#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

struct rngstate{
	uint64_t state[16];
	int idx;
};

static struct rngstate global_rng_state;

void init_rng(){
	uint64_t seed_val = (uint64_t)SEED_VAL;
	size_t c_idx = 0;
	for ( ; c_idx < 16; c_idx++ ){
		seed_val = seed_val * 0x13371337;
		seed_val = seed_val ^ (seed_val >> 16);
		global_rng_state.state[c_idx] = seed_val;
	}
	return;
}

uint64_t get_rng_output(){
	int c_idx = global_rng_state.idx;
	const uint64_t next_state = global_rng_state.state[c_idx++];
	uint64_t use_state = global_rng_state.state[c_idx &= 15];
	use_state ^= use_state << 31;
	use_state ^= use_state >> 16;
	use_state ^= next_state ^ (next_state >> 31);
	global_rng_state.state[c_idx] = use_state;
	global_rng_state.idx = c_idx;
	return use_state * 0x1337;
}

unsigned int get_random_int( unsigned int min, unsigned int max ){
	if ( min >= max )
		return min;
	uint64_t nmax = 0xffffffffffffffff;
	uint64_t ncount = (max - min) + 1;
	uint64_t upper_limit = nmax - (nmax % ncount);
	uint64_t rand_int = get_rng_output();
	if ( rand_int > upper_limit ){
		while ( rand_int > upper_limit )
			rand_int = get_rng_output();
	}
	return (unsigned int)(rand_int % max) + min;
}