1 /* 16-bit signed integer dot product 2 * Portable C version 3 * Copyright 2004 Phil Karn 4 * May be used under the terms of the GNU Lesser General Public License (LGPL) 5 */ 6 #include <stdlib.h> 7 #include "fec.h" 8 9 struct dotprod { 10 int len; /* Number of coefficients */ 11 12 signed short *coeffs; 13 }; 14 15 /* Create and return a descriptor for use with the dot product function */ 16 void *initdp_port(signed short coeffs[],int len){ 17 struct dotprod *dp; 18 int j; 19 20 if(len == 0) 21 return NULL; 22 23 dp = (struct dotprod *)calloc(1,sizeof(struct dotprod)); 24 dp->len = len; 25 26 /* Just one copy of the coefficients for the C version */ 27 dp->coeffs = (signed short *)calloc(len,sizeof(signed short)); 28 for(j=0;j<len;j++) 29 dp->coeffs[j] = coeffs[j]; 30 return (void *)dp; 31 } 32 33 34 /* Free a dot product descriptor created earlier */ 35 void freedp_port(void *p){ 36 struct dotprod *dp = (struct dotprod *)p; 37 38 if(dp->coeffs != NULL) 39 free(dp->coeffs); 40 free(dp); 41 } 42 43 /* Compute a dot product given a descriptor and an input array 44 * The length is taken from the descriptor 45 */ 46 long dotprod_port(void *p,signed short a[]){ 47 struct dotprod *dp = (struct dotprod *)p; 48 long corr; 49 int i; 50 51 corr = 0; 52 for(i=0;i<dp->len;i++){ 53 corr += (long)a[i] * dp->coeffs[i]; 54 } 55 return corr; 56 } 57 58 59
