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use std::{
collections::hash_map::DefaultHasher,
hash::{Hash, Hasher},
};
/// The 32-bit variant of the Xorshift PRNG algorithm.
///
/// Didn't feel like pulling in the `rand` crate, so have this here beauty instead.
#[repr(transparent)]
#[derive(Copy, Clone, Debug)]
pub struct Xorshift32(pub u32);
impl Xorshift32 {
pub fn from_id(id: &str) -> Self {
let mut hasher = DefaultHasher::new();
id.hash(&mut hasher);
let hash64 = hasher.finish();
let hash32 = ((hash64 & 0xFFFF_FFFF_0000_0000) >> 32) ^ (hash64 & 0xFFFF_FFFF);
Self(hash32.try_into().unwrap())
}
pub fn next(&mut self) -> u32 {
self.0 ^= self.0 << 13;
self.0 ^= self.0 >> 17;
self.0 ^= self.0 << 5;
self.0
}
}
impl Iterator for Xorshift32 {
type Item = u32;
fn next(&mut self) -> Option<Self::Item> { Some(self.next()) }
}
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