Mercurial > repos > simple16
view src/audio.c @ 49:5f30c4d18d79
Updated the HTML documentation a bit
author | Michael Pavone <pavone@retrodev.com> |
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date | Tue, 30 Aug 2016 22:04:29 -0700 |
parents | 23bea9b9569f |
children |
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#include <stdint.h> #include <stdlib.h> #include <string.h> #include "audio.h" #include "system.h" #define BUFFER_INC_RES 1000000000UL audio *alloc_audio(uint32_t master_clock, uint32_t clock_div, int sample_rate, int buffer_size) { size_t alloc_size = sizeof(audio) + buffer_size * sizeof(int16_t) * 2; audio *context = malloc(alloc_size); memset(context, 0, alloc_size); context->writebuffer = context->buffer; context->playbuffer = context->buffer + buffer_size; context->buffer_size = buffer_size; context->clock_inc = clock_div; context->buffer_inc = ((BUFFER_INC_RES * (uint64_t)sample_rate) / (uint64_t)master_clock) * clock_div; for (int i = 0; i < NUM_CHANNELS; i++) { context->value[i] = context->volume[i] << 5; } return context; } void audio_run(audio *context, uint32_t target) { while (context->cycles < target) { for (int i = 0; i < 4; i++) { if (context->timer_cur[i]) { context->timer_cur[i]--; if (!context->timer_cur[i]) { context->value[i] = context->value[i] ? 0 : (context->volume[i] << 5); } } else { context->timer_cur[i] = context->timer_load[i]; } } context->buffer_fraction += context->buffer_inc; if (context->buffer_fraction >= BUFFER_INC_RES) { context->buffer_fraction -= BUFFER_INC_RES; context->writebuffer[context->buffer_pos++] = context->value[0] + context->value[1] + context->value[2] + context->value[3]; if (context->buffer_pos == context->buffer_size) { int16_t *tmp = context->playbuffer; context->playbuffer = context->writebuffer; context->writebuffer = tmp; system_present_audio(context->playbuffer); context->buffer_pos = 0; } } context->cycles += context->clock_inc; } } void audio_write_freq(audio *context, int channel, uint16_t value) { context->timer_cur[channel] = context->timer_load[channel] = value; } void audio_write_vol(audio *context, int pair, uint16_t value) { int channel = pair * 2; context->value[channel] = context->volume[channel] = value >> 8; channel++; context->value[channel] = context->volume[channel] = value; }