mirror of
https://github.com/libretro/bsnes-libretro.git
synced 2024-11-24 09:29:51 +00:00
Added channel 1 and 2, fixed accuracy issues with channel 3
This commit is contained in:
Lior Halphon
parent
2936f7fa57
commit
d65c2247e5
203
Core/apu.c
203
Core/apu.c
@ -6,6 +6,13 @@
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#define likely(x) __builtin_expect((x), 1)
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#define unlikely(x) __builtin_expect((x), 0)
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static const uint8_t duties[] = {
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0, 0, 0, 0, 0, 0, 1, 0,
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0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 0, 0,
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};
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static void refresh_channel(GB_gameboy_t *gb, unsigned index, unsigned cycles_offset)
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{
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unsigned multiplier = gb->apu_output.cycles_since_render + cycles_offset - gb->apu_output.last_update[index];
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@ -65,23 +72,119 @@ static void render(GB_gameboy_t *gb)
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void GB_apu_div_event(GB_gameboy_t *gb)
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{
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if (gb->apu.is_active[GB_WAVE] && gb->apu.wave_channel.length_enabled) {
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if (gb->apu.wave_channel.pulse_length) {
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gb->apu.wave_channel.pulse_length--;
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if (!gb->apu.global_enable) return;
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for (unsigned i = GB_SQUARE_2 + 1; i--;) {
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if (gb->apu.square_channels[i].length_enabled) {
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if (gb->apu.square_channels[i].pulse_length) {
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if (!--gb->apu.square_channels[i].pulse_length) {
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gb->apu.is_active[i] = false;
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update_sample(gb, i, 0, 0);
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}
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}
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}
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else {
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gb->apu.is_active[GB_WAVE] = false;
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gb->apu.wave_channel.current_sample = 0;
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update_sample(gb, GB_WAVE, 0, 0);
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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.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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else if (!(nrx2 & 8) && gb->apu.square_channels[i].current_volume > 0) {
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gb->apu.square_channels[i].current_volume--;
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}
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gb->apu.square_channels[i].volume_countdown = (nrx2 & 7) * 8;
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uint8_t duty = gb->io_registers[i == GB_SQUARE_1? GB_IO_NR11 :GB_IO_NR21] >> 6;
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update_sample(gb, i,
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duties[gb->apu.square_channels[i].current_sample_index + duty * 8]?
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gb->apu.square_channels[i].current_volume : 0,
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0);
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}
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}
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}
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gb->apu.square_sweep_div++;
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if ((gb->apu.square_sweep_div & 3) == 3) {
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if (gb->apu.square_sweep_countdown) {
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if (!--gb->apu.square_sweep_countdown) {
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gb->apu.square_channels[GB_SQUARE_1].sample_length ^= 0x7FF;
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uint16_t delta = gb->apu.square_channels[GB_SQUARE_1].sample_length >> (gb->io_registers[GB_IO_NR10] & 7);
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if (gb->io_registers[GB_IO_NR10] & 8) {
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gb->apu.square_channels[GB_SQUARE_1].sample_length -= delta;
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}
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else {
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gb->apu.square_channels[GB_SQUARE_1].sample_length += delta;
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}
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if (gb->apu.square_channels[GB_SQUARE_1].sample_length > 0x7f0) {
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gb->apu.square_sweep_stop_countdown = 0x13 - gb->apu.square_carry;
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}
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gb->apu.square_channels[GB_SQUARE_1].sample_length ^= 0x7FF;
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gb->apu.square_channels[GB_SQUARE_1].sample_length &= 0x7FF;
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gb->apu.square_sweep_countdown = ((gb->io_registers[GB_IO_NR10] >> 4) & 7);
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}
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}
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}
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if (gb->apu.wave_channel.length_enabled) {
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if (gb->apu.wave_channel.pulse_length) {
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if (!--gb->apu.wave_channel.pulse_length) {
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gb->apu.is_active[GB_WAVE] = false;
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gb->apu.wave_channel.current_sample = 0;
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update_sample(gb, GB_WAVE, 0, 0);
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}
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}
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}
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}
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void GB_apu_run(GB_gameboy_t *gb, uint8_t cycles)
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void GB_apu_run(GB_gameboy_t *gb)
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{
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/* Convert 4MHZ to 2MHz. cycles is always even. */
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cycles >>= 1;
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/* Convert 4MHZ to 2MHz. apu_cycles is always even. */
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uint8_t cycles = gb->apu.apu_cycles >> 1;
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gb->apu.apu_cycles = 0;
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if (!cycles) return;
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/* To align the square signal to 1MHz */
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gb->apu.square_carry ^= cycles & 1;
