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Removed for loop in APU

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This commit is contained in:
Lior Halphon 2016-09-13 17:06:35 +03:00
parent ff7b8a6854
commit eefc998e43
1 changed files with 47 additions and 48 deletions
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95
Core/apu.c
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@ -117,63 +117,62 @@ void GB_apu_get_samples_and_update_pcm_regs(GB_gameboy_t *gb, GB_sample_t *sampl
static void GB_apu_run_internal(GB_gameboy_t *gb) static void GB_apu_run_internal(GB_gameboy_t *gb)
{ {
for (;gb->apu.apu_cycles >= CPU_FREQUENCY/APU_FREQUENCY; gb->apu.apu_cycles -= CPU_FREQUENCY/APU_FREQUENCY) { uint32_t steps = gb->apu.apu_cycles / (CPU_FREQUENCY/APU_FREQUENCY);
gb->apu.apu_cycles %= (CPU_FREQUENCY/APU_FREQUENCY);
for (uint8_t i = 0; i < 4; i++) {
/* Phase */
gb->apu.wave_channels[i].phase += steps;
while (gb->apu.wave_channels[i].wave_length && gb->apu.wave_channels[i].phase >= gb->apu.wave_channels[i].wave_length) {
if (i == 3) {
gb->apu.lfsr = step_lfsr(gb->apu.lfsr, gb->apu.lfsr_7_bit);
}
gb->apu.wave_channels[i].phase -= gb->apu.wave_channels[i].wave_length;
}
/* Stop on Length */
if (gb->apu.wave_channels[i].stop_on_length) {
if (gb->apu.wave_channels[i].sound_length > 0) {
gb->apu.wave_channels[i].sound_length -= steps;
}
if (gb->apu.wave_channels[i].sound_length <= 0) {
gb->apu.wave_channels[i].amplitude = 0;
gb->apu.wave_channels[i].is_playing = false;
gb->apu.wave_channels[i].sound_length = i == 2? APU_FREQUENCY : APU_FREQUENCY / 4;
}
}
}
gb->apu.envelope_step_timer += steps;
while (gb->apu.envelope_step_timer >= APU_FREQUENCY / 64) {
gb->apu.envelope_step_timer -= APU_FREQUENCY / 64;
for (uint8_t i = 0; i < 4; i++) { for (uint8_t i = 0; i < 4; i++) {
/* Phase */ if (gb->apu.wave_channels[i].envelope_steps && !--gb->apu.wave_channels[i].cur_envelope_steps) {
gb->apu.wave_channels[i].phase++; gb->apu.wave_channels[i].amplitude = min(max(gb->apu.wave_channels[i].amplitude + gb->apu.wave_channels[i].envelope_direction * CH_STEP, 0), MAX_CH_AMP);
if (gb->apu.wave_channels[i].wave_length && gb->apu.wave_channels[i].phase >= gb->apu.wave_channels[i].wave_length) { gb->apu.wave_channels[i].cur_envelope_steps = gb->apu.wave_channels[i].envelope_steps;
if (i == 3) {
gb->apu.lfsr = step_lfsr(gb->apu.lfsr, gb->apu.lfsr_7_bit);
}
gb->apu.wave_channels[i].phase %= gb->apu.wave_channels[i].wave_length;
}
/* Stop on Length */
if (gb->apu.wave_channels[i].stop_on_length) {
if (gb->apu.wave_channels[i].sound_length > 0) {
gb->apu.wave_channels[i].sound_length -= 1;
}
if (gb->apu.wave_channels[i].sound_length <= 0) {
gb->apu.wave_channels[i].amplitude = 0;
gb->apu.wave_channels[i].is_playing = false;
gb->apu.wave_channels[i].sound_length = i == 2? APU_FREQUENCY : APU_FREQUENCY / 4;
}
} }
} }
}
gb->apu.envelope_step_timer += 1; gb->apu.sweep_step_timer += steps;
if (gb->apu.envelope_step_timer >= APU_FREQUENCY / 64) { while (gb->apu.sweep_step_timer >= APU_FREQUENCY / 128) {
gb->apu.envelope_step_timer -= APU_FREQUENCY / 64; gb->apu.sweep_step_timer -= APU_FREQUENCY / 128;
for (uint8_t i = 0; i < 4; i++) { if (gb->apu.wave_channels[0].sweep_steps && !--gb->apu.wave_channels[0].cur_sweep_steps) {
if (gb->apu.wave_channels[i].envelope_steps && !--gb->apu.wave_channels[i].cur_envelope_steps) {
gb->apu.wave_channels[i].amplitude = min(max(gb->apu.wave_channels[i].amplitude + gb->apu.wave_channels[i].envelope_direction * CH_STEP, 0), MAX_CH_AMP); // Convert back to GB format
gb->apu.wave_channels[i].cur_envelope_steps = gb->apu.wave_channels[i].envelope_steps; uint16_t temp = 2048 - gb->apu.wave_channels[0].wave_length / (APU_FREQUENCY / 131072);
}
// Apply sweep
temp = temp + gb->apu.wave_channels[0].sweep_direction *
(temp / (1 << gb->apu.wave_channels[0].sweep_shift));
if (temp > 2047) {
temp = 0;
} }
}
gb->apu.sweep_step_timer += 1; // Back to frequency
if (gb->apu.sweep_step_timer >= APU_FREQUENCY / 128) { gb->apu.wave_channels[0].wave_length = (2048 - temp) * (APU_FREQUENCY / 131072);
gb->apu.sweep_step_timer -= APU_FREQUENCY / 128;
if (gb->apu.wave_channels[0].sweep_steps && !--gb->apu.wave_channels[0].cur_sweep_steps) {
// Convert back to GB format
uint16_t temp = 2048 - gb->apu.wave_channels[0].wave_length / (APU_FREQUENCY / 131072);
// Apply sweep
temp = temp + gb->apu.wave_channels[0].sweep_direction *
(temp / (1 << gb->apu.wave_channels[0].sweep_shift));
if (temp > 2047) {
temp = 0;
}
// Back to frequency
gb->apu.wave_channels[0].wave_length = (2048 - temp) * (APU_FREQUENCY / 131072);
gb->apu.wave_channels[0].cur_sweep_steps = gb->apu.wave_channels[0].sweep_steps; gb->apu.wave_channels[0].cur_sweep_steps = gb->apu.wave_channels[0].sweep_steps;
}
} }
} }
} }