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In DMG mode, the length registers are not affected by turning the APU on and off. Why? Why not!

This commit is contained in:
Lior Halphon 2017-08-11 22:23:03 +03:00
parent 0e22ad8eb1
commit 066efab985
2 changed files with 26 additions and 10 deletions
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34
Core/apu.c
View File

@ -323,11 +323,6 @@ void GB_apu_copy_buffer(GB_gameboy_t *gb, GB_sample_t *dest, size_t count)
void GB_apu_init(GB_gameboy_t *gb)
{
memset(&gb->apu, 0, sizeof(gb->apu));
// gb->apu.wave_channels[0].duty = gb->apu.wave_channels[1].duty = 4;
// gb->apu.lfsr = 0x7FFF;
for (int i = 0; i < 4; i++) {
gb->apu.left_enabled[i] = gb->apu.right_enabled[i] = true;
}
gb->apu.lf_div = 1;
gb->apu.noise_channel.sample_length = 1;
}
@ -374,7 +369,14 @@ uint8_t GB_apu_read(GB_gameboy_t *gb, uint8_t reg)
void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
{
if (!gb->apu.global_enable && reg != GB_IO_NR52) {
if (!gb->apu.global_enable && reg != GB_IO_NR52 && (gb->is_cgb ||
(
reg != GB_IO_NR11 &&
reg != GB_IO_NR21 &&
reg != GB_IO_NR31 &&
reg != GB_IO_NR41
)
)) {
return;
}
@ -397,7 +399,14 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
update_sample(gb, i, gb->apu.samples[i], 0);
}
break;
case GB_IO_NR52:
case GB_IO_NR52: {
uint8_t old_nrx1[] = {
gb->io_registers[GB_IO_NR11],
gb->io_registers[GB_IO_NR21],
gb->io_registers[GB_IO_NR31],
gb->io_registers[GB_IO_NR41]
};
if ((value & 0x80) && !gb->apu.global_enable) {
GB_apu_init(gb);
gb->apu.global_enable = true;
@ -408,9 +417,18 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
}
memset(&gb->apu, 0, sizeof(gb->apu));
memset(gb->io_registers + GB_IO_NR10, 0, GB_IO_WAV_START - GB_IO_NR10);
gb->apu.global_enable = false;
}
break;
if (!gb->is_cgb && (value & 0x80)) {
GB_apu_write(gb, GB_IO_NR11, old_nrx1[0] & 0x3F);
GB_apu_write(gb, GB_IO_NR21, old_nrx1[1] & 0x3F);
GB_apu_write(gb, GB_IO_NR31, old_nrx1[2]);
GB_apu_write(gb, GB_IO_NR41, old_nrx1[3]);
}
}
break;
/* Square channels */
case GB_IO_NR10:

2
Core/apu.h
View File

@ -33,8 +33,6 @@ typedef struct
uint8_t apu_cycles;
uint8_t samples[GB_N_CHANNELS];
bool left_enabled[GB_N_CHANNELS];
bool right_enabled[GB_N_CHANNELS];
bool is_active[GB_N_CHANNELS];
uint8_t div_divider; // The DIV register ticks the APU at 512Hz, but is then divided