/* * 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/add.c,v 1.2 1993/01/29 18:23:15 jutta Exp $ *//* *  See private.h for the more commonly used macro versions. */#include	<stdio.h>#include	<assert.h>#include	"private.h"#include	"gsm.h"#include	"proto.h"#define	saturate(x) 	\	((x) < MIN_WORD ? MIN_WORD : (x) > MAX_WORD ? MAX_WORD: (x))word gsm_add P2((a,b), word a, word b){	longword sum = (longword)a + (longword)b;	return saturate(sum);}word gsm_sub P2((a,b), word a, word b){	longword diff = (longword)a - (longword)b;	return saturate(diff);}word gsm_mult P2((a,b), word a, word b){	if (a == MIN_WORD && b == MIN_WORD) return MAX_WORD;	else return (word) (SASR( (longword)a * (longword)b, 15 ));}word gsm_mult_r P2((a,b), word a, word b){	if (b == MIN_WORD && a == MIN_WORD) return MAX_WORD;	else {		longword prod = (longword)a * (longword)b + 16384;		prod >>= 15;		return prod & 0xFFFF;	}}word gsm_abs P1((a), word a){	return a < 0 ? (a == MIN_WORD ? MAX_WORD : -a) : a;}longword gsm_L_mult P2((a,b),word a, word b){	assert( a != MIN_WORD || b != MIN_WORD );	return ((longword)a * (longword)b) << 1;}longword gsm_L_add P2((a,b), longword a, longword b){	if (a < 0) {		if (b >= 0) return a + b;		else {			ulongword A = (ulongword)-(a + 1) + (ulongword)-(b + 1);			return A >= (ulongword)MAX_LONGWORD ? MIN_LONGWORD :-(longword)A-2;		}	}	else if (b <= 0) return a + b;	else {		ulongword A = (ulongword)a + (ulongword)b;		return A > (ulongword)MAX_LONGWORD ? MAX_LONGWORD : A;	}}longword gsm_L_sub P2((a,b), longword a, longword b){	if (a >= 0) {		if (b >= 0) return a - b;		else {			/* a>=0, b<0 */			ulongword A = (ulongword)a + -(b + 1);			return A >= (ulongword)MAX_LONGWORD ? MAX_LONGWORD : (A + 1);		}	}	else if (b <= 0) return a - b;	else {		/* a<0, b>0 */  		ulongword A = (ulongword)-(a + 1) + b;		return A >= (ulongword)MAX_LONGWORD ? MIN_LONGWORD : -A - 1;	}}static unsigned char bitoff[ 256 ] = {	 8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,	 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,	 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,	 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,	 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,	 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};word gsm_norm P1((a), longword a )/* * the number of left shifts needed to normalize the 32 bit * variable L_var1 for positive values on the interval * * with minimum of * minimum of 1073741824  (01000000000000000000000000000000) and * maximum of 2147483647  (01111111111111111111111111111111) * * * and for negative values on the interval with * minimum of -2147483648 (-10000000000000000000000000000000) and * maximum of -1073741824 ( -1000000000000000000000000000000). * * in order to normalize the result, the following * operation must be done: L_norm_var1 = L_var1 << norm( L_var1 ); * * (That's 'ffs', only from the left, not the right..) */{	assert(a != 0);	if (a < 0) {		if (a <= (longword)-1073741824) return 0;		a = ~a;	}	return    a & 0xffff0000 		? ( a & 0xff000000		  ?  -1 + bitoff[ (unsigned char) (0xFF & (a >> 24)) ]		  :   7 + bitoff[ (unsigned char) (0xFF & (a >> 16)) ])		: ( a & 0xff00		  ?  15 + bitoff[ (unsigned char) (0xFF & (a >> 8)) ]		  :  23 + bitoff[ (unsigned char) (0xFF & a) ] );}longword gsm_L_asl P2((a,n), longword a, int n){	if (n >= 32) return 0;	if (n <= -32) return -(a < 0);	if (n < 0) return gsm_asr(a, -n);	return a << n;}word gsm_asl P2((a,n), word a, int n){	if (n >= 16) return 0;	if (n <= -16) return -(a < 0);	if (n < 0) return gsm_asr(a, -n);	return a << n;}longword gsm_L_asr P2((a,n), longword a, int n){	if (n >= 32) return -(a < 0);	if (n <= -32) return 0;	if (n < 0) return a << -n;#	ifdef	SASR		return a >> n;#	else		if (a >= 0) return a >> n;		else return -(longword)( -(ulongword)a >> n );#	endif}word gsm_asr P2((a,n), word a, int n){	if (n >= 16) return -(a < 0);	if (n <= -16) return 0;	if (n < 0) return a << -n;#	ifdef	SASR		return a >> n;#	else		if (a >= 0) return a >> n;		else return -(word)( -(uword)a >> n );#	endif}/*  *  (From p. 46, end of section 4.2.5) * *  NOTE: The following lines gives [sic] one correct implementation *  	  of the div(num, denum) arithmetic operation.  Compute div *        which is the integer division of num by denum: with denum *	  >= num > 0 */word gsm_div P2((num,denum), word num, word denum){	longword	L_num   = num;	longword	L_denum = denum;	word		div 	= 0;	int		k 	= 15;	/* The parameter num sometimes becomes zero.	 * Although this is explicitly guarded against in 4.2.5,	 * we assume that the result should then be zero as well.	 */	/* assert(num != 0); */	assert(num >= 0 && denum >= num);	if (num == 0)	    return 0;	while (k--) {		div   <<= 1;		L_num <<= 1;		if (L_num >= L_denum) {			L_num -= L_denum;			div++;		}	}	return div;}