FreeCalypso > hg > gsm-codec-lib

annotate libgsmfr2/full_dec.c @ 350:9b05bbc23b8a

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libgsmefr inline: make shift count guards 100% robust
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 23 Apr 2024 05:34:54 +0000
parents 4db5fc10fd1a
children f3246d109e2d
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4db5fc10fd1a libgsmfr2: implement full decoder
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1 /*
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2 * This module implements the "full decoder" functionality of libgsmfr2:
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3 * first the Rx DTX handler, then the regular GSM 06.10 decoder. This full
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4 * decoder also implements the optional homing feature, resetting both
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5 * components upon receiving DHF.
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6 */
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7
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8 #include <stdint.h>
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9 #include <stdlib.h>
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10 #include <string.h>
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11 #include "tw_gsmfr.h"
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12 #include "typedef.h"
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13 #include "ed_state.h"
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14 #include "pp_state.h"
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15
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16 struct gsmfr_fulldec_state {
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17 struct gsmfr_0610_state dec_0610;
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18 struct gsmfr_preproc_state rx_dtx;
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19 int is_homed;
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20 };
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21
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22 struct gsmfr_fulldec_state *gsmfr_fulldec_create(void)
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23 {
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24 struct gsmfr_fulldec_state *st;
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25
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26 st = malloc(sizeof(struct gsmfr_fulldec_state));
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27 if (st)
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28 gsmfr_fulldec_reset(st);
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29 return st;
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30 }
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31
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32 void gsmfr_fulldec_reset(struct gsmfr_fulldec_state *st)
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33 {
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34 gsmfr_0610_reset(&st->dec_0610);
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35 gsmfr_preproc_reset(&st->rx_dtx);
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36 st->is_homed = 1;
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37 }
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38
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39 static void emit_ehf_output(int16_t *pcm_out)
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40 {
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41 unsigned n;
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42
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43 for (n = 0; n < 160; n++)
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44 pcm_out[n] = 0x0008;
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45 }
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46
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47 void gsmfr_fulldec_good_frame(struct gsmfr_fulldec_state *st,
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48 const uint8_t *frame_in, int16_t *pcm_out)
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49 {
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50 uint8_t frame_mod[GSMFR_RTP_FRAME_LEN];
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51
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52 if (st->is_homed && !memcmp(frame_in, gsmfr_decoder_homing_frame, 12)) {
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53 emit_ehf_output(pcm_out);
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54 return;
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55 }
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56 memcpy(frame_mod, frame_in, GSMFR_RTP_FRAME_LEN);
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57 gsmfr_preproc_good_frame(&st->rx_dtx, frame_mod);
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58 gsmfr_0610_decode_frame(&st->dec_0610, frame_mod, pcm_out);
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59 if (!memcmp(frame_in, gsmfr_decoder_homing_frame, GSMFR_RTP_FRAME_LEN))
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60 gsmfr_fulldec_reset(st);
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61 else
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62 st->is_homed = 0;
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63 }
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64
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65 void gsmfr_fulldec_bfi(struct gsmfr_fulldec_state *st, int taf,
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66 int16_t *pcm_out)
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67 {
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68 uint8_t frame_mod[GSMFR_RTP_FRAME_LEN];
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69
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70 if (st->is_homed) {
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71 memset(pcm_out, 0, sizeof(int16_t) * 160);
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72 return;
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73 }
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74 gsmfr_preproc_bfi(&st->rx_dtx, taf, frame_mod);
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75 gsmfr_0610_decode_frame(&st->dec_0610, frame_mod, pcm_out);
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76 }