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sound/gb.cpp: Fix cycle handling. [ValleyBell] (#9436)
* sound/gb.cpp: Fix cycle handling. [ValleyBell] * sound/gb.cpp: Prevent hypothetical shifting of negative numbers. Simplify update_noise_channel.
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wilbertpol
GitHub
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267b329f9f
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123839f027
@ -348,32 +348,18 @@ void gameboy_sound_device::update_square_channel(struct SOUND &snd, uint64_t cyc
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if (snd.on)
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{
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// compensate for leftover cycles
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if (snd.cycles_left > 0)
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{
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// Emit sample(s)
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if (cycles <= snd.cycles_left)
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{
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snd.cycles_left -= cycles;
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cycles = 0;
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}
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else
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{
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cycles -= snd.cycles_left;
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snd.cycles_left = 0;
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}
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}
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snd.cycles_left += cycles;
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if (snd.cycles_left <= 0)
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return;
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if (cycles & 3)
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{
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snd.cycles_left = 4 - (cycles & 3);
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}
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cycles >>= 2;
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cycles = snd.cycles_left >> 2;
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snd.cycles_left &= 3;
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uint16_t distance = 0x800 - snd.frequency_counter;
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if (cycles >= distance)
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{
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cycles -= distance;
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distance = 0x800 - snd.frequency;
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uint64_t counter = 1 + cycles / distance;
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uint64_t counter = 1 + cycles / distance;
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snd.duty_count = (snd.duty_count + counter) & 0x07;
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snd.signal = wave_duty_table[snd.duty][snd.duty_count];
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@ -393,60 +379,34 @@ void dmg_apu_device::update_wave_channel(struct SOUND &snd, uint64_t cycles)
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if (snd.on)
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{
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// compensate for leftover cycles
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if (snd.cycles_left > 0)
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snd.cycles_left += cycles;
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while (snd.cycles_left >= 2)
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{
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if (cycles <= snd.cycles_left)
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snd.cycles_left -= 2;
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// Calculate next state
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snd.frequency_counter = (snd.frequency_counter + 1) & 0x7FF;
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snd.sample_reading = false;
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if (snd.frequency_counter == 0x7ff)
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{
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// Emit samples
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snd.cycles_left -= cycles;
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cycles = 0;
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snd.offset = (snd.offset + 1) & 0x1F;
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}
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else
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if (snd.frequency_counter == 0)
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{
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// Emit samples
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cycles -= snd.cycles_left;
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snd.cycles_left = 0;
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}
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}
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while (cycles > 0)
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{
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// Emit current sample
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// cycles -= 2
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if (cycles < 2)
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{
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snd.cycles_left = 2 - cycles;
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cycles = 0;
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}
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else
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{
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cycles -= 2;
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// Calculate next state
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snd.frequency_counter = (snd.frequency_counter + 1) & 0x7FF;
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snd.sample_reading = false;
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if (snd.frequency_counter == 0x7ff)
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// Read next sample
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snd.sample_reading = true;
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snd.current_sample = m_snd_regs[AUD3W0 + (snd.offset/2)];
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if (!(snd.offset & 0x01))
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{
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snd.offset = (snd.offset + 1) & 0x1F;
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snd.current_sample >>= 4;
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}
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if (snd.frequency_counter == 0)
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{
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// Read next sample
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snd.sample_reading = true;
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snd.current_sample = m_snd_regs[AUD3W0 + (snd.offset/2)];
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if (!(snd.offset & 0x01))
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{
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snd.current_sample >>= 4;
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}
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snd.current_sample = (snd.current_sample & 0x0F) - 8;
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snd.current_sample = (snd.current_sample & 0x0F) - 8;
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snd.signal = snd.level ? snd.current_sample / (1 << (snd.level - 1)) : 0;
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snd.signal = snd.level ? snd.current_sample / (1 << (snd.level - 1)) : 0;
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// Reload frequency counter
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snd.frequency_counter = snd.frequency;
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}
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// Reload frequency counter
