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/* 16-bit signed integer dot product
* SSE2 version
* Copyright 2004 Phil Karn
* May be used under the terms of the GNU Lesser General Public License (LGPL)
#define _XOPEN_SOURCE 600
#include <stdlib.h>
#include <memory.h>
#include "fec.h"
struct dotprod {
int len; /* Number of coefficients */
/* On a SSE2 machine, these hold 8 copies of the coefficients,
* preshifted by 0,1,..7 words to meet all possible input data
* alignments (see Intel ap559 on MMX dot products).
signed short *coeffs[8];
long dotprod_sse2_assist(signed short *a,signed short *b,int cnt);
/* Create and return a descriptor for use with the dot product function */
void *initdp_sse2(signed short coeffs[],int len){
struct dotprod *dp;
int i,j,blksize;
if(len == 0)
return NULL;
dp = (struct dotprod *)calloc(1,sizeof(struct dotprod));
dp->len = len;
/* Make 8 copies of coefficients, one for each data alignment,
* each aligned to 16-byte boundary
blksize = (1+(len+i-1)/8) * 8*sizeof(signed short);
posix_memalign((void **)&dp->coeffs[i],16,blksize);
dp->coeffs[i][j+i] = coeffs[j];
return (void *)dp;
/* Free a dot product descriptor created earlier */
void freedp_sse2(void *p){
struct dotprod *dp = (struct dotprod *)p;
int i;
if(dp->coeffs[i] != NULL)
/* Compute a dot product given a descriptor and an input array
* The length is taken from the descriptor
long dotprod_sse2(void *p,signed short a[]){
struct dotprod *dp = (struct dotprod *)p;
int al;
signed short *ar;
ar = (signed short *)((int)a & ~15);
al = a - ar;
/* Call assembler routine to do the work, passing number of 8-word blocks */
return dotprod_sse2_assist(ar,dp->coeffs[al],(dp->len+al-1)/8+1);