FreeCalypso > hg > gsm-codec-lib
view libgsmefr/g_code.c @ 254:f931e704adc5
libtwamr: bits and parameter packing
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Fri, 05 Apr 2024 07:41:31 +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); }