| //! This is a copy of `core::hash::sip` adapted to providing 128 bit hashes. |
| |
| use std::cmp; |
| use std::hash::Hasher; |
| use std::slice; |
| use std::ptr; |
| use std::mem; |
| |
| #[cfg(test)] |
| mod tests; |
| |
| #[derive(Debug, Clone)] |
| pub struct SipHasher128 { |
| k0: u64, |
| k1: u64, |
| length: usize, // how many bytes we've processed |
| state: State, // hash State |
| tail: u64, // unprocessed bytes le |
| ntail: usize, // how many bytes in tail are valid |
| } |
| |
| #[derive(Debug, Clone, Copy)] |
| #[repr(C)] |
| struct State { |
| // v0, v2 and v1, v3 show up in pairs in the algorithm, |
| // and simd implementations of SipHash will use vectors |
| // of v02 and v13. By placing them in this order in the struct, |
| // the compiler can pick up on just a few simd optimizations by itself. |
| v0: u64, |
| v2: u64, |
| v1: u64, |
| v3: u64, |
| } |
| |
| macro_rules! compress { |
| ($state:expr) => ({ |
| compress!($state.v0, $state.v1, $state.v2, $state.v3) |
| }); |
| ($v0:expr, $v1:expr, $v2:expr, $v3:expr) => |
| ({ |
| $v0 = $v0.wrapping_add($v1); $v1 = $v1.rotate_left(13); $v1 ^= $v0; |
| $v0 = $v0.rotate_left(32); |
| $v2 = $v2.wrapping_add($v3); $v3 = $v3.rotate_left(16); $v3 ^= $v2; |
| $v0 = $v0.wrapping_add($v3); $v3 = $v3.rotate_left(21); $v3 ^= $v0; |
| $v2 = $v2.wrapping_add($v1); $v1 = $v1.rotate_left(17); $v1 ^= $v2; |
| $v2 = $v2.rotate_left(32); |
| }); |
| } |
| |
| /// Loads an integer of the desired type from a byte stream, in LE order. Uses |
| /// `copy_nonoverlapping` to let the compiler generate the most efficient way |
| /// to load it from a possibly unaligned address. |
| /// |
| /// Unsafe because: unchecked indexing at i..i+size_of(int_ty) |
| macro_rules! load_int_le { |
| ($buf:expr, $i:expr, $int_ty:ident) => |
| ({ |
| debug_assert!($i + mem::size_of::<$int_ty>() <= $buf.len()); |
| let mut data = 0 as $int_ty; |
| ptr::copy_nonoverlapping($buf.get_unchecked($i), |
| &mut data as *mut _ as *mut u8, |
| mem::size_of::<$int_ty>()); |
| data.to_le() |
| }); |
| } |
| |
| /// Loads an u64 using up to 7 bytes of a byte slice. |
| /// |
| /// Unsafe because: unchecked indexing at start..start+len |
| #[inline] |
| unsafe fn u8to64_le(buf: &[u8], start: usize, len: usize) -> u64 { |
| debug_assert!(len < 8); |
| let mut i = 0; // current byte index (from LSB) in the output u64 |
| let mut out = 0; |
| if i + 3 < len { |
| out = u64::from(load_int_le!(buf, start + i, u32)); |
| i += 4; |
| } |
| if i + 1 < len { |
| out |= u64::from(load_int_le!(buf, start + i, u16)) << (i * 8); |
| i += 2 |
| } |
| if i < len { |
| out |= u64::from(*buf.get_unchecked(start + i)) << (i * 8); |
| i += 1; |
| } |
| debug_assert_eq!(i, len); |
| out |
| } |
| |
| |
| impl SipHasher128 { |
| #[inline] |
| pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher128 { |
| let mut state = SipHasher128 { |
| k0: key0, |
| k1: key1, |
| length: 0, |
| state: State { |
| v0: 0, |
| v1: 0, |
| v2: 0, |
| v3: 0, |
| }, |
| tail: 0, |
| ntail: 0, |
| }; |
| state.reset(); |
| state |
| } |
| |
| #[inline] |
| fn reset(&mut self) { |
| self.length = 0; |
| self.state.v0 = self.k0 ^ 0x736f6d6570736575; |
| self.state.v1 = self.k1 ^ 0x646f72616e646f6d; |
| self.state.v2 = self.k0 ^ 0x6c7967656e657261; |
| self.state.v3 = self.k1 ^ 0x7465646279746573; |
| self.ntail = 0; |
| |
| // This is only done in the 128 bit version: |
| self.state.v1 ^= 0xee; |
| } |
| |
| // Specialized write function that is only valid for buffers with len <= 8. |
| // It's used to force inlining of write_u8 and write_usize, those would normally be inlined |
| // except for composite types (that includes slices and str hashing because of delimiter). |
| // Without this extra push the compiler is very reluctant to inline delimiter writes, |
