Working PCG32 generator, updated from https://github.com/EricIO/pcg-rust

pcg32.rs

// Copyright 2015 Eric Skoglund
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at

//     http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Updates by Warren Henning, 2018

pub struct Pcg32Random {
    pub state: u64,
    pub inc: u64,
}

pub fn pcg32_random_r(rng: &mut Pcg32Random) -> u32 {
    let oldstate = rng.state;
    rng.state = oldstate.wrapping_mul(6364136223846793005u64).wrapping_add(rng.inc);
    let xorshifted = (((oldstate >> 18) ^ oldstate) >> 27) as u32;
    let rot = oldstate >> 59;
    let srot = -(rot as i64);
    return (xorshifted >> rot) | (xorshifted << (srot & 31));
}

pub fn pcg32_srandom_r(rng : &mut Pcg32Random, initstate : u64, initseq : u64) {
    rng.state = 0u64;
    rng.inc   = (initseq << 1u64) | 1u64;
    pcg32_random_r(rng);
    rng.state += initstate;
    pcg32_random_r(rng);
}

pub fn pcg32_boundedrand_r(rng: &mut Pcg32Random, bound : u32) -> u32 {
    let sbound = bound as i32;
    let threshold = (-sbound % sbound) as u32;
    loop {
        let r = pcg32_random_r(rng);
        if r >= threshold {
            return r % bound;
        }
    }
}