#include <stdlib.h>
#include <stdint.h>
uint64_t sum (char *p, size_t nwords)
{
uint64_t res = 0;
size_t i;
for (i = 0; i < nwords; i += 8) {
uint64_t tmp;
memcpy(&tmp, &p[i], sizeof(tmp));
res += tmp;
}
return res;
}