/* cross.c *//*	Copyright (c) 1987, 1988, 1989 AT&T	*//*      Copyright (c) 1991-1994 Entropic Research Laboratory *//*	  All Rights Reserved	*//*	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T	*//*           and of Entgropic Research Laboratory               *//*	The copyright notice above does not evidence any	*//*	actual or intended publication of such source code.	*/#ifndef lint	static char *sccs_id = "@(#)cross.c	1.4 9/21/94		ATT, ESI ";#endif#include <stdio.h>#include <math.h>cross(data, size, start, nlags, engref, k1, maxloc, maxval, correl)     short *data, *correl;     int *maxloc;     double *engref, *k1, *maxval;     register int size, start, nlags;{  static float *ibuf=NULL, *obuf=NULL;  static int nin=0, nout=0;  register float *dp, *dq, *ds, sum;  register short *p;  register float engr, t, *dds, amax;  register double engc;  register int i, j, iloc;  int sizei, sizeo;    sizei = size + start + nlags + 1;  sizeo = nlags + 1;    if(nin < sizei) {    if(ibuf) ibuf = (float*)realloc(ibuf,sizeof(float)*sizei);    else  ibuf = (float*)malloc(sizeof(float)*sizei);    nin = sizei;    if(!ibuf) {      printf("Can't allocate buffer memory in cross()\n");      exit(-1);    }  }  if(nout < sizeo) {    if(obuf) obuf = (float*)realloc(obuf,sizeof(float)*sizeo);    else  obuf = (float*)malloc(sizeof(float)*sizeo);    nout = sizeo;    if(!obuf) {      printf("Can't allocate buffer memory in cross()\n");      exit(-1);    }  }  /* convert input data to floats */  for(i=0, sum = 0.0, p=data, dp=ibuf; i++ < sizei; ) {    *dp++ = t = *p++;    sum += t;  }  sum /= sizei;  for(i=0, dp=ibuf; i++ < sizei; ) {    *dp++ -= sum;  }    /* compute energy in reference window */  for(i=size, dp=ibuf, engr=0.0; i-- >0; ) {    sum = *dp++;    engr += sum * sum;  }  *engref = engr;  /* compute 1st lag for k1 computerion */  for(i=size-1, dq = ibuf, dp=ibuf+1, engc=0.0; i-- >0; )    engc += *dq++ * *dp++;  if(engr > 0.0) {    *k1 = engc/engr;    /* compute energy at first requested lag */      for(i=size, dp=ibuf+start, engc=0.0; i-- >0; ) {      sum = *dp++;      engc += sum * sum;    }    /* COMPUTE CORRELATIONS AT ALL REQUESTED LAGS */    for(i=0, dq=obuf, amax=0.0, iloc = -1; i < nlags; i++) {      for(j=size, sum=0.0, dp=ibuf, dds = ds = ibuf+i+start; j-- > 0; )	sum += *dp++ * *ds++;/*      *dq++ = t = (sum * 2.0/(engc + engr));*/      *dq++ = t = sum /sqrt(engc * engr);      engc -= *dds * *dds;      engc += *ds * *ds;      if(t > amax) {	amax = t;	iloc = i+start;      }    }    *maxloc = iloc;    *maxval = amax;    /* output normalized crosscorrelation as integers */    for(p=correl, i=sizeo, dp=obuf; i-- > 0; )      *p++ = .5 + (32767.0 * *dp++);  } else {    *k1 = 0.0;    *maxloc = 0;    *maxval = 0.0;    for(p=correl,i=sizeo; i-- > 0; )      *p++ = 0;  }}