/*
  * memcpytest.c: Attempt to measure performance of memcpy.
  */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/time.h>
#include <string.h>
#include <unistd.h>


int
main(int argc, char **argv) {

     int             blocksz;                /* The block size to copy. */
     int             numblocks;              /* How many copies to do. */

     char            *buf;                   /* Input buffer. */
     typedef         struct  _BlockArray {
         char        *blockentry;
     } BlockArray;
     BlockArray      *blockarray;            /* Array of block entry 
ptrs. */
     int             i;
     struct          timeval starttp, endtp, elapsedtp;
     double          elapsed;


     if (argc != 3) {
         printf("usage %s blocksize num_blocks\n",
                 argv[0]);
         exit(1);
     } else {
         blocksz = atoi(argv[1]);
         numblocks = atoi(argv[2]);
     }

     /* Start timing setup. */
     gettimeofday(&starttp, NULL);


     /* Allocate source buffer and initialize to something trivial. */
     buf = (char *) malloc(blocksz);
     if (buf == NULL) {
         printf("out of memory initializing source buffer!\n");
         exit(2);
     }
     memset(buf, 1, blocksz);

     /* Allocate destination array of buffer pointers. */
     blockarray  = malloc(numblocks * sizeof(blockarray));
     if (blockarray == NULL) {
         printf("out of memory initializing destination array!\n");
         exit(2);
     }    /* Allocate a block entry for each element of blockarray. */
     for (i = 0; i < numblocks; i++) {
         blockarray[i].blockentry = malloc(blocksz);
         if (blockarray[i].blockentry == NULL) {
             printf("out of memory initializing destination array contents!\n");
             exit(2);
         }
     }

     gettimeofday(&endtp, NULL);
     timersub(&endtp, &starttp, &elapsedtp);
     elapsed = (double)elapsedtp.tv_sec + 
(double)elapsedtp.tv_usec/1000000.0;

     printf("%d malloc in %.4fs\n", numblocks, elapsed);


     /* Start timing copy now. */
     gettimeofday(&starttp, NULL);


     /* Perform the copy. */
     for (i = 0; i < numblocks; i++) {
         memcpy((void *)blockarray[i].blockentry, (void *)buf, blocksz);
     }

     gettimeofday(&endtp, NULL);
     timersub(&endtp, &starttp, &elapsedtp);
     elapsed = (double)elapsedtp.tv_sec + 
(double)elapsedtp.tv_usec/1000000.0;


     printf("%d memcpy of %d byte blocks in %.4fs\n",
             numblocks, blocksz, elapsed);

     free(buf);
     for (i = 0; i < numblocks; i++) {
         free(blockarray[i].blockentry);
     }
     free(blockarray);

     exit(0);

}