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if (gb->apu.square_sweep_stop_countdown) {
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if (gb->apu.square_sweep_stop_countdown > cycles) {
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gb->apu.square_sweep_stop_countdown -= cycles;
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}
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else {
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gb->apu.square_sweep_stop_countdown = 0;
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gb->apu.is_active[GB_SQUARE_1] = false;
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update_sample(gb, GB_SQUARE_1, 0, 0);
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}
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}
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for (unsigned i = GB_SQUARE_2 + 1; i--;) {
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if (gb->apu.is_active[i]) {
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uint8_t cycles_left = cycles;
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while (unlikely(cycles_left > gb->apu.square_channels[i].sample_countdown)) {
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cycles_left -= gb->apu.square_channels[i].sample_countdown + 1;
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gb->apu.square_channels[i].sample_countdown = gb->apu.square_channels[i].sample_length * 2 + 1;
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gb->apu.square_channels[i].current_sample_index++;
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gb->apu.square_channels[i].current_sample_index &= 0x7;
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uint8_t duty = gb->io_registers[i == GB_SQUARE_1? GB_IO_NR11 :GB_IO_NR21] >> 6;
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update_sample(gb, i,
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duties[gb->apu.square_channels[i].current_sample_index + duty * 8]?
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gb->apu.square_channels[i].current_volume : 0,
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cycles - cycles_left);
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gb->apu.square_channels[i].sample_emitted = true;
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}
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if (cycles_left) {
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gb->apu.square_channels[i].sample_countdown -= cycles_left;
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}
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}
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}
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gb->apu.wave_channel.wave_form_just_read = false;
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if (gb->apu.is_active[GB_WAVE]) {
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@ -154,6 +257,7 @@ void GB_apu_init(GB_gameboy_t *gb)
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gb->apu.left_enabled[i] = gb->apu.right_enabled[i] = true;
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}
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gb->apu.wave_channel.sample_length = 0x7FF;
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gb->apu.square_carry = 1;
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}
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uint8_t GB_apu_read(GB_gameboy_t *gb, uint8_t reg)
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@ -210,8 +314,7 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
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}
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gb->io_registers[reg] = value;
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switch (reg) {
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/* Globals */
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case GB_IO_NR50:
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@ -237,6 +340,77 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
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}
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break;
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case GB_IO_NR10:
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gb->apu.square_sweep_countdown = ((value >> 4) & 7);
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break;
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case GB_IO_NR11:
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case GB_IO_NR21: {
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unsigned index = reg == GB_IO_NR21? GB_SQUARE_2: GB_SQUARE_1;
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gb->apu.square_channels[index].pulse_length = (0x40 - (value & 0x3f)) * 2 - 1;
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break;
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}
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case GB_IO_NR12:
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case GB_IO_NR22: {
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/* TODO: What happens when changing bits 0-2 after triggering? */
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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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TODO: verify how "instant" the change is using PCM12*/
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unsigned index = reg == GB_IO_NR22? GB_SQUARE_2: GB_SQUARE_1;
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update_sample(gb, index, 0, 0);
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gb->apu.is_active[index] = false;
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}
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break;
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}
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case GB_IO_NR13:
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case GB_IO_NR23: {
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unsigned index = reg == GB_IO_NR23? GB_SQUARE_2: GB_SQUARE_1;
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gb->apu.square_channels[index].sample_length &= ~0xFF;
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gb->apu.square_channels[index].sample_length |= (~value) & 0xFF;
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break;
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}
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/* Square channels */
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case GB_IO_NR14:
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case GB_IO_NR24: {
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unsigned index = reg == GB_IO_NR24? GB_SQUARE_2: GB_SQUARE_1;
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gb->apu.square_channels[index].length_enabled = value & 0x40;
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gb->apu.square_channels[index].sample_length &= 0xFF;
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gb->apu.square_channels[index].sample_length |= ((~value) & 7) << 8;
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if (value & 0x80) {
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gb->apu.square_channels[index].current_sample_index = 7;
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if (!gb->apu.is_active[index]) {
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gb->apu.square_channels[index].sample_countdown = gb->apu.square_channels[index].sample_length * 2 + 6 - gb->apu.square_carry;
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}
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else {
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/* Timing quirk: if already active, sound starts 2 (2MHz) ticks earlier.
