/* * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische * Universitaet Berlin.  See the accompanying file "COPYRIGHT" for * details.  THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE. *//* $Header: /home/kbs/jutta/src/gsm/gsm-1.0/src/RCS/lpc.c,v 1.1 1992/10/28 00:15:50 jutta Exp $ */#include <stdio.h>#include <assert.h>#include "private.h"#include "gsm.h"#include "proto.h"#undef	P/* *  4.2.4 .. 4.2.7 LPC ANALYSIS SECTION *//* 4.2.4 */static void Autocorrelation P2((s, L_ACF),	word     * s,		/* [0..159]	IN/OUT  */ 	longword * L_ACF)	/* [0..8]	OUT     *//* *  The goal is to compute the array L_ACF[k].  The signal s[i] must *  be scaled in order to avoid an overflow situation. */{	register int	k, i;	word		temp, smax, scalauto;	/*	longword	L_temp; */#ifdef	USE_FLOAT_MUL	float		float_s[160];	/*	longword	L_temp2; */#else	longword	L_temp2;#endif	/*  Dynamic scaling of the array  s[0..159]	 */	/*  Search for the maximum.	 */	smax = 0;	for (k = 0; k <= 159; k++) {		temp = GSM_ABS( s[k] );		if (temp > smax) smax = temp;	}	/*  Computation of the scaling factor.	 */	if (smax == 0) scalauto = 0;	else {		assert(smax > 0);		scalauto = 4 - gsm_norm( (longword)smax << 16 );/* sub(4,..) */	}	/*  Scaling of the array s[0...159]	 */	if (scalauto > 0) {# ifdef USE_FLOAT_MUL#   define SCALE(n)	\	case n: for (k = 0; k <= 159; k++) \			float_s[k] = (float)	\				(s[k] = GSM_MULT_R(s[k], 16384 >> (n-1)));\		break;# else #   define SCALE(n)	\	case n: for (k = 0; k <= 159; k++) \			s[k] = GSM_MULT_R( s[k], 16384 >> (n-1) );\		break;# endif /* USE_FLOAT_MUL */		switch (scalauto) {		SCALE(1)		SCALE(2)		SCALE(3)		SCALE(4)		}# undef	SCALE	}# ifdef	USE_FLOAT_MUL	else for (k = 0; k <= 159; k++) float_s[k] = (float) s[k];# endif	/*  Compute the L_ACF[..].	 */	{# ifdef	USE_FLOAT_MUL		register float * sp = float_s;		register float   sl = *sp;# else		word  * sp = s;		word    sl = *sp;# endif#	define STEP(k)	 L_ACF[k] += (longword)(sl * sp[ -(k) ]);#	define NEXTI	 sl = *++sp	for (k = 9; k--; L_ACF[k] = 0) ;	STEP (0);	NEXTI;	STEP(0); STEP(1);	NEXTI;	STEP(0); STEP(1); STEP(2);	NEXTI;	STEP(0); STEP(1); STEP(2); STEP(3);	NEXTI;	STEP(0); STEP(1); STEP(2); STEP(3); STEP(4);	NEXTI;	STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5);	NEXTI;	STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5); STEP(6);	NEXTI;	STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5); STEP(6); STEP(7);	for (i = 8; i <= 159; i++) {		NEXTI;		STEP(0);		STEP(1); STEP(2); STEP(3); STEP(4);		STEP(5); STEP(6); STEP(7); STEP(8);	}	for (k = 9; k--; L_ACF[k] <<= 1) ; 	}	/*   Rescaling of the array s[0..159]	 */	if (scalauto > 0) {		assert(scalauto <= 4); 		for (k = 160; k--; *s++ <<= scalauto) ;	}}#if defined(USE_FLOAT_MUL) && defined(FAST)static void Fast_Autocorrelation P2((s, L_ACF),	word * s,		/* [0..159]	IN/OUT  */ 	longword * L_ACF)	/* [0..8]	OUT     */{	register int	k, i;	float f_L_ACF[9];	float scale;	float          s_f[160];	register float *sf = s_f;	for (i = 0; i < 160; ++i) sf[i] = s[i];	for (k = 0; k <= 8; k++) {		register float L_temp2 = 0;		register float *sfl = sf - k;		for (i = k; i < 160; ++i) L_temp2 += sf[i] * sfl[i];		f_L_ACF[k] = L_temp2;	}	scale = MAX_LONGWORD / f_L_ACF[0];	for (k = 0; k <= 8; k++) {		L_ACF[k] = f_L_ACF[k] * scale;	}}#endif	/* defined (USE_FLOAT_MUL) && defined (FAST) *//* 4.2.5 */static void Reflection_coefficients P2( (L_ACF, r),	longword	* L_ACF,		/* 0...8	IN	*/	register word	* r			/* 0...7	OUT 	*/){	register int	i, m, n;	register word	temp;	register longword ltmp;	word		ACF[9];	/* 0..8 */	word		P[  9];	/* 0..8 */	word		K[  9]; /* 2..8 */	/*  Schur recursion with 16 bits arithmetic.	 */	if (L_ACF[0] == 0) {	/* everything is the same. */		for (i = 8; i--; *r++ = 0) ;		return;	}	assert( L_ACF[0] != 0 );	temp = gsm_norm( L_ACF[0] );	assert(temp >= 0 && temp < 32);	/* ? overflow ? */	for (i = 0; i <= 8; i++) ACF[i] = SASR( L_ACF[i] << temp, 16 );	/*   Initialize array P[..] and K[..] for the recursion.	 */	for (i = 1; i <= 7; i++) K[ i ] = ACF[ i ];	for (i = 0; i <= 8; i++) P[ i ] = ACF[ i ];	/*   Compute reflection coefficients	 */	for (n = 1; n <= 8; n++, r++) {		temp = P[1];		temp = GSM_ABS(temp);		if (P[0] < temp) {			for (i = n; i <= 8; i++) *r++ = 0;			return;		}		*r = gsm_div( temp, P[0] );		assert(*r >= 0);		if (P[1] > 0) *r = -*r;		/* r[n] = sub(0, r[n]) */		assert (*r != MIN_WORD);		if (n == 8) return; 		/*  Schur recursion		 */		temp = GSM_MULT_R( P[1], *r );		P[0] = GSM_ADD( P[0], temp );		for (m = 1; m <= 8 - n; m++) {			temp     = GSM_MULT_R( K[ m   ],    *r );			P[m]     = GSM_ADD(    P[ m+1 ],  temp );			temp     = GSM_MULT_R( P[ m+1 ],    *r );			K[m]     = GSM_ADD(    K[ m   ],  temp );		}	}}/* 4.2.6 */static void Transformation_to_Log_Area_Ratios P1((r),	register word	* r 			/* 0..7	   IN/OUT */)/* *  The following scaling for r[..] and LAR[..] has been used: * *  r[..]   = integer( real_r[..]*32768. ); -1 <= real_r < 1. *  LAR[..] = integer( real_LAR[..] * 16384 ); *  with -1.625 <= real_LAR <= 1.625 */{	register word	temp;	register int	i;	/* Computation of the LAR[0..7] from the r[0..7]	 */	for (i = 1; i <= 8; i++, r++) {		temp = *r;		temp = GSM_ABS(temp);		assert(temp >= 0);		if (temp < 22118) {			temp >>= 1;		} else if (temp < 31130) {			assert( temp >= 11059 );			temp -= 11059;		} else {			assert( temp >= 26112 );			temp -= 26112;			temp <<= 2;		}		*r = *r < 0 ? -temp : temp;		assert( *r != MIN_WORD );	}}/* 4.2.7 */static void Quantization_and_coding P1((LAR),	register word * LAR    	/* [0..7]	IN/OUT	*/){	register word	temp;	longword	ltmp;	/*	ulongword	utmp; reported as unused */	/*  This procedure needs four tables; the following equations	 *  give the optimum scaling for the constants:	 *  	 *  A[0..7] = integer( real_A[0..7] * 1024 )	 *  B[0..7] = integer( real_B[0..7] *  512 )	 *  MAC[0..7] = maximum of the LARc[0..7]	 *  MIC[0..7] = minimum of the LARc[0..7]	 */#	undef STEP#	define	STEP( A, B, MAC, MIC )		\		temp = GSM_MULT( A,   *LAR );	\		temp = GSM_ADD(  temp,   B );	\		temp = GSM_ADD(  temp, 256 );	\		temp = SASR(     temp,   9 );	\		*LAR  =  temp>MAC ? MAC - MIC : (temp<MIC ? 0 : temp - MIC); \		LAR++;	STEP(  20480,     0,  31, -32 );	STEP(  20480,     0,  31, -32 );	STEP(  20480,  2048,  15, -16 );	STEP(  20480, -2560,  15, -16 );	STEP(  13964,    94,   7,  -8 );	STEP(  15360, -1792,   7,  -8 );	STEP(   8534,  -341,   3,  -4 );	STEP(   9036, -1144,   3,  -4 );#	undef	STEP}void Gsm_LPC_Analysis P3((S, s,LARc),	struct gsm_state *S,	word 		 * s,		/* 0..159 signals	IN/OUT	*/        word 		 * LARc)	/* 0..7   LARc's	OUT	*/{	longword	L_ACF[9];#if defined(USE_FLOAT_MUL) && defined(FAST)	if (S->fast) Fast_Autocorrelation (s,	  L_ACF );	else#endif	Autocorrelation			  (s,	  L_ACF	);	Reflection_coefficients		  (L_ACF, LARc	);	Transformation_to_Log_Area_Ratios (LARc);	Quantization_and_coding		  (LARc);}