RTL271_1/evrcc/code/acelp_pf.c

/**********************************************************************
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To the extent to which the Source(s) may legally and freely do so, the 
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even though this Publication may contain the Contribution or a derivative 
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the Source's rights to license as herein provided.

When a Contribution is submitted by the Source(s) to assist the 
formulating groups of 3GPP2 or any of its Organizational Partners, it 
is proposed to the Committee as a basis for discussion and is not to 
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specifically reserve(s) the right to amend or modify the material 
contained in the Contribution. Nothing contained in the Contribution 
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With respect to the Software necessary for the practice of any or 
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*******************************************************************/
 
/*======================================================================*/
/*     Enhanced Variable Rate Codec - Bit-Exact C Specification         */
/*     Copyright (C) 1997-1998 Telecommunications Industry Association. */
/*     All rights reserved.                                             */
/*----------------------------------------------------------------------*/
/* Note:  Reproduction and use of this software for the design and      */
/*     development of North American Wideband CDMA Digital              */
/*     Cellular Telephony Standards is authorized by the TIA.           */
/*     The TIA does not authorize the use of this software for any      */
/*     other purpose.                                                   */
/*                                                                      */
/*     The availability of this software does not provide any license   */
/*     by implication, estoppel, or otherwise under any patent rights   */
/*     of TIA member companies or others covering any use of the        */
/*     contents herein.                                                 */
/*                                                                      */
/*     Any copies of this software or derivative works must include     */
/*     this and all other proprietary notices.                          */
/*======================================================================*/
#include "acelp_pf.h"
//#include "mathevrc.h"
#include "dsp_math.h"

#define NB_TRACK  5
#define STEP      5
#define L_SUBFR   55
#define L_SUBFR2  55

/*Note: Vector xn[], res2[], code[], y2[] and h1[] should be of lenght 55 !!! */

/*---------------------------------------------------------------------------*
 *  Function  ACELP_code()                                                   *
 *  ~~~~~~~~~~~~~~~~~~~~~~                                                   *
 *   Find Algebraic codebook.                                                *
 *--------------------------------------------------------------------------*/

void ACELP_Code(
					  Shortword xn[],	/* (i)     :Target signal for codebook.       */
					  Shortword res2[],		/* (i)     :Residual after pitch contribution */
					  Shortword h1[],	/* (i)     :Impulse response of filters.      */
					  Shortword T0,		/* (i)     :Pitch lag.                        */
					  Shortword pitch_gain,		/* (i)     :Pitch gain.                       */
					  Shortword l_subfr,	/* (i)     :Subframe lenght.                  */
					  Shortword code[],		/* (o)     :Innovative vector.                */
					  Shortword * gain_code,	/* (o)     :Innovative vector gain.           */
					  Shortword y2[],	/* (o)     :Filtered innovative vector.       */
					  Shortword * index,	/* (o)     :Index of codebook + signs         */
					  Shortword choice	/* (i)     :Choice of innovative codebook     */
			/*          0 -> 10 bits                      */
				/*          1 -> 35 bits                      */
)
{
	Shortword i, pit_sharp;
	Shortword dn[L_SUBFR2];

 /*-----------------------------------------------------------------*
  * - Find pitch sharpening.                                        *
  *-----------------------------------------------------------------*/
	/**===========================================================\
         Since the pitch gain is scaled by 1/2, therefore, the pitch_gain 
         should enlarge 2 to compensate the scale factor 
        ==============================================================*/

	pit_sharp = pitch_gain;
	/*  if(pit_sharp > 0.9) pit_sharp = 0.9;  */
	if (pit_sharp > 14746)
		pit_sharp = 14746;
	/*  if(pit_sharp < 0.2) pit_sharp = 0.2;  */
	if (pit_sharp < 3277)
		pit_sharp = 3277;
       pit_sharp = shl(pit_sharp,1);


 /*-----------------------------------------------------------------*
  * - Include fixed-gain pitch contribution into impulse resp. h1[] *
  *-----------------------------------------------------------------*/

	for (i = T0; i < l_subfr; i++)
	{							/* h[i] += pitch_sharp*h[i-T0] */
		h1[i] = add(h1[i], mult(h1[i - T0], pit_sharp));
	}

 /*-----------------------------------------------------------------*
  * Compute correlation between target "xn[]" and "h1[]".           *
  *-----------------------------------------------------------------*/

	/* Put xn[i] = res2[i] = 0; for i>l_subfr */

	for (i = l_subfr; i < L_SUBFR; i++)
		xn[i] = res2[i] = 0;

	/* Compute correlation between target x[] and H[] */

	cor_h_x(h1, xn, dn);

 /*-----------------------------------------------------------------*
  * - Innovative codebook search                                    *
  *-----------------------------------------------------------------*/

	if (choice == 0)
	{
		code_3i54_10bits(dn, l_subfr, h1, code, y2, index);
	}
	else
	{
		code_8i55_35bits(dn, res2, l_subfr, h1, code, y2, index);
	}

 /*-----------------------------------------------------------------*
  * Include fixed-gain pitch contribution into code[].              *
  *-----------------------------------------------------------------*/

	for (i = T0; i < l_subfr; i++)
	{							/* code[i] += pitch_sharp*code[i-T0] */
		code[i] = add(code[i], mult(code[i - T0], pit_sharp));
	}

 /*-----------------------------------------------------------------*
  * find gain of code.                                              *
  *-----------------------------------------------------------------*/

	*gain_code = G_code(xn, y2, l_subfr);

	return;
}

/*-------------------------------------------------------------------*
 * Function  cor_h_x()                                               *
 * ~~~~~~~~~~~~~~~~~~~                                               *
 * Compute correlation between target "x[]" and "h[]".               *
 *-------------------------------------------------------------------*
 *-------------------------------------------------------------------*/
void cor_h_x(
					   Shortword h[],	/* (i) Q12 : impulse response of weighted synthesis filter */
					   Shortword x[],	/* (i) Q0  : correlation between target and h[]            */
					   Shortword dn[]	/* (o) Q0  : correlation between target and h[]            */
)
{
	Shortword i, j, k;
	Longword s, y32[L_SUBFR], max, tot;

