FreeCalypso > hg > gsm-codec-lib
view libtwamr/g_pitch.c @ 480:332397bc80aa
doc/AMR-library-API: document public const data items
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sun, 19 May 2024 23:18:17 +0000 |
parents | bd4f660eb75a |
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 : g_pitch.c * Purpose : Compute the pitch (adaptive codebook) gain. * ******************************************************************************** */ /* ******************************************************************************** * MODULE INCLUDE FILE AND VERSION ID ******************************************************************************** */ #include "namespace.h" #include "g_pitch.h" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "tw_amr.h" #include "typedef.h" #include "basic_op.h" #include "oper_32b.h" #include "no_count.h" #include "cnst.h" /* ******************************************************************************** * PUBLIC PROGRAM CODE ******************************************************************************** */ /************************************************************************* * * FUNCTION: G_pitch * * PURPOSE: Compute the pitch (adaptive codebook) gain. * Result in Q14 (NOTE: 12.2 bit exact using Q12) * * DESCRIPTION: * The adaptive codebook gain is given by * * g = <x[], y[]> / <y[], y[]> * * where x[] is the target vector, y[] is the filtered adaptive * codevector, and <> denotes dot product. * The gain is limited to the range [0,1.2] (=0..19661 Q14) * *************************************************************************/ Word16 G_pitch ( /* o : Gain of pitch lag saturated to 1.2 */ enum Mode mode, /* i : AMR mode */ Word16 xn[], /* i : Pitch target. */ Word16 y1[], /* i : Filtered adaptive codebook. */ Word16 g_coeff[], /* i : Correlations need for gain quantization */ Word16 L_subfr /* i : Length of subframe. */ ) { Word16 i; Word16 xy, yy, exp_xy, exp_yy, gain; Word32 s; Word16 scaled_y1[L_SUBFR]; /* Usually dynamic allocation of (L_subfr) */ /* divide "y1[]" by 4 to avoid overflow */ for (i = 0; i < L_subfr; i++) { scaled_y1[i] = shr (y1[i], 2); move16 (); } /* Compute scalar product <y1[],y1[]> */ /* Q12 scaling / MR122 */ Overflow = 0; move16 (); s = 1L; move32 (); /* Avoid case of all zeros */ for (i = 0; i < L_subfr; i++) { s = L_mac (s, y1[i], y1[i]); } test (); if (Overflow == 0) /* Test for overflow */ { exp_yy = norm_l (s); yy = round (L_shl (s, exp_yy)); } else { s = 1L; move32 (); /* Avoid case of all zeros */ for (i = 0; i < L_subfr; i++) { s = L_mac (s, scaled_y1[i], scaled_y1[i]); } exp_yy = norm_l (s); yy = round (L_shl (s, exp_yy)); exp_yy = sub (exp_yy, 4); } /* Compute scalar product <xn[],y1[]> */ Overflow = 0; move16 (); s = 1L; move32 (); /* Avoid case of all zeros */ for (i = 0; i < L_subfr; i++) { s = L_mac(s, xn[i], y1[i]); } test (); if (Overflow == 0) { exp_xy = norm_l (s); xy = round (L_shl (s, exp_xy)); } else { s = 1L; move32 (); /* Avoid case of all zeros */ for (i = 0; i < L_subfr; i++) { s = L_mac (s, xn[i], scaled_y1[i]); } exp_xy = norm_l (s); xy = round (L_shl (s, exp_xy)); exp_xy = sub (exp_xy, 2); } g_coeff[0] = yy; move16 (); g_coeff[1] = sub (15, exp_yy); move16 (); g_coeff[2] = xy; move16 (); g_coeff[3] = sub (15, exp_xy); move16 (); /* If (xy < 4) gain = 0 */ i = sub (xy, 4); test (); if (i < 0) return ((Word16) 0); /* compute gain = xy/yy */ xy = shr (xy, 1); /* Be sure xy < yy */ gain = div_s (xy, yy); i = sub (exp_xy, exp_yy); /* Denormalization of division */ gain = shr (gain, i); /* if(gain >1.2) gain = 1.2 */ test (); if (sub (gain, 19661) > 0) { gain = 19661; move16 (); } test (); if (sub(mode, MR122) == 0) { /* clear 2 LSBits */ gain = gain & 0xfffC; logic16 (); } return (gain); }