80 lines
2.3 KiB
C
80 lines
2.3 KiB
C
/*
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// Created by bruno on 16.2.2025.
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*/
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#include "audio.h"
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int pcm_buffer_empty(PcmVoice *pcm) {
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return pcm->head == pcm->tail;
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}
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int pcm_buffer_full(PcmVoice *pcm) {
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return ((pcm->tail + 1) % PCM_BUFFER_SIZE) == pcm->head;
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}
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void pcm_buffer_push(PcmVoice *pcm, uint16_t sample) {
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if (!pcm_buffer_full(pcm)) {
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pcm->buffer[pcm->tail] = sample;
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pcm->tail = (pcm->tail + 1) % PCM_BUFFER_SIZE;
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}
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}
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uint16_t pcm_buffer_pop(PcmVoice *pcm) {
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if (!pcm_buffer_empty(pcm)) {
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uint16_t sample = pcm->buffer[pcm->head];
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pcm->head = (pcm->head + 1) % PCM_BUFFER_SIZE;
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return sample;
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}
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return 0;
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}
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void audio_callback(void *userdata, Uint8 *stream, int len) {
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AudioData *audio = (AudioData *) userdata;
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int samples = len / sizeof(float);
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for (int i = 0; i < samples; i++) {
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float mix = 0.0f;
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int activeVoices = 0;
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for (int v = 0; v < NUM_SYNTH_VOICES; v++) {
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SynthVoice *voice = &audio->synthVoices[v];
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if (voice->volume == 0 || voice->frequency == 0) continue;
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float sample = 0.0f;
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float t = (float) voice->phase / 255.0f * 2.0f - 1.0f;
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switch (voice->waveform) {
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default:
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case WAVE_SINE:
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sample = sinf(voice->phase * 2.0f * M_PI / 256.0f);
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break;
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case WAVE_SQUARE:
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sample = (t >= 0.0f) ? 1.0f : -1.0f;
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break;
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case WAVE_SAWTOOTH:
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sample = t;
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break;
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case WAVE_TRIANGLE:
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sample = (t < 0) ? -t : t;
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break;
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case WAVE_NOISE:
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sample = ((float) rand() / RAND_MAX) * 2.0f - 1.0f;
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break;
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}
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voice->phase += (uint8_t) ((voice->frequency * 256) / SAMPLE_RATE);
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mix += sample * (voice->volume / 255.0f);
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activeVoices++;
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}
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PcmVoice *pcm = &audio->pcmVoice;
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if (pcm->volume > 0 && !pcm_buffer_empty(pcm)) {
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float pcmSample = pcm_buffer_pop(pcm) / 65535.0f;
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mix += pcmSample * (pcm->volume / 255.0f);
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activeVoices++;
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}
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((float *) stream)[i] = (activeVoices > 0) ? mix / activeVoices : 0.0f;
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}
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}
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