Correct emulation of enabling and disabling the volume envelope. Correct emulation of a glitch where the volume envelope ticks when it usually wouldn’t.
This commit is contained in:
Lior Halphon
parent
3151821e6d
commit
ec0a879a93
76
Core/apu.c
76
Core/apu.c
@ -177,41 +177,34 @@ static void nrx2_glitch(uint8_t *volume, uint8_t value, uint8_t old_value)
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(*volume) &= 0xF;
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(*volume) &= 0xF;
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}
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}
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void GB_apu_div_event(GB_gameboy_t *gb)
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static void tick_square_envelope(GB_gameboy_t *gb, enum GB_CHANNELS index)
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{
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{
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if (!gb->apu.global_enable) return;
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uint8_t nrx2 = gb->io_registers[index == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
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if (gb->apu.skip_div_event) {
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gb->apu.skip_div_event = false;
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return;
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}
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gb->apu.div_divider++;
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if ((gb->apu.div_divider & 7) == 0) {
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if (gb->apu.square_channels[index].volume_countdown || (nrx2 & 7)) {
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for (unsigned i = GB_SQUARE_2 + 1; i--;) {
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if (!gb->apu.square_channels[index].volume_countdown || !--gb->apu.square_channels[index].volume_countdown) {
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uint8_t nrx2 = gb->io_registers[i == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
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if ((nrx2 & 8) && gb->apu.square_channels[index].current_volume < 0xF) {
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gb->apu.square_channels[index].current_volume++;
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if (gb->apu.square_channels[i].volume_countdown) {
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if (!--gb->apu.square_channels[i].volume_countdown) {
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if ((nrx2 & 8) && gb->apu.square_channels[i].current_volume < 0xF) {
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gb->apu.square_channels[i].current_volume++;
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}
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}
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else if (!(nrx2 & 8) && gb->apu.square_channels[i].current_volume > 0) {
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else if (!(nrx2 & 8) && gb->apu.square_channels[index].current_volume > 0) {
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gb->apu.square_channels[i].current_volume--;
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gb->apu.square_channels[index].current_volume--;
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}
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}
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gb->apu.square_channels[i].volume_countdown = nrx2 & 7;
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gb->apu.square_channels[index].volume_countdown = nrx2 & 7;
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if (gb->apu.is_active[i]) {
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if (gb->apu.is_active[index]) {
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update_square_sample(gb, i);
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update_square_sample(gb, index);
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}
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}
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}
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}
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}
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}
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}
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}
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static void tick_noise_envelope(GB_gameboy_t *gb)
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{
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uint8_t nr42 = gb->io_registers[GB_IO_NR42];
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uint8_t nr42 = gb->io_registers[GB_IO_NR42];
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if (gb->apu.noise_channel.volume_countdown) {
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if (gb->apu.noise_channel.volume_countdown || (nr42 & 7)) {
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if (!--gb->apu.noise_channel.volume_countdown) {
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if (!--gb->apu.noise_channel.volume_countdown) {
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if ((nr42 & 8) && gb->apu.noise_channel.current_volume < 0xF) {
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if ((nr42 & 8) && gb->apu.noise_channel.current_volume < 0xF) {
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gb->apu.noise_channel.current_volume++;
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gb->apu.noise_channel.current_volume++;
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@ -231,6 +224,36 @@ void GB_apu_div_event(GB_gameboy_t *gb)
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}
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}
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}
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}
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}
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}
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}
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void GB_apu_div_event(GB_gameboy_t *gb)
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{
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if (!gb->apu.global_enable) return;
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if (gb->apu.skip_div_event) {
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gb->apu.skip_div_event = false;
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return;
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}
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gb->apu.div_divider++;
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if ((gb->apu.div_divider & 1) == 0) {
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for (unsigned i = GB_SQUARE_2 + 1; i--;) {
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uint8_t nrx2 = gb->io_registers[i == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
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if (gb->apu.is_active[i] && gb->apu.square_channels[i].volume_countdown == 0 && (nrx2 & 7)) {
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tick_square_envelope(gb, i);
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}
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}
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if (gb->apu.is_active[GB_NOISE] && gb->apu.noise_channel.volume_countdown && (gb->io_registers[GB_IO_NR42] & 7)) {
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tick_noise_envelope(gb);
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}
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}
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if ((gb->apu.div_divider & 7) == 0) {
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for (unsigned i = GB_SQUARE_2 + 1; i--;) {
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tick_square_envelope(gb, i);
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}
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tick_noise_envelope(gb);
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}
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}
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if ((gb->apu.div_divider & 1) == 1) {
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if ((gb->apu.div_divider & 1) == 1) {
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@ -589,6 +612,10 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
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case GB_IO_NR12:
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case GB_IO_NR12:
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case GB_IO_NR22: {
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case GB_IO_NR22: {
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unsigned index = reg == GB_IO_NR22? GB_SQUARE_2: GB_SQUARE_1;
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unsigned index = reg == GB_IO_NR22? GB_SQUARE_2: GB_SQUARE_1;
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if (((value & 0x7) == 0) && ((gb->io_registers[reg] & 0x7) != 0)) {
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/* Envelope disabled */
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gb->apu.square_channels[index].volume_countdown = 0;
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}
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if ((value & 0xF8) == 0) {
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if ((value & 0xF8) == 0) {
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/* According to Blargg's test ROM this should disable the channel instantly
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/* According to Blargg's test ROM this should disable the channel instantly
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TODO: verify how "instant" the change is using PCM12 */
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TODO: verify how "instant" the change is using PCM12 */
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@ -785,7 +812,10 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
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}
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}
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case GB_IO_NR42: {
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case GB_IO_NR42: {
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if (((value & 0x7) == 0) && ((gb->io_registers[reg] & 0x7) != 0)) {
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/* Envelope disabled */
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gb->apu.noise_channel.volume_countdown = 0;
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}
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if ((value & 0xF8) == 0) {
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if ((value & 0xF8) == 0) {
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/* According to Blargg's test ROM this should disable the channel instantly
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/* According to Blargg's test ROM this should disable the channel instantly
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TODO: verify how "instant" the change is using PCM12 */
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TODO: verify how "instant" the change is using PCM12 */
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