/*************************************************************************	DIFMAG Version 49*************************************************************************  Compute Average Magnitude Difference Function** Inputs:*  SPEECH - Low pass filtered speech*  LPITA  - Length of speech buffer*  TAU    - Table of lags*  LTAU   - Number of lag values to compute*  MAXLAG - Maximum possible lag value* Outputs:*  AMDF   - Average Magnitude Difference for each lag in TAU*  MINPTR - Index of minimum AMDF value*  MAXPTR - Index of maximum AMDF value*/#include <math.h>#include "lpcdefs.h"difmag( speech, tau, ltau, maxlag, amdf, minptr, maxptr )int maxlag, *minptr, *maxptr, ltau;int tau[];float speech[], amdf[];{int i, j, n1, n2;float sum;*minptr = 1;*maxptr = 1;for(i=1;i<=ltau;i++)	{	n1 = (maxlag-tau[i]) *0.5 + 1;	n2 = n1 + MAXWIN - 1;	sum = 0.;	for(j=n1;j<=n2;j+=4)	{		sum += (float)fabs((double) (speech[j] - speech[j+tau[i]]) );	}	amdf[i] = sum;	if( amdf[i] < amdf[*minptr]) 		*minptr = i;	if( amdf[i] > amdf[*maxptr])		*maxptr = i;}}