/*******************************************************************************                                                                             **       Copyright (C) 1992-1995 Tony Robinson                                 **                                                                             **       See the file LICENSE for conditions on distribution and usage         **                                                                             *******************************************************************************//* * $Id: poly.c,v 1.3 2002/01/27 15:37:21 jason Exp $ */#include <math.h>#include <stdio.h>#include <stdlib.h>#include "shorten.h"#ifdef HAVE_CONFIG_H#include "config.h"#endif#define ALPHA0 (3.0 / 2.0)#define ALPHA1 M_LN2int wav2poly(buf, nbuf, offset, version, psigbit, presbit) slong *buf; int nbuf;  slong offset; int version; float *psigbit, *presbit;{  slong sum0 = 0, sum1 = 0, sum2 = 0, sum3 = 0, sum;  slong last0 = buf[-1] - offset;  slong last1 = buf[-1] - buf[-2];  slong last2 = last1 - (buf[-2] - buf[-3]);  float alpha = (float) ((version == 0) ? ALPHA0 : ALPHA1);  int   i, fnd;  for(i = 0; i < nbuf; i++) {    slong diff0, diff1, diff2;    sum0 += labs(diff0 = buf[i] - offset);    sum1 += labs(diff1 = diff0 - last0);    sum2 += labs(diff2 = diff1 - last1);    sum3 += labs(        diff2 - last2);    last0 = diff0;    last1 = diff1;    last2 = diff2;  }  if(sum0 < MIN(MIN(sum1, sum2), sum3)) {    sum = sum0;    fnd = FN_DIFF0;  }  else if(sum1 < MIN(sum2, sum3)) {    sum = sum1;    fnd = FN_DIFF1;  }  else if(sum2 < sum3) {    sum = sum2;    fnd = FN_DIFF2;  }  else {    sum = sum3;    fnd = FN_DIFF3;  }  /* return the expected number of bits per original signal sample */  *psigbit = (float) ((sum0 > 0) ? log(alpha * sum0 / (double) nbuf) / M_LN2 : 0.0);  /* return the expected number of bits per residual signal sample */  *presbit = (float) ((sum  > 0) ? log(alpha * sum  / (double) nbuf) / M_LN2 : 0.0);  return(fnd);}