FreeCalypso > hg > gsm-codec-lib
view libgsmefr/g_pitch.c @ 65:cb080ec1817e
libgsmefr: dec_lag6.c compiles
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sat, 26 Nov 2022 02:50:06 +0000 |
parents | 49dd1ac8e75b |
children | d9229fdac1c7 |
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/************************************************************************* * * FUNCTION: G_pitch * * PURPOSE: Compute the pitch (adaptive codebook) gain. Result in 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] * *************************************************************************/ #include "typedef.h" #include "basic_op.h" #include "oper_32b.h" #include "count.h" #include "sig_proc.h" Word16 G_pitch ( /* (o) : Gain of pitch lag saturated to 1.2 */ Word16 xn[], /* (i) : Pitch target. */ Word16 y1[], /* (i) : Filtered adaptive codebook. */ Word16 L_subfr /* : Length of subframe. */ ) { Word16 i; Word16 xy, yy, exp_xy, exp_yy, gain; Word32 s; Word16 scaled_y1[80]; /* Usually dynamic allocation of (L_subfr) */ /* divide by 2 "y1[]" to avoid overflow */ for (i = 0; i < L_subfr; i++) { scaled_y1[i] = shr (y1[i], 2); move16 (); } /* Compute scalar product <y1[],y1[]> */ s = 0L; move32 (); /* Avoid case of all zeros */ for (i = 0; i < L_subfr; i++) { s = L_mac (s, y1[i], y1[i]); } test (); if (L_sub (s, MAX_32) != 0L) /* Test for overflow */ { s = L_add (s, 1L); /* Avoid case of all zeros */ 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++) { Carry = 0; move16 (); s = L_macNs (s, xn[i], y1[i]); test (); if (Overflow != 0) { break; } } 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); } /* 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 = add (exp_xy, 3 - 1); /* Denormalization of division */ i = sub (i, exp_yy); gain = shr (gain, i); /* if(gain >1.2) gain = 1.2 */ test (); if (sub (gain, 4915) > 0) { gain = 4915; move16 (); } return (gain); }