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// *Really* minimal PCG32 code / (c) 2014 M.E. O'Neill / pcg-random.org
// Licensed under Apache License 2.0 (NO WARRANTY, etc. see website)

typedef struct { uint64_t state;  uint64_t inc; } pcg32_random_t;

uint32_t pcg32_random_r(pcg32_random_t* rng)
{
    uint64_t oldstate = rng->state;
    // Advance internal state
    rng->state = oldstate * 6364136223846793005ULL + (rng->inc|1);
    // Calculate output function (XSH RR), uses old state for max ILP
    uint32_t xorshifted = ((oldstate >> 18u) ^ oldstate) >> 27u;
    uint32_t rot = oldstate >> 59u;
    return (xorshifted >> rot) | (xorshifted << ((-rot) & 31));
}

static __uint128_t g_lehmer64_state;

/**
* D. H. Lehmer, Mathematical methods in large-scale computing units.
* Proceedings of a Second Symposium on Large Scale Digital Calculating
* Machinery;
* Annals of the Computation Laboratory, Harvard Univ. 26 (1951), pp. 141-146.
*
* P L'Ecuyer,  Tables of linear congruential generators of different sizes and
* good lattice structure. Mathematics of Computation of the American
* Mathematical
* Society 68.225 (1999): 249-260.
*/

static inline void lehmer64_seed(uint64_t seed) {
  g_lehmer64_state = (((__uint128_t)splitmix64_stateless(seed, 0)) << 64) +
                     splitmix64_stateless(seed, 1);
}

static inline uint64_t lehmer64() {
  g_lehmer64_state *= UINT64_C(0xda942042e4dd58b5);
  return g_lehmer64_state >> 64;
}

#endif