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73 lines
1.9 KiB
73 lines
1.9 KiB
/* 16-bit signed integer dot product
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* SSE2 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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#define _XOPEN_SOURCE 600
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#include <stdlib.h>
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#include <memory.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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/* On a SSE2 machine, these hold 8 copies of the coefficients,
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* preshifted by 0,1,..7 words to meet all possible input data
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* alignments (see Intel ap559 on MMX dot products).
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*/
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signed short *coeffs[8];
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};
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long dotprod_sse2_assist(signed short *a,signed short *b,int cnt);
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/* Create and return a descriptor for use with the dot product function */
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void *initdp_sse2(signed short coeffs[],int len){
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struct dotprod *dp;
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int i,j,blksize;
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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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/* Make 8 copies of coefficients, one for each data alignment,
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* each aligned to 16-byte boundary
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*/
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for(i=0;i<8;i++){
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blksize = (1+(len+i-1)/8) * 8*sizeof(signed short);
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posix_memalign((void **)&dp->coeffs[i],16,blksize);
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memset(dp->coeffs[i],0,blksize);
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for(j=0;j<len;j++)
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dp->coeffs[i][j+i] = coeffs[j];
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}
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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_sse2(void *p){
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struct dotprod *dp = (struct dotprod *)p;
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int i;
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for(i=0;i<8;i++)
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if(dp->coeffs[i] != NULL)
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free(dp->coeffs[i]);
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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_sse2(void *p,signed short a[]){
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struct dotprod *dp = (struct dotprod *)p;
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int al;
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signed short *ar;
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ar = (signed short *)((int)a & ~15);
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al = a - ar;
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/* Call assembler routine to do the work, passing number of 8-word blocks */
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return dotprod_sse2_assist(ar,dp->coeffs[al],(dp->len+al-1)/8+1);
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}
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