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Update 64-bit mixer to use better constants.

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This commit is contained in:
Nathan Vegdahl 2023-08-02 22:58:06 +02:00
parent 62138fd9a4
commit 12886bc5eb
1 changed files with 13 additions and 10 deletions
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23
src/lib.rs
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@ -25,23 +25,24 @@ pub fn mix32_inv(mut n: u32) -> u32 {
/// 64-bit bijective bit mixer. /// 64-bit bijective bit mixer.
/// ///
/// http://zimbry.blogspot.ch/2011/09/better-bit-mixing-improving-on.html /// http://zimbry.blogspot.ch/2011/09/better-bit-mixing-improving-on.html
/// (variant "Mix13")
pub fn mix64(mut n: u64) -> u64 { pub fn mix64(mut n: u64) -> u64 {
n ^= n >> 31; n ^= n >> 30;
n = n.wrapping_mul(0x7fb5d329728ea185); n = n.wrapping_mul(0xbf58476d1ce4e5b9);
n ^= n >> 27; n ^= n >> 27;
n = n.wrapping_mul(0x81dadef4bc2dd44d); n = n.wrapping_mul(0x94d049bb133111eb);
n ^= n >> 33; n ^= n >> 31;
n n
} }
/// Inverse of `mix64()`. /// Inverse of `mix64()`.
pub fn mix64_inv(mut n: u64) -> u64 { pub fn mix64_inv(mut n: u64) -> u64 {
n ^= n >> 33;
n = n.wrapping_mul(0x4d6dff26c61d8485);
n ^= (n >> 27) ^ (n >> 54);
n = n.wrapping_mul(0x4c5ff4596f4a2f4d);
n ^= (n >> 31) ^ (n >> 62); n ^= (n >> 31) ^ (n >> 62);
n = n.wrapping_mul(0x319642b2d24d8ec3);
n ^= (n >> 27) ^ (n >> 54);
n = n.wrapping_mul(0x96de1b173f119089);
n ^= (n >> 30) ^ (n >> 60);
n n
} }
@ -77,8 +78,10 @@ mod tests {
// #[test] // #[test]
// fn get_inverse() { // fn get_inverse() {
// // Panic, to print the result. // // Panic, to print the result.
// panic!("0x{:x}", compute_multiplicative_inverse_32(0x21f0aaad)); // panic!(
// panic!("0x{:x}", compute_multiplicative_inverse_32(0xd35a2d97)); // "0x{:x}",
// compute_multiplicative_inverse_64(0x94d049bb133111eb)
// );
// } // }
#[test] #[test]