FreeCalypso > hg > gsm-codec-lib
view libgsmefr/pre_proc.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 | 3ea19a9aa2a1 |
children |
line wrap: on
line source
/************************************************************************* * * FUNCTION: Pre_Process() * * PURPOSE: Preprocessing of input speech. * * DESCRIPTION: * - 2nd order high pass filtering with cut off frequency at 80 Hz. * - Divide input by two. * *************************************************************************/ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "oper_32b.h" #include "no_count.h" #include "sig_proc.h" #include "cnst.h" #include "enc_state.h" /*------------------------------------------------------------------------* * * * Algorithm: * * * * y[i] = b[0]*x[i]/2 + b[1]*x[i-1]/2 + b[2]*x[i-2]/2 * * + a[1]*y[i-1] + a[2]*y[i-2]; * * * * * * Input is divided by two in the filtering process. * *------------------------------------------------------------------------*/ /* filter coefficients (fc = 80 Hz, coeff. b[] is divided by 2) */ static const Word16 b[3] = {1899, -3798, 1899}; static const Word16 a[3] = {4096, 7807, -3733}; /* Initialization of static values */ void Init_Pre_Process (struct EFR_encoder_state *st) { struct preproc_state *pps = &st->pre_proc; pps->y2_hi = 0; pps->y2_lo = 0; pps->y1_hi = 0; pps->y1_lo = 0; pps->x0 = 0; pps->x1 = 0; } void Pre_Process ( struct EFR_encoder_state *st, Word16 signal[], /* input/output signal */ Word16 lg) /* lenght of signal */ { struct preproc_state *pps = &st->pre_proc; Word16 i, x2; Word32 L_tmp; for (i = 0; i < lg; i++) { x2 = pps->x1; pps->x1 = pps->x0; pps->x0 = signal[i]; /* y[i] = b[0]*x[i]/2 + b[1]*x[i-1]/2 + b140[2]*x[i-2]/2 */ /* + a[1]*y[i-1] + a[2] * y[i-2]; */ L_tmp = Mpy_32_16 (pps->y1_hi, pps->y1_lo, a[1]); L_tmp = L_add (L_tmp, Mpy_32_16 (pps->y2_hi, pps->y2_lo, a[2])); L_tmp = L_mac (L_tmp, pps->x0, b[0]); L_tmp = L_mac (L_tmp, pps->x1, b[1]); L_tmp = L_mac (L_tmp, x2, b[2]); L_tmp = L_shl (L_tmp, 3); signal[i] = round (L_tmp); pps->y2_hi = pps->y1_hi; pps->y2_lo = pps->y1_lo; L_Extract (L_tmp, &pps->y1_hi, &pps->y1_lo); } return; }