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// https://en.wikipedia.org/wiki/Linear_congruential_generator -> MMIX Donald Knuth
// modulo 2^64 = no need to do it explicitly
#include "types.h"
#define MULTIPLIER 6364136223846793005LL
#define INCREMENT 1442695040888963407LL
static uint64_t current;
void srand(uint64_t seed){
current = seed;
}
uint64_t randlong(void){
return (current = MULTIPLIER * current + INCREMENT);
}
#ifdef __UNIT_TEST_PRNG__
char bytewise_sum(uint64_t to_check){
char sum = 0;
int i;
for (i = 0 ; i < 8 ; i++)
sum += (to_check & (uint64_t)(0xFFULL << i*8)) >> i*8;
return sum;
}
int main(void){
srand(42);
int i;
for (i = 0 ; i < 1000 ; i++)
randlong();
uint64_t last = randlong();
return !((unsigned char)bytewise_sum(last) == 155);
}
#endif // __UNIT_TEST_PRNG__
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