fusee-sim 1.0.0

Deterministic simulation testing for Fusee: seeded scheduler, faulty disks and networks, and correctness checkers
Documentation 
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//! A small seeded generator (SplitMix64). Every random choice in a simulation
//! comes from one of these, so a seed reproduces a run exactly.

#[derive(Clone, Debug)]
pub struct Rng(u64);

impl Rng {
    pub fn new(seed: u64) -> Self {
        Self(seed ^ 0x9e37_79b9_7f4a_7c15)
    }

    pub fn next(&mut self) -> u64 {
        self.0 = self.0.wrapping_add(0x9e37_79b9_7f4a_7c15);
        let mut z = self.0;
        z = (z ^ (z >> 30)).wrapping_mul(0xbf58_476d_1ce4_e5b9);
        z = (z ^ (z >> 27)).wrapping_mul(0x94d0_49bb_1331_11eb);
        z ^ (z >> 31)
    }

    /// Uniform in `0..n` (`n > 0`).
    pub fn below(&mut self, n: u64) -> u64 {
        if n == 0 {
            return 0;
        }
        self.next() % n
    }

    pub fn chance(&mut self, per_mille: u32) -> bool {
        self.below(1000) < u64::from(per_mille)
    }

    pub fn shuffle<T>(&mut self, v: &mut [T]) {
        for i in (1..v.len()).rev() {
            let j = self.below(i as u64 + 1) as usize;
            v.swap(i, j);
        }
    }

    pub fn fork(&mut self) -> Self {
        Self::new(self.next())
    }
}