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/* 16-bit signed integer dot product
* Portable C version
* Copyright 2004 Phil Karn
* May be used under the terms of the GNU Lesser General Public License (LGPL)
#include <stdlib.h>
#include "fec.h"
struct dotprod {
int len; /* Number of coefficients */
signed short *coeffs;
/* Create and return a descriptor for use with the dot product function */
void *initdp_port(signed short coeffs[],int len){
struct dotprod *dp;
int j;
if(len == 0)
return NULL;
dp = (struct dotprod *)calloc(1,sizeof(struct dotprod));
dp->len = len;
/* Just one copy of the coefficients for the C version */
dp->coeffs = (signed short *)calloc(len,sizeof(signed short));
dp->coeffs[j] = coeffs[j];
return (void *)dp;
/* Free a dot product descriptor created earlier */
void freedp_port(void *p){
struct dotprod *dp = (struct dotprod *)p;
if(dp->coeffs != NULL)
/* Compute a dot product given a descriptor and an input array
* The length is taken from the descriptor
long dotprod_port(void *p,signed short a[]){
struct dotprod *dp = (struct dotprod *)p;
long corr;
int i;
corr = 0;
corr += (long)a[i] * dp->coeffs[i];
return corr;