From 1d94de5358a44e08d9c1a07ab76df0b85d029ab7 Mon Sep 17 00:00:00 2001 From: Nebuleon <2391500+Nebuleon@users.noreply.github.com> Date: Sun, 24 Sep 2023 22:26:02 -0400 Subject: [PATCH] Optimize the additive DAC code, fixing performance-related hangs (#21662) --- platforms/chibios/drivers/audio_dac_additive.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/platforms/chibios/drivers/audio_dac_additive.c b/platforms/chibios/drivers/audio_dac_additive.c index 22e4fa2608..7bb5cfffb5 100644 --- a/platforms/chibios/drivers/audio_dac_additive.c +++ b/platforms/chibios/drivers/audio_dac_additive.c @@ -121,24 +121,27 @@ __attribute__((weak)) uint16_t dac_value_generate(void) { /* doing additive wave synthesis over all currently playing tones = adding up * sine-wave-samples for each frequency, scaled by the number of active tones */ - uint16_t value = 0; - float frequency = 0.0f; + uint_fast16_t value = 0; + float frequency = 0.0f; - for (uint8_t i = 0; i < active_tones_snapshot_length; i++) { + for (size_t i = 0; i < active_tones_snapshot_length; i++) { /* Note: a user implementation does not have to rely on the active_tones_snapshot, but * could directly query the active frequencies through audio_get_processed_frequency */ frequency = active_tones_snapshot[i]; - dac_if[i] = dac_if[i] + ((frequency * AUDIO_DAC_BUFFER_SIZE) / AUDIO_DAC_SAMPLE_RATE) * 2 / 3; + float new_dac_if = dac_if[i]; + new_dac_if += frequency * ((float)AUDIO_DAC_BUFFER_SIZE / AUDIO_DAC_SAMPLE_RATE * 2.0f / 3.0f); /*Note: the 2/3 are necessary to get the correct frequencies on the * DAC output (as measured with an oscilloscope), since the gpt * timer runs with 3*AUDIO_DAC_SAMPLE_RATE; and the DAC callback * is called twice per conversion.*/ - dac_if[i] = fmodf(dac_if[i], AUDIO_DAC_BUFFER_SIZE); + while (new_dac_if >= AUDIO_DAC_BUFFER_SIZE) + new_dac_if -= AUDIO_DAC_BUFFER_SIZE; + dac_if[i] = new_dac_if; // Wavetable generation/lookup - uint16_t dac_i = (uint16_t)dac_if[i]; + size_t dac_i = (size_t)new_dac_if; #if defined(AUDIO_DAC_SAMPLE_WAVEFORM_SINE) value += dac_buffer_sine[dac_i] / active_tones_snapshot_length;