46 lines
925 B
Rust
46 lines
925 B
Rust
/// A trait to represent RNG for u64 values.
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pub trait RandGen {
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fn gen(&mut self) -> u64;
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}
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// A simple XOR-shift RNG implementation, for code-generation.
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#[cfg(test)]
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pub struct SimpleRng(u64);
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#[cfg(test)]
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impl SimpleRng {
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pub fn new() -> Self {
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Self(4) // https://xkcd.com/221/
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}
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pub fn gen(&mut self) -> u64 {
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self.0 ^= self.0 >> 12;
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self.0 ^= self.0 << 25;
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self.0 ^= self.0 >> 27;
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self.0
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}
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}
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#[cfg(test)]
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impl RandGen for SimpleRng {
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fn gen(&mut self) -> u64 {
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self.gen()
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn rng() {
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let mut rng = SimpleRng::new();
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assert_eq!(rng.gen(), 134217733);
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assert_eq!(rng.gen(), 4504699139039237);
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assert_eq!(rng.gen(), 13512173405898766);
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assert_eq!(rng.gen(), 9225626310854853124);
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assert_eq!(rng.gen(), 29836777971867270);
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}
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}
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