Subversion Repositories bluespec_md6

/* testmemcpy.c

** Ronald L. Rivest

** 5/12/08

**

** Routine to test speed of memcpy vs just a loop, for

** various size blocks to move.

**

** The cutoff for 32-bit compilation onto my laptop gives

** a cutoff of about blocksize = 16; below that the loop

** is faster; above that memcpy is faster.

*/

#include <stdio.h>

#include <stdint.h>

#include <time.h>

typedef uint64_t md6_word;

md6_word A[8092];

md6_word B[8092];

int main()

{ int blocksize;

  time_t start_time, end_time;

  int i,j;

  int ntrials = 1000000000;

  printf("ntrials = %d\n",ntrials);

  for (blocksize = 1; blocksize<= 128; blocksize += blocksize)

    {

      printf("Blocksize = %d 64-bit words\n",blocksize);

      time(&start_time);

      for (i=0;i<ntrials;i++)

        memcpy(A,B,blocksize*sizeof(md6_word));

      time(&end_time);

      printf("  memcpy: %ld seconds.\n",(long)end_time-start_time);

      time(&start_time);

      for (i=0;i<ntrials;i++)

        for (j=0;j<blocksize;j++)

          A[j] = B[j];

      time(&end_time);

      printf("  loop: %ld seconds.\n",(long)end_time-start_time);

    }

}