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comparison libgsmfrp/bad_frame.c @ 6:b2255a5d0519

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libgsmfrp: implement BFI handling
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 19 Nov 2022 21:18:53 +0000
parents
children 2361a7d8c1eb
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5:4812e00bc100 6:b2255a5d0519
1 /*
2 * In this module we implement our handling of BFI frame gaps.
3 */
4
5 #include <stdint.h>
6 #include <string.h>
7 #include "gsm_fr_preproc.h"
8 #include "internal.h"
9
10 static int reduce_xmaxc(gsm_byte *frame)
11 {
12 int mute_flag = 1;
13 unsigned sub, xmaxc;
14
15 for (sub = 0; sub < 4; sub++) {
16 xmaxc = ((frame[sub*7+6] & 0x1F) << 1) | (frame[sub*7+7] >> 7);
17 if (xmaxc > 4) {
18 xmaxc -= 4;
19 mute_flag = 0;
20 } else
21 xmaxc = 0;
22 frame[sub*7+6] &= 0xE0;
23 frame[sub*7+6] |= xmaxc >> 1;
24 frame[sub*7+7] &= 0x7F;
25 frame[sub*7+7] |= (xmaxc & 1) << 7;
26 }
27 return mute_flag;
28 }
29
30 void gsmfr_preproc_bfi(struct gsmfr_preproc_state *st, int taf, gsm_byte *frame)
31 {
32 int mute;
33
34 switch (st->rx_state) {
35 case NO_DATA:
36 memcpy(frame, &gsmfr_preproc_silence_frame, sizeof(gsm_frame));
37 return;
38 case SPEECH:
39 memcpy(frame, &st->speech_frame, sizeof(gsm_frame));
40 st->rx_state = SPEECH_MUTING;
41 return;
42 case SPEECH_MUTING:
43 mute = reduce_xmaxc(st->speech_frame);
44 memcpy(frame, &st->speech_frame, sizeof(gsm_frame));
45 if (mute)
46 st->rx_state = NO_DATA;
47 return;
48 case COMFORT_NOISE:
49 gsmfr_preproc_gen_cn(st, frame);
50 if (taf)
51 st->rx_state = LOST_SID;
52 return;
53 case LOST_SID:
54 gsmfr_preproc_gen_cn(st, frame);
55 if (taf)
56 st->rx_state = NO_DATA;
57 return;
58 }
59 }