FreeCalypso > hg > gsm-codec-lib
view libgsmefr/syn_filt.c @ 282:9ee8ad3d4d30
frtest: rm gsmfr-hand-test and gsmfr-max-out utils
These hack programs were never properly documented and were written
only as part of a debug chase, in pursuit of a bug that ultimately
turned out to be in our then-hacky patch to osmo-bts-sysmo,
before beginning of proper patches in Osmocom. These hack programs
need to be dropped from the present sw package because they depend
on old libgsm, and we are eliminating that dependency.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Sun, 14 Apr 2024 05:44:47 +0000 |
parents | bb71c5414e71 |
children |
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/************************************************************************* * * FUNCTION: Syn_filt: * * PURPOSE: Perform synthesis filtering through 1/A(z). * *************************************************************************/ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "no_count.h" #include "sig_proc.h" /* m = LPC order == 10 */ #define m 10 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; }