/* Written in 2020 by Sebastiano Vigna (vigna@acm.org)

Forces a PCG generator to output the string "> John D. Cook <".

To the extent possible under law, the author has dedicated all copyright
and related and neighboring rights to this software to the public domain
worldwide. This software is distributed without any warranty.

See <http://creativecommons.org/publicdomain/zero/1.0/>. */


#include <stdio.h>
#include <stdint.h>

typedef __uint128_t uint128_t;

// -------
// PCG code Copyright by Melissa O'Neill

typedef __uint128_t pcg128_t;
#define PCG_128BIT_CONSTANT(high,low) ((((pcg128_t)high) << 64) + low)

struct pcg_state_128 {
	pcg128_t state;
};

#define PCG_DEFAULT_MULTIPLIER_128 \
        PCG_128BIT_CONSTANT(2549297995355413924ULL,4865540595714422341ULL)
#define PCG_DEFAULT_INCREMENT_128  \
        PCG_128BIT_CONSTANT(6364136223846793005ULL,1442695040888963407ULL)

static inline void pcg_oneseq_128_step_r(struct pcg_state_128* rng) {
	rng->state = rng->state * PCG_DEFAULT_MULTIPLIER_128 + PCG_DEFAULT_INCREMENT_128;
}

static inline uint64_t pcg_output_xsh_rs_128_64(pcg128_t state) {
	return (uint64_t)(((state >> 43u) ^ state) >> ((state >> 124u) + 45u));
}

static inline uint64_t pcg_oneseq_128_xsh_rs_64_random_r(struct pcg_state_128* rng) {
	pcg_oneseq_128_step_r(rng);
	return pcg_output_xsh_rs_128_64(rng->state);
}

int main(int argc, char* argv[]) {
	struct pcg_state_128 rng;
	rng.state = (__uint128_t)0x216c549ced70826b << 64 | 0x1b900f7fadcc7c16;
	for(;;) {
		uint64_t output = pcg_oneseq_128_xsh_rs_64_random_r(&rng);
		fwrite(&output, sizeof(output), 1, stdout);
	}
}