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if both active AND already emitted a sample, sound starts the next 1MHz tick,
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and one sample is skipped */
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if (!gb->apu.square_channels[index].sample_emitted) {
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gb->apu.square_channels[index].sample_countdown = gb->apu.square_channels[index].sample_length * 2 + 4 - gb->apu.square_carry;
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}
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else {
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gb->apu.square_channels[index].sample_countdown = gb->apu.square_carry;
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gb->apu.square_channels[index].current_sample_index = 0;
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}
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}
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gb->apu.square_channels[index].current_volume = gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] >> 4;
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gb->apu.square_channels[index].volume_countdown = (gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] & 7) * 8;
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if ((gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] & 0xF8) != 0) {
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gb->apu.is_active[index] = true;
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}
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if (gb->apu.square_channels[index].pulse_length == 0) {
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gb->apu.square_channels[index].pulse_length = 0x7F;
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}
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/* Note that we don't change the sample just yet! This was verified on hardware. */
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}
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break;
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}
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/* Wave channel */
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case GB_IO_NR30:
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gb->apu.wave_channel.enable = value & 0x80;
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@ -247,6 +421,7 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
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}
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break;
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case GB_IO_NR31:
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gb->apu.wave_channel.pulse_length = (0x100 - value) * 2 - 1;
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break;
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case GB_IO_NR32:
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gb->apu.wave_channel.shift = (uint8_t[]){4, 0, 1, 2}[(value >> 5) & 3];
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@ -283,9 +458,11 @@ 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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gb->apu.is_active[GB_WAVE] = true;
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gb->apu.wave_channel.pulse_length = (~gb->io_registers[GB_IO_NR31]) * 2;
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gb->apu.wave_channel.sample_countdown = gb->apu.wave_channel.sample_length + 3;
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gb->apu.wave_channel.current_sample_index = 0;
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if (gb->apu.wave_channel.pulse_length == 0) {
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gb->apu.wave_channel.pulse_length = 0x1FF;
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}
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/* Note that we don't change the sample just yet! This was verified on hardware. */
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}
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break;
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25
Core/apu.h
25
Core/apu.h
@ -31,15 +31,36 @@ enum GB_CHANNELS {
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typedef struct
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{
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bool global_enable;
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uint8_t apu_cycles;
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uint8_t samples[GB_N_CHANNELS];
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bool left_enabled[GB_N_CHANNELS];
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bool right_enabled[GB_N_CHANNELS];
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bool is_active[GB_N_CHANNELS];
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uint8_t square_carry; // The square channels tick at 1MHz instead of 2,
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// so we need a carry to divide the signal
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uint8_t square_sweep_div; // The DIV-APU ticks are divided by 4 to handle tone sweeping
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uint8_t square_sweep_countdown; // In 128Hz
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uint8_t square_sweep_stop_countdown; // In 2 MHz
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struct {
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uint16_t pulse_length; // Reloaded from NRX1 (xorred), in DIV ticks
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uint8_t current_volume; // Reloaded from NRX2
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uint8_t volume_countdown; // Reloaded from NRX2
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uint8_t current_sample_index;
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bool sample_emitted;
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uint16_t sample_countdown; // in APU ticks
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uint16_t sample_length; // Reloaded from NRX3, NRX4, in APU ticks