	/* first keep the result on 32 bits and find absolute maximum */

	tot = 5;

	for (k = 0; k < NB_TRACK; k++)
	{
		max = 0;
		for (i = k; i < L_SUBFR; i += STEP)
		{
			s = 0;
			for (j = i; j < L_SUBFR; j++)
				s = L_mac(s, x[j], h[j - i]);

			y32[i] = s;

			s = L_abs(s);

			if (L_sub(s, max) > (Longword) 0)
				max = s;
		}
		tot = L_add(tot, L_shr(max, 1));	/* tot += (2.0 x max) / 4.0 */
	}

	/* Find the number of right shifts to do on y32[] so that */
	/* 2.0 x sumation of all max of dn[] in each track not saturate. */

	j = sub(norm_l(tot), 2);	/* multiply tot by 4 */

	for (i = 0; i < L_SUBFR; i++)
	{
		dn[i] = round32(L_shl(y32[i], j));
	}
}

/*-------------------------------------------------------------------*
 * Function  G_code()                                                *
 * ~~~~~~~~~~~~~~~~~~                                                *
 * Compute gain of code.                                             *
 *-------------------------------------------------------------------*/

Shortword G_code(				
					Shortword xn2[],    /* out: Q0 Gain of innovation code. */
					Shortword y2[],		/* in:  Q10 Filtered inovation vector */
					Shortword l_subfr)	
{
	Shortword i;
	Shortword xy, yy, exp_xy, exp_yy, gain;
	Shortword scal_y2[L_SUBFR];
	Longword s;

/* Scale down Y[] by 2 to avoid overflow */

	for (i = 0; i < l_subfr; i++)
	{
		scal_y2[i] = shr(y2[i], 1);		/* Q10 --> Q9 */
	}

/* Compute scalar product <X[],Y[]> */

	s = 1;						/* 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  */

	if (xy <= 0)
		return ((Shortword) 0);

/* Compute scalar product <Y[],Y[]> */

	s = 0;
	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 = divide_s(xy, yy);

/* Denormalization of division */
	i = add(exp_xy, 5);
	i = sub(i, exp_yy);
        i=add(i,1); 

	gain = shr(gain, i);

	return (gain);
}