FreeCalypso > hg > gsm-codec-lib
view libtwamr/syn_filt.c @ 495:aee13079db3c
libgsmhr1: implement SID reset
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Mon, 17 Jun 2024 23:25:19 +0000 |
parents | 2af94ba0c075 |
children |
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/* ******************************************************************************** * * GSM AMR-NB speech codec R98 Version 7.6.0 December 12, 2001 * R99 Version 3.3.0 * REL-4 Version 4.1.0 * ******************************************************************************** * * File : syn_filt.c * Purpose : Perform synthesis filtering through 1/A(z). * ******************************************************************************** */ /* ******************************************************************************** * MODULE INCLUDE FILE AND VERSION ID ******************************************************************************** */ #include "namespace.h" #include "syn_filt.h" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "typedef.h" #include "basic_op.h" #include "no_count.h" #include "cnst.h" /* ******************************************************************************** * LOCAL VARIABLES AND TABLES ******************************************************************************** */ /* *--------------------------------------* * Constants (defined in cnst.h * *--------------------------------------* * M : LPC order * *--------------------------------------* */ /* ******************************************************************************** * PUBLIC PROGRAM CODE ******************************************************************************** */ void Syn_filt ( Word16 a[], /* (i) : a[M+1] prediction coefficients (M=10) */ Word16 x[], /* (i) : input signal */ Word16 y[], /* (o) : output signal */ Word16 lg, /* (i) : size of filtering */ Word16 mem[], /* (i/o) : memory associated with this filtering. */ Word16 update /* (i) : 0=no update, 1=update of memory. */ ) { Word16 i, j; Word32 s; Word16 tmp[80]; /* This is usually done by memory allocation (lg+M) */ Word16 *yy; /* Copy mem[] to yy[] */ yy = tmp; move16 (); for (i = 0; i < M; i++) { *yy++ = mem[i]; move16 (); } /* Do the filtering. */ for (i = 0; i < lg; i++) { s = L_mult (x[i], a[0]); for (j = 1; j <= M; j++) { s = L_msu (s, a[j], yy[-j]); } s = L_shl (s, 3); *yy++ = round (s); move16 (); } for (i = 0; i < lg; i++) { y[i] = tmp[i + M]; move16 (); } /* Update of memory if update==1 */ test (); if (update != 0) { for (i = 0; i < M; i++) { mem[i] = y[lg - M + i]; move16 (); } } return; }