gistfile1.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

unsigned int countOnes(unsigned int input) {
  // lab answer here
}

unsigned int countOnesSlow(unsigned int input) {
  int count = 0;
  while (input) {
    count += (input & 01);
    input >>= 1;
  }
  return count;
}

#define DATA_SIZE 100000000

int main() {
  srand(time(NULL));

  unsigned int* data;
  data = calloc(DATA_SIZE, sizeof(unsigned int));
  unsigned long i;
  for (i = 0; i < DATA_SIZE; ++i) {
    data[i] = rand();
  }

  clock_t start, end;

  start = clock();
  for (i = 0; i < DATA_SIZE; ++i) {
    countOnesSlow(data[i]);
  }
  end = clock();
  printf("countOnesSlow:\t%f sec\n", ((float)(end - start))/CLOCKS_PER_SEC);

  start = clock();
  for (i = 0; i < DATA_SIZE; ++i) {
    countOnes(data[i]);
  }
  end = clock();
  printf("countOnes:\t%f sec\n", ((float)(end - start))/CLOCKS_PER_SEC);

  for (i = 0; i < DATA_SIZE; ++i) {
    int a = countOnes(data[i]);
    int b = countOnesSlow(data[i]);
    if (a != b) {
      fprintf(stderr, "for %d: expected %d, got %d\n", data[i], a, b);
      return 1;
    }
  }

  return 0;
}