FreeCalypso > hg > gsm-codec-lib
view libgsmefr/g_code.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 | 9dac98926a2d |
children |
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/************************************************************************* * * FUNCTION: G_code * * PURPOSE: Compute the innovative codebook gain. * * DESCRIPTION: * The innovative codebook gain is given by * * g = <x[], y[]> / <y[], y[]> * * where x[] is the target vector, y[] is the filtered innovative * codevector, and <> denotes dot product. * *************************************************************************/ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "no_count.h" #include "cnst.h" #include "codec.h" Word16 G_code ( /* out : Gain of innovation code */ Word16 xn2[], /* in : target vector */ Word16 y2[] /* in : filtered innovation vector */ ) { Word16 i; Word16 xy, yy, exp_xy, exp_yy, gain; Word16 scal_y2[L_SUBFR]; Word32 s; /* Scale down Y[] by 2 to avoid overflow */ for (i = 0; i < L_SUBFR; i++) { scal_y2[i] = shr (y2[i], 1); move16 (); } /* Compute scalar product <X[],Y[]> */ s = 1L; move32 (); /* Avoid case of all zeros */ for (i = 0; i < L_SUBFR; i++) { s = L_mac (s, xn2[i], scal_y2[i]); } exp_xy = norm_l (s); xy = extract_h (L_shl (s, exp_xy)); /* If (xy < 0) gain = 0 */ test (); if (xy <= 0) return ((Word16) 0); /* Compute scalar product <Y[],Y[]> */ s = 0L; move32 (); for (i = 0; i < L_SUBFR; i++) { s = L_mac (s, scal_y2[i], scal_y2[i]); } exp_yy = norm_l (s); yy = extract_h (L_shl (s, exp_yy)); /* compute gain = xy/yy */ xy = shr (xy, 1); /* Be sure xy < yy */ gain = div_s (xy, yy); /* Denormalization of division */ i = add (exp_xy, 5); /* 15-1+9-18 = 5 */ i = sub (i, exp_yy); gain = shr (gain, i); return (gain); }