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annotate libgsmefr/weight_a.c @ 183:452c1d5a6268

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libgsmefr BFI w/o data: emit zero output after decoder reset In real-life usage, each EFR decoder session will most likely begin with lots of BFI frames before the first real frame arrives. However, because the spec-defined home state of the decoder is speech rather than CN, our regular logic for BFI w/o data would have to feed pseudorandom noise to the decoder (in the "fixed codebook excitation pulses" part), which is silly to do at the beginning of the decoder session right out of reset. Therefore, let's check reset_flag_old, and if we are still in the reset state, simply emit zero output.
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 03 Jan 2023 00:12:18 +0000
parents b651adfce60d
children
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1 /*************************************************************************
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2 *
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3 * FUNCTION: Weight_Ai
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4 *
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5 * PURPOSE: Spectral expansion of LP coefficients. (order==10)
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6 *
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7 * DESCRIPTION:
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8 * a_exp[i] = a[i] * fac[i-1] ,i=1,10
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9 *
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10 *************************************************************************/
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11
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12 #include "gsm_efr.h"
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13 #include "typedef.h"
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14 #include "namespace.h"
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15 #include "basic_op.h"
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16 #include "no_count.h"
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17 #include "sig_proc.h"
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19 /* m = LPC order == 10 */
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20 #define m 10
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22 void Weight_Ai (
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23 Word16 a[], /* (i) : a[m+1] LPC coefficients (m=10) */
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24 const Word16 fac[], /* (i) : Spectral expansion factors. */
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25 Word16 a_exp[] /* (o) : Spectral expanded LPC coefficients */
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26 )
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27 {
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28 Word16 i;
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30 a_exp[0] = a[0]; move16 ();
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31 for (i = 1; i <= m; i++)
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32 {
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33 a_exp[i] = round (L_mult (a[i], fac[i - 1])); move16 ();
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34 }
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36 return;
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37 }