6 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
gb->apu.noise_channel.pulse_length = 0x40;
gb->apu.noise_channel.length_enabled = false;
}
/* Note that we don't change the sample just yet! This was verified on hardware. */
}
/* APU glitch - if length is enabled while the DIV-divider's LSB is 1, tick the length once. */