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bool length_enabled; // NRX4
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} square_channels[2];
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struct {
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bool enable; // NR30
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uint8_t pulse_length; // Reloaded from NR31 (xorred), in DIV ticks
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uint16_t pulse_length; // Reloaded from NR31 (xorred), in DIV ticks
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uint8_t shift; // NR32
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uint16_t sample_length; // NR33, NR34, in APU ticks
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bool length_enabled; // NR34
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@ -82,7 +103,7 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value);
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uint8_t GB_apu_read(GB_gameboy_t *gb, uint8_t reg);
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void GB_apu_div_event(GB_gameboy_t *gb);
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void GB_apu_init(GB_gameboy_t *gb);
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void GB_apu_run(GB_gameboy_t *gb, uint8_t cycles);
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void GB_apu_run(GB_gameboy_t *gb);
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#endif
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#endif /* apu_h */
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@ -65,6 +65,7 @@ enum {
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GB_IO_NR12 = 0x12, // Channel 1 Volume Envelope (R/W)
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GB_IO_NR13 = 0x13, // Channel 1 Frequency lo (Write Only)
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GB_IO_NR14 = 0x14, // Channel 1 Frequency hi (R/W)
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/* NR20 does not exist */
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GB_IO_NR21 = 0x16, // Channel 2 Sound Length/Wave Pattern Duty (R/W)
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GB_IO_NR22 = 0x17, // Channel 2 Volume Envelope (R/W)
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GB_IO_NR23 = 0x18, // Channel 2 Frequency lo data (W)
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@ -74,9 +75,7 @@ enum {
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GB_IO_NR32 = 0x1c, // Channel 3 Select output level (R/W)
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GB_IO_NR33 = 0x1d, // Channel 3 Frequency's lower data (W)
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GB_IO_NR34 = 0x1e, // Channel 3 Frequency's higher data (R/W)
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/* Missing */
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/* NR40 does not exist */
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GB_IO_NR41 = 0x20, // Channel 4 Sound Length (R/W)
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GB_IO_NR42 = 0x21, // Channel 4 Volume Envelope (R/W)
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GB_IO_NR43 = 0x22, // Channel 4 Polynomial Counter (R/W)
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@ -97,7 +97,10 @@ void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
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advance_tima_state_machine(gb);
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for (int i = 0; i < cycles; i += 4) {
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/* This is a bit tricky. The DIV and APU are tightly coupled, but DIV is affected
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by the speed boost while the APU is not */
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GB_set_internal_div_counter(gb, gb->div_cycles + 4);
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gb->apu.apu_cycles += 4 >> gb->cgb_double_speed;
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}
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if (cycles > 4) {
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@ -127,9 +130,7 @@ void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
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gb->debugger_ticks += cycles;
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if (gb->cgb_double_speed) {
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cycles >>=1;
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}
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cycles >>= gb->cgb_double_speed;
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// Not affected by speed boost
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gb->hdma_cycles += cycles;
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@ -139,7 +140,7 @@ void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
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gb->cycles_since_last_sync += cycles;
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GB_dma_run(gb);
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GB_hdma_run(gb);
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GB_apu_run(gb, cycles);
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GB_apu_run(gb);
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GB_display_run(gb, cycles);
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GB_ir_run(gb);
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}
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@ -171,6 +172,7 @@ void GB_set_internal_div_counter(GB_gameboy_t *gb, uint32_t value)
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increase_tima(gb);
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}
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if (counter_overflow_check(gb->div_cycles, value, gb->cgb_double_speed? 0x4000 : 0x2000)) {
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GB_apu_run(gb);
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GB_apu_div_event(gb);
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}
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gb->div_cycles = value;
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