/* testmemcpy.c
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/* testmemcpy.c
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** Ronald L. Rivest
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** Ronald L. Rivest
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** 5/12/08
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** 5/12/08
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**
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**
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** Routine to test speed of memcpy vs just a loop, for
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** Routine to test speed of memcpy vs just a loop, for
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** various size blocks to move.
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** various size blocks to move.
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**
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**
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** The cutoff for 32-bit compilation onto my laptop gives
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** The cutoff for 32-bit compilation onto my laptop gives
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** a cutoff of about blocksize = 16; below that the loop
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** a cutoff of about blocksize = 16; below that the loop
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** is faster; above that memcpy is faster.
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** is faster; above that memcpy is faster.
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*/
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*/
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#include <stdio.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <stdint.h>
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#include <time.h>
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#include <time.h>
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typedef uint64_t md6_word;
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typedef uint64_t md6_word;
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md6_word A[8092];
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md6_word A[8092];
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md6_word B[8092];
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md6_word B[8092];
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int main()
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int main()
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{ int blocksize;
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{ int blocksize;
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time_t start_time, end_time;
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time_t start_time, end_time;
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int i,j;
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int i,j;
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int ntrials = 1000000000;
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int ntrials = 1000000000;
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printf("ntrials = %d\n",ntrials);
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printf("ntrials = %d\n",ntrials);
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for (blocksize = 1; blocksize<= 128; blocksize += blocksize)
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for (blocksize = 1; blocksize<= 128; blocksize += blocksize)
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{
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{
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printf("Blocksize = %d 64-bit words\n",blocksize);
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printf("Blocksize = %d 64-bit words\n",blocksize);
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time(&start_time);
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time(&start_time);
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for (i=0;i<ntrials;i++)
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for (i=0;i<ntrials;i++)
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memcpy(A,B,blocksize*sizeof(md6_word));
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memcpy(A,B,blocksize*sizeof(md6_word));
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time(&end_time);
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time(&end_time);
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printf(" memcpy: %ld seconds.\n",(long)end_time-start_time);
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printf(" memcpy: %ld seconds.\n",(long)end_time-start_time);
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time(&start_time);
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time(&start_time);
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for (i=0;i<ntrials;i++)
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for (i=0;i<ntrials;i++)
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for (j=0;j<blocksize;j++)
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for (j=0;j<blocksize;j++)
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A[j] = B[j];
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A[j] = B[j];
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time(&end_time);
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time(&end_time);
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printf(" loop: %ld seconds.\n",(long)end_time-start_time);
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printf(" loop: %ld seconds.\n",(long)end_time-start_time);
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}
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}
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}
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}
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