|
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 }
|
|
|
24 }
|
|
|
25
|
|
|
26 void audio_run(audio *context, uint32_t target)
|
|
|
27 {
|
|
|
28 while (context->cycles < target)
|
|
|
29 {
|
|
|
30 for (int i = 0; i < 4; i++)
|
|
|
31 {
|
|
|
32 if (context->timer_cur[i]) {
|
|
|
33 context->timer_cur[i]--;
|
|
|
34 if (!context->timer_cur[i]) {
|
|
|
35 context->value[i] = context->value[i] ? 0 : (context->volume[i] << 5);
|
|
|
36 }
|
|
|
37 } else {
|
|
|
38 context->timer_cur[i] = context->timer_load[i];
|
|
|
39 }
|
|
|
40 }
|
|
|
41 context->buffer_fraction += context->buffer_inc;
|
|
|
42 if (context->buffer_fraction >= BUFFER_INC_RES) {
|
|
|
43 context->buffer_fraction -= BUFFER_INC_RES;
|
|
|
44 context->writebuffer[context->buffer_pos++] =
|
|
|
45 context->value[0] + context->value[1] + context->value[2] + context->value[3];
|
|
|
46 if (context->buffer_pos == context->buffer_size) {
|
|
|
47 int16_t *tmp = context->playbuffer;
|
|
|
48 context->playbuffer = context->writebuffer;
|
|
|
49 context->writebuffer = tmp;
|
|
|
50 system_present_audio(context->playbuffer);
|
|
|
51 context->buffer_pos = 0;
|
|
|
52 }
|
|
|
53 }
|
|
|
54 context->cycles += context->clock_inc;
|
|
|
55 }
|
|
|
56 }
|
|
|
57
|
|
|
58 void audio_write_freq(audio *context, int channel, uint16_t value)
|
|
|
59 {
|
|
|
60 context->timer_cur[channel] = context->timer_load[channel] = value;
|
|
|
61 }
|
|
|
62
|
|
|
63 void audio_write_vol(audio *context, int pair, uint16_t value)
|
|
|
64 {
|
|
|
65 int channel = pair * 2;
|
|
|
66 context->value[channel] = context->volume[channel] = value >> 8;
|
|
|
67 channel++;
|
|
|
68 context->value[channel] = context->volume[channel] = value;
|
|
|
69 }
|
