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use tract_hir::internal::*;
#[derive(Copy, Clone)]
pub struct Philox4x32x10 {
key: u64,
counter: u128,
}
fn mul_hilo(a: u32, b: u32) -> (u32, u32) {
((((a as u64) * (b as u64)) >> 32) as u32, ((a as u64) * (b as u64)) as u32)
}
#[allow(non_upper_case_globals)]
impl Philox4x32x10 {
pub fn weird_tf_constructor(seed_lo: u64, seed_hi: u64) -> Philox4x32x10 {
let mut ph = Self::for_seed(seed_lo);
ph.skip_fast((seed_hi as u128) << 64);
ph
}
#[allow(unused)]
pub fn for_seeds(seed1: u32, seed2: u32) -> Philox4x32x10 {
Self::for_seed((seed2 as u64) << 32 | seed1 as u64)
}
pub fn for_seed(seed: u64) -> Philox4x32x10 {
Philox4x32x10 { key: seed, counter: 0 }
}
pub fn skip_fast(&mut self, n: u128) {
self.counter = self.counter.wrapping_add(n);
}
#[allow(unused)]
pub fn next_as_u32s(&mut self) -> [u32; 4] {
let v = self.next();
[v as u32, (v >> 32) as u32, (v >> 64) as u32, (v >> 96) as u32]
}
pub fn next(&mut self) -> u128 {
let mut key = self.key;
let mut counter = self.counter;
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
Self::raise_key(&mut key);
Self::compute_one(&mut counter, key);
self.counter = self.counter.wrapping_add(1);
counter
}
fn raise_key(key: &mut u64) {
const kPhiloxW32A: u32 = 0x9E3779B9;
const kPhiloxW32B: u32 = 0xBB67AE85;
let k0 = *key as u32;
let k1 = (*key >> 32) as u32;
let k0 = k0.wrapping_add(kPhiloxW32A) as u64;
let k1 = k1.wrapping_add(kPhiloxW32B) as u64;
*key = k1 << 32 | k0;
}
fn compute_one(counter: &mut u128, key: u64) {
const kPhiloxM4x32A: u32 = 0xD2511F53;
const kPhiloxM4x32B: u32 = 0xCD9E8D57;
let c0 = *counter as u32;
let c1 = (*counter >> 32) as u32;
let c2 = (*counter >> 64) as u32;
let c3 = (*counter >> 96) as u32;
let (hi0, lo0) = mul_hilo(kPhiloxM4x32A, c0);
let (hi1, lo1) = mul_hilo(kPhiloxM4x32B, c2);
let r0 = (hi1 ^ c1 ^ (key as u32)) as u128;
let r1 = lo1 as u128;
let r2 = (hi0 ^ c3 ^ ((key >> 32) as u32)) as u128;
let r3 = lo0 as u128;
*counter = r3 << 96 | r2 << 64 | r1 << 32 | r0
}
pub fn u32_iter(self) -> impl Iterator<Item = u32> {
self.flat_map(|big| {
tvec![big as u32, (big >> 32) as u32, (big >> 64) as u32, (big >> 96) as u32]
.into_iter()
})
}
}
impl Iterator for Philox4x32x10 {
type Item = u128;
fn next(&mut self) -> Option<u128> {
Some(Philox4x32x10::next(self))
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn seed() {
let mut ph = Philox4x32x10::for_seeds(1, 2);
assert_eq!(ph.next_as_u32s(), [0x598de3a, 0x98d2802e, 0x270f8f9e, 0xeab709d3]);
}
#[test]
fn zeros() {
let mut ph = Philox4x32x10::for_seeds(0, 0);
assert_eq!(ph.next_as_u32s(), [0x6627e8d5, 0xe169c58d, 0xbc57ac4c, 0x9b00dbd8]);
}
#[test]
fn ffff() {
let mut ph = Philox4x32x10::for_seeds(0xffffffff, 0xffffffff);
ph.skip_fast(0x_ffffffff_ffffffff_ffffffff_ffffffff);
assert_eq!(ph.next_as_u32s(), [0x408f276d, 0x41c83b0e, 0xa20bc7c6, 0x6d5451fd]);
}
#[test]
fn x243f6a88() {
let mut ph = Philox4x32x10::for_seeds(0xa4093822, 0x299f31d0);
ph.skip_fast(0x_03707344_13198a2e_85a308d3_243f6a88);
assert_eq!(ph.next_as_u32s(), [0xd16cfe09, 0x94fdcceb, 0x5001e420, 0x24126ea1]);
}
}