////////////////////////////////
//~ True randomness

#if PlatformIsWindows
#if 0
# define BCRYPT_RNG_ALG_HANDLE   ((void *)0x00000081)
u32 BCryptGenRandom(void *algorithm, u8 *buffer, u32 buffer_size, u32 flags);
#endif
void TrueRand(String buffer)
{
    BCryptGenRandom(BCRYPT_RNG_ALG_HANDLE, (u8 *)buffer.text, buffer.len, 0);
}
#else
# error TrueRand not implemented for this platform
#endif

////////////////////////////////
//~ Stateful randomness

u64 RandU64FromState(RandState *state)
{
    u64 seed = state->seed;
    if (seed == 0)
    {
        TrueRand(StringFromStruct(&seed));
        state->seed = seed;
    }
    return seed ^ RandU64FromSeed(++state->counter);
}

f64 RandF64FromState(RandState *state, f64 range_start, f64 range_end)
{
    return range_start + (range_end - range_start) * ((f64)(RandU64FromState(state) % RandMaxF64) / (f64)RandMaxF64);
}

////////////////////////////////
//~ Seeded randomness

/* Based on Jon Maiga's "mx3"
 * https://jonkagstrom.com/mx3/mx3_rev2.html
 */
u64 RandU64FromSeed(u64 seed)
{
    seed = (seed ^ (seed >> 32)) * 0xbea225f9eb34556d;
    seed = (seed ^ (seed >> 29)) * 0xbea225f9eb34556d;
    seed = (seed ^ (seed >> 32)) * 0xbea225f9eb34556d;
    seed = (seed ^ (seed >> 29));
    return seed;
}

u64 RandU64FromSeeds(u64 seed_a, u64 seed_b)
{
    return RandU64FromSeed((seed_a * 3) + seed_b);
}

f64 RandF64FromSeed(u64 seed, f64 range_start, f64 range_end)
{
    return range_start + (range_end - range_start) * ((f64)(RandU64FromSeed(seed) % RandMaxF64) / (f64)RandMaxF64);
}