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snd.frequency_counter = snd.frequency;
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}
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}
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}
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@ -458,28 +418,12 @@ void cgb04_apu_device::update_wave_channel(struct SOUND &snd, uint64_t cycles)
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if (snd.on)
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{
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// compensate for left over cycles
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if (snd.cycles_left > 0)
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{
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if (cycles <= snd.cycles_left)
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{
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// Emit samples
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snd.cycles_left -= cycles;
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cycles = 0;
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}
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else
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{
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// Emit samples
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snd.cycles_left += cycles;
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if (snd.cycles_left <= 0)
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return;
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cycles -= snd.cycles_left;
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snd.cycles_left = 0;
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}
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}
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if (cycles & 1)
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{
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snd.cycles_left = 1;
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}
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cycles >>= 1;
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cycles = (snd.cycles_left >> 1);
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snd.cycles_left &= 1;
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uint16_t distance = 0x800 - snd.frequency_counter;
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if (cycles >= distance)
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{
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@ -512,35 +456,21 @@ void cgb04_apu_device::update_wave_channel(struct SOUND &snd, uint64_t cycles)
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void gameboy_sound_device::update_noise_channel(struct SOUND &snd, uint64_t cycles)
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{
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if (cycles >= snd.cycles_left)
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snd.cycles_left += cycles;
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uint64_t period = noise_period_cycles();
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while (snd.cycles_left >= period)
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{
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cycles -= snd.cycles_left;
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uint64_t period = noise_period_cycles();
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uint64_t counter = 1 + cycles / period, i = 0;
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uint16_t start = snd.noise_lfsr;
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while (i < counter) {
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/* Using a Polynomial Counter (aka Linear Feedback Shift Register)
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Mode 4 has a 15 bit counter so we need to shift the
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bits around accordingly */
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uint16_t feedback = ((snd.noise_lfsr >> 1) ^ snd.noise_lfsr) & 1;
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snd.noise_lfsr = (snd.noise_lfsr >> 1) | (feedback << 14);
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if (snd.noise_short)
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{
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snd.noise_lfsr = (snd.noise_lfsr & ~(1 << 6)) | (feedback << 6);
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}
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i += 1;
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if (snd.noise_lfsr == start)
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{
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counter %= i;
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i = 0;
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}
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snd.cycles_left -= period;
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// Using a Polynomial Counter (aka Linear Feedback Shift Register)
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// Mode 4 has a 15 bit counter so we need to shift the bits around accordingly.
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uint16_t feedback = ((snd.noise_lfsr >> 1) ^ snd.noise_lfsr) & 1;
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snd.noise_lfsr = (snd.noise_lfsr >> 1) | (feedback << 14);
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if (snd.noise_short)
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{
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snd.noise_lfsr = (snd.noise_lfsr & ~(1 << 6)) | (feedback << 6);
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}
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snd.signal = (snd.noise_lfsr & 1) ? -1 : 1;
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snd.cycles_left = period - cycles % period;
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}
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else
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{
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snd.cycles_left -= cycles;
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}
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}
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@ -996,12 +926,8 @@ void gameboy_sound_device::sound_w_internal( int offset, uint8_t data )
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m_snd_3.length_counting = true;
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m_snd_3.frequency = ((m_snd_3.reg[4] & 0x7) << 8) | m_snd_3.reg[3];
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m_snd_3.frequency_counter = m_snd_3.frequency;
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// There is a tiny bit of delay in starting up the wave channel(?)
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//
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// Results from older code where corruption of wave ram was triggered when sample_reading == true:
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// 4 breaks test 09 (read wram), fixes test 10 (write trigger), breaks test 12 (write wram)
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// 6 fixes test 09 (read wram), breaks test 10 (write trigger), fixes test 12 (write wram)
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m_snd_3.cycles_left = 0 + 6;
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// There is a tiny bit of delay in starting up the wave channel
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m_snd_3.cycles_left = -6;
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m_snd_3.sample_reading = false;
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if (!dac_enabled(m_snd_3))
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@ -88,7 +88,7 @@ protected:
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bool length_counting;
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bool length_enabled;
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/* Mode 1, 2, 3 */
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uint64_t cycles_left;
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int64_t cycles_left;
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int8_t duty;
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/* Mode 1, 2, 4 */
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bool envelope_enabled;
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