#include<iostream>
#include<assert.h>

inline int popcount_simple(uint64_t x) {
     int c = 0;
     for (uint64_t i = 0; i < 64; i++) {
	  if ((x & (1ull << i)) != 0) {
	       c++;
	  }
     }
     return c;
}

// Simple, very fast pseudo-random number generator
uint64_t RandLFSR(uint64_t &seed) {
     uint64_t bit;
     uint64_t temp = seed;
     bit = ((temp >> 0) ^ (temp >> 1) ^ (temp >> 3) ^ (temp >> 4)) & 0x1llu;
     seed = (temp >> 1) | (bit << 63);
     return seed;
}

int identity(uint64_t x) {
     return x;
}

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

     uint64_t key = 0xdeadbeef;

     if (argc != 2)
       {
	 printf("%s <algorithm>\n",argv[0]);
	 exit(-1);
       }

     int count = 100000000;
     int method = atoi(argv[1]);
     uint64_t sum = 0;
     
#define ALG(ALG_NUM, ALG_NAME) case ALG_NUM:				\
     for (int i=0; i < count; i++)					\
	  { sum += ALG_NAME (RandLFSR(key)); }				\
     printf("%d %s result: %llu\n",ALG_NUM, #ALG_NAME, sum);			\
     break
     
     switch(method) {
       ALG(0, identity);
       ALG(1, popcount_simple);
     }
     return sum;
}