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