Mercurial > repos > simple16
annotate src/audio.c @ 43:6e7bfe83d2b0
Changed the design to vastly simplify the video hardware and support a 23-bit address space on the CPU
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Sat, 27 Aug 2016 22:38:31 -0700 |
| parents | 23bea9b9569f |
| children |
| rev | line source |
|---|---|
| 24 | 1 #include <stdint.h> |
| 2 #include <stdlib.h> | |
| 3 #include <string.h> | |
| 4 #include "audio.h" | |
| 5 #include "system.h" | |
| 6 | |
| 7 #define BUFFER_INC_RES 1000000000UL | |
| 8 | |
| 9 audio *alloc_audio(uint32_t master_clock, uint32_t clock_div, int sample_rate, int buffer_size) | |
| 10 { | |
| 11 size_t alloc_size = sizeof(audio) + buffer_size * sizeof(int16_t) * 2; | |
| 12 audio *context = malloc(alloc_size); | |
| 13 memset(context, 0, alloc_size); | |
| 14 context->writebuffer = context->buffer; | |
| 15 context->playbuffer = context->buffer + buffer_size; | |
| 16 | |
| 17 context->buffer_size = buffer_size; | |
| 18 context->clock_inc = clock_div; | |
| 19 context->buffer_inc = ((BUFFER_INC_RES * (uint64_t)sample_rate) / (uint64_t)master_clock) * clock_div; | |
| 20 for (int i = 0; i < NUM_CHANNELS; i++) | |
| 21 { | |
| 22 context->value[i] = context->volume[i] << 5; | |
| 23 } | |
|
41
23bea9b9569f
Fix silly bug in alloc_audio
Michael Pavone <pavone@retrodev.com>
parents:
24
diff
changeset
|
24 return context; |
| 24 | 25 } |
| 26 | |
| 27 void audio_run(audio *context, uint32_t target) | |
| 28 { | |
| 29 while (context->cycles < target) | |
| 30 { | |
| 31 for (int i = 0; i < 4; i++) | |
| 32 { | |
| 33 if (context->timer_cur[i]) { | |
| 34 context->timer_cur[i]--; | |
| 35 if (!context->timer_cur[i]) { | |
| 36 context->value[i] = context->value[i] ? 0 : (context->volume[i] << 5); | |
| 37 } | |
| 38 } else { | |
| 39 context->timer_cur[i] = context->timer_load[i]; | |
| 40 } | |
| 41 } | |
| 42 context->buffer_fraction += context->buffer_inc; | |
| 43 if (context->buffer_fraction >= BUFFER_INC_RES) { | |
| 44 context->buffer_fraction -= BUFFER_INC_RES; | |
| 45 context->writebuffer[context->buffer_pos++] = | |
| 46 context->value[0] + context->value[1] + context->value[2] + context->value[3]; | |
| 47 if (context->buffer_pos == context->buffer_size) { | |
| 48 int16_t *tmp = context->playbuffer; | |
| 49 context->playbuffer = context->writebuffer; | |
| 50 context->writebuffer = tmp; | |
| 51 system_present_audio(context->playbuffer); | |
| 52 context->buffer_pos = 0; | |
| 53 } | |
| 54 } | |
| 55 context->cycles += context->clock_inc; | |
| 56 } | |
| 57 } | |
| 58 | |
| 59 void audio_write_freq(audio *context, int channel, uint16_t value) | |
| 60 { | |
| 61 context->timer_cur[channel] = context->timer_load[channel] = value; | |
| 62 } | |
| 63 | |
| 64 void audio_write_vol(audio *context, int pair, uint16_t value) | |
| 65 { | |
| 66 int channel = pair * 2; | |
| 67 context->value[channel] = context->volume[channel] = value >> 8; | |
| 68 channel++; | |
| 69 context->value[channel] = context->volume[channel] = value; | |
| 70 } |