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November 29, 2025 22:26
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murmur3 in rust
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| pub fn murmur3_x64_64(data: &[u8], seed: u64) -> u64 { | |
| let mut h1 = seed; | |
| let mut h2 = seed; | |
| const C1: u64 = 0x87c37b91114253d5; | |
| const C2: u64 = 0x4cf5ad432745937f; | |
| let mut i = 0; | |
| let len = data.len(); | |
| while i + 16 <= len { | |
| let k1 = u64::from_le_bytes(data[i..i + 8].try_into().unwrap()); | |
| let k2 = u64::from_le_bytes(data[i + 8..i + 16].try_into().unwrap()); | |
| i += 16; | |
| let mut k1 = k1.wrapping_mul(C1); | |
| k1 = k1.rotate_left(31); | |
| k1 = k1.wrapping_mul(C2); | |
| h1 ^= k1; | |
| h1 = h1.rotate_left(27).wrapping_add(h2); | |
| h1 = h1.wrapping_mul(5).wrapping_add(0x52dce729); | |
| let mut k2 = k2.wrapping_mul(C2); | |
| k2 = k2.rotate_left(33); | |
| k2 = k2.wrapping_mul(C1); | |
| h2 ^= k2; | |
| h2 = h2.rotate_left(31).wrapping_add(h1); | |
| h2 = h2.wrapping_mul(5).wrapping_add(0x38495ab5); | |
| } | |
| // Tail | |
| let mut k1 = 0u64; | |
| let mut k2 = 0u64; | |
| let rem = len & 15; | |
| if rem > 0 { | |
| for j in (0..rem).rev() { | |
| let byte = data[i + j] as u64; | |
| if j < 8 { | |
| k1 |= byte << (j * 8); | |
| } else { | |
| k2 |= byte << ((j - 8) * 8); | |
| } | |
| } | |
| if k1 != 0 { | |
| k1 = k1.wrapping_mul(C1); | |
| k1 = k1.rotate_left(31); | |
| k1 = k1.wrapping_mul(C2); | |
| h1 ^= k1; | |
| } | |
| if k2 != 0 { | |
| k2 = k2.wrapping_mul(C2); | |
| k2 = k2.rotate_left(33); | |
| k2 = k2.wrapping_mul(C1); | |
| h2 ^= k2; | |
| } | |
| } | |
| // Finalization | |
| h1 ^= len as u64; | |
| h2 ^= len as u64; | |
| h1 = h1.wrapping_add(h2); | |
| h2 = h2.wrapping_add(h1); | |
| h1 = fmix64(h1); | |
| h2 = fmix64(h2); | |
| h1 = h1.wrapping_add(h2); | |
| // Optionally: h2 = h2.wrapping_add(h1); // we don’t use h2 | |
| h1 | |
| } | |
| fn fmix64(mut k: u64) -> u64 { | |
| k ^= k >> 33; | |
| k = k.wrapping_mul(0xff51afd7ed558ccd); | |
| k ^= k >> 33; | |
| k = k.wrapping_mul(0xc4ceb9fe1a85ec53); | |
| k ^= k >> 33; | |
| k | |
| } |
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