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comparison cdd_fader.c @ 2080:bafb757e1cd2

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Implement CD audio
author Michael Pavone <pavone@retrodev.com>
date Wed, 02 Feb 2022 01:10:07 -0800
parents
children cfd53c94fffb
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2079:5a2b759f6b2d 2080:bafb757e1cd2
1 #include "cdd_fader.h"
2 #include <stdio.h>
3
4 void cdd_fader_init(cdd_fader *fader)
5 {
6 fader->audio = render_audio_source(16934400, 384, 2);
7 fader->cur_attenuation = 0x4000;
8 fader->dst_attenuation = 0x4000;
9 fader->attenuation_step = 0;
10 }
11 void cdd_fader_attenuation_write(cdd_fader *fader, uint16_t attenuation)
12 {
13 fader->dst_attenuation = attenuation & 0xFFF0;
14 fader->flags = attenuation & 0xE;
15 if (fader->dst_attenuation > fader->cur_attenuation) {
16 fader->attenuation_step = (fader->dst_attenuation - fader->cur_attenuation) >> 4;
17 } else if (fader->dst_attenuation < fader->cur_attenuation) {
18 fader->attenuation_step = (fader->cur_attenuation - fader->dst_attenuation) >> 4;
19 } else {
20 fader->attenuation_step = 0;
21 }
22 }
23
24 void cdd_fader_data(cdd_fader *fader, uint8_t byte)
25 {
26 fader->bytes[fader->byte_counter++] = byte;
27 if (fader->byte_counter == sizeof(fader->bytes)) {
28 fader->byte_counter = 0;
29 int32_t left = (fader->bytes[1] << 8) | fader->bytes[0];
30 int32_t right = (fader->bytes[3] << 8) | fader->bytes[2];
31 if (left & 0x8000) {
32 left |= 0xFFFF0000;
33 }
34 if (right & 0x8000) {
35 right |= 0xFFFF0000;
36 }
37 if (!fader->cur_attenuation) {
38 left = right = 0;
39 } else if (fader->cur_attenuation >= 4) {
40 left *= fader->cur_attenuation & 0x7FF0;
41 right *= fader->cur_attenuation & 0x7FF0;
42 left >>= 14;
43 right >>= 14;
44 } else {
45 //TODO: FIXME
46 left = right = 0;
47 }
48 render_put_stereo_sample(fader->audio, left, right);
49 if (fader->attenuation_step) {
50 if (fader->dst_attenuation > fader->cur_attenuation) {
51 fader->cur_attenuation += fader->attenuation_step;
52 if (fader->cur_attenuation >= fader->dst_attenuation) {
53 fader->cur_attenuation = fader->dst_attenuation;
54 fader->attenuation_step = 0;
55 }
56 } else {
57 fader->cur_attenuation -= fader->attenuation_step;
58 if (fader->cur_attenuation <= fader->dst_attenuation) {
59 fader->cur_attenuation = fader->dst_attenuation;
60 fader->attenuation_step = 0;
61 }
62 }
63 }
64 }
65 }