| // degrading performance substantially for the most common use cases. |
| #[inline] |
| fn short_write(&mut self, msg: &[u8]) { |
| debug_assert!(msg.len() <= 8); |
| let length = msg.len(); |
| self.length += length; |
| |
| let needed = 8 - self.ntail; |
| let fill = cmp::min(length, needed); |
| if fill == 8 { |
| self.tail = unsafe { load_int_le!(msg, 0, u64) }; |
| } else { |
| self.tail |= unsafe { u8to64_le(msg, 0, fill) } << (8 * self.ntail); |
| if length < needed { |
| self.ntail += length; |
| return; |
| } |
| } |
| self.state.v3 ^= self.tail; |
| Sip24Rounds::c_rounds(&mut self.state); |
| self.state.v0 ^= self.tail; |
| |
| // Buffered tail is now flushed, process new input. |
| self.ntail = length - needed; |
| self.tail = unsafe { u8to64_le(msg, needed, self.ntail) }; |
| } |
| |
| #[inline(always)] |
| fn short_write_gen<T>(&mut self, x: T) { |
| let bytes = unsafe { |
| slice::from_raw_parts(&x as *const T as *const u8, mem::size_of::<T>()) |
| }; |
| self.short_write(bytes); |
| } |
| |
| #[inline] |
| pub fn finish128(mut self) -> (u64, u64) { |
| let b: u64 = ((self.length as u64 & 0xff) << 56) | self.tail; |
| |
| self.state.v3 ^= b; |
| Sip24Rounds::c_rounds(&mut self.state); |
| self.state.v0 ^= b; |
| |
| self.state.v2 ^= 0xee; |
| Sip24Rounds::d_rounds(&mut self.state); |
| let _0 = self.state.v0 ^ self.state.v1 ^ self.state.v2 ^ self.state.v3; |
| |
| self.state.v1 ^= 0xdd; |
| Sip24Rounds::d_rounds(&mut self.state); |
| let _1 = self.state.v0 ^ self.state.v1 ^ self.state.v2 ^ self.state.v3; |
| (_0, _1) |
| } |
| } |
| |
| impl Hasher for SipHasher128 { |
| #[inline] |
| fn write_u8(&mut self, i: u8) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_u16(&mut self, i: u16) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_u32(&mut self, i: u32) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_u64(&mut self, i: u64) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_usize(&mut self, i: usize) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_i8(&mut self, i: i8) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_i16(&mut self, i: i16) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_i32(&mut self, i: i32) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_i64(&mut self, i: i64) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write_isize(&mut self, i: isize) { |
| self.short_write_gen(i); |
| } |
| |
| #[inline] |
| fn write(&mut self, msg: &[u8]) { |
| let length = msg.len(); |
| self.length += length; |
| |
| let mut needed = 0; |
| |
| if self.ntail != 0 { |
| needed = 8 - self.ntail; |
| self.tail |= unsafe { u8to64_le(msg, 0, cmp::min(length, needed)) } << (8 * self.ntail); |
| if length < needed { |
| self.ntail += length; |
| return |
| } else { |
| self.state.v3 ^= self.tail; |
| Sip24Rounds::c_rounds(&mut self.state); |
| self.state.v0 ^= self.tail; |
| self.ntail = 0; |
| } |
| } |
| |
| // Buffered tail is now flushed, process new input. |
| let len = length - needed; |
| let left = len & 0x7; |
| |
| let mut i = needed; |
| while i < len - left { |
| let mi = unsafe { load_int_le!(msg, i, u64) }; |
| |
| self.state.v3 ^= mi; |
| Sip24Rounds::c_rounds(&mut self.state); |
| self.state.v0 ^= mi; |
| |
| i += 8; |
| } |
| |
| self.tail = unsafe { u8to64_le(msg, i, left) }; |
| self.ntail = left; |
| } |
| |
| fn finish(&self) -> u64 { |
| panic!("SipHasher128 cannot provide valid 64 bit hashes") |
| } |
| } |
| |
| #[derive(Debug, Clone, Default)] |
| struct Sip24Rounds; |
| |
| impl Sip24Rounds { |
| #[inline] |
| fn c_rounds(state: &mut State) { |
| compress!(state); |
| compress!(state); |
| } |
| |
| #[inline] |
| fn d_rounds(state: &mut State) { |
| compress!(state); |
| compress!(state); |
| compress!(state); |
| compress!(state); |
| } |
| } |