src/libcore/hash/sip.rs - third_party/rust - Git at Google

 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 //! An implementation of SipHash.

 use prelude::v1::*;

 use marker::PhantomData;
 use ptr;

 /// An implementation of SipHash 1-3.
 ///
 /// See: https://131002.net/siphash/
 #[unstable(feature = "sip_hash_13", issue = "34767")]
 #[derive(Debug, Clone, Default)]
 pub struct SipHasher13 {
     hasher: Hasher<Sip13Rounds>,
 }

 /// An implementation of SipHash 2-4.
 ///
 /// See: https://131002.net/siphash/
 #[unstable(feature = "sip_hash_13", issue = "34767")]
 #[derive(Debug, Clone, Default)]
 pub struct SipHasher24 {
     hasher: Hasher<Sip24Rounds>,
 }

 /// An implementation of SipHash 2-4.
 ///
 /// See: https://131002.net/siphash/
 ///
 /// This is currently the default hashing function used by standard library
 /// (eg. `collections::HashMap` uses it by default).
 ///
 /// SipHash is a general-purpose hashing function: it runs at a good
 /// speed (competitive with Spooky and City) and permits strong _keyed_
 /// hashing. This lets you key your hashtables from a strong RNG, such as
 /// [`rand::os::OsRng`](https://doc.rust-lang.org/rand/rand/os/struct.OsRng.html).
 ///
 /// Although the SipHash algorithm is considered to be generally strong,
 /// it is not intended for cryptographic purposes. As such, all
 /// cryptographic uses of this implementation are _strongly discouraged_.
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Debug, Clone, Default)]
 pub struct SipHasher(SipHasher24);

 #[derive(Debug)]
 struct Hasher<S: Sip> {
     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
     _marker: PhantomData<S>,
 }

 #[derive(Debug, Clone, Copy)]
 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,
 }

 // sadly, these macro definitions can't appear later,
 // because they're needed in the following defs;
 // this design could be improved.

 macro_rules! u8to64_le {
     ($buf:expr, $i:expr) =>
     ($buf[0+$i] as u64 |
      ($buf[1+$i] as u64) << 8 |
      ($buf[2+$i] as u64) << 16 |
      ($buf[3+$i] as u64) << 24 |
      ($buf[4+$i] as u64) << 32 |
      ($buf[5+$i] as u64) << 40 |
      ($buf[6+$i] as u64) << 48 |
      ($buf[7+$i] as u64) << 56);
     ($buf:expr, $i:expr, $len:expr) =>
     ({
         let mut t = 0;
         let mut out = 0;
         while t < $len {
             out |= ($buf[t+$i] as u64) << t*8;
             t += 1;
         }
         out
     });
 }

 /// Load a full u64 word from a byte stream, in LE order. Use
 /// `copy_nonoverlapping` to let the compiler generate the most efficient way
 /// to load u64 from a possibly unaligned address.
 ///
 /// Unsafe because: unchecked indexing at i..i+8
 #[inline]
 unsafe fn load_u64_le(buf: &[u8], i: usize) -> u64 {
     debug_assert!(i + 8 <= buf.len());
     let mut data = 0u64;
     ptr::copy_nonoverlapping(buf.get_unchecked(i), &mut data as *mut _ as *mut u8, 8);
     data.to_le()
 }

 macro_rules! rotl {
     ($x:expr, $b:expr) =>
     (($x << $b) | ($x >> (64_i32.wrapping_sub($b))))
 }

 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); $v1 = rotl!($v1, 13); $v1 ^= $v0;
         $v0 = rotl!($v0, 32);
         $v2 = $v2.wrapping_add($v3); $v3 = rotl!($v3, 16); $v3 ^= $v2;
         $v0 = $v0.wrapping_add($v3); $v3 = rotl!($v3, 21); $v3 ^= $v0;
         $v2 = $v2.wrapping_add($v1); $v1 = rotl!($v1, 17); $v1 ^= $v2;
         $v2 = rotl!($v2, 32);
     });
 }

 impl SipHasher {
     /// Creates a new `SipHasher` with the two initial keys set to 0.
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new() -> SipHasher {
         SipHasher::new_with_keys(0, 0)
     }

     /// Creates a `SipHasher` that is keyed off the provided keys.
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
         SipHasher(SipHasher24::new_with_keys(key0, key1))
     }
 }


 impl SipHasher13 {
     /// Creates a new `SipHasher13` with the two initial keys set to 0.
     #[inline]
     #[unstable(feature = "sip_hash_13", issue = "34767")]
     pub fn new() -> SipHasher13 {
         SipHasher13::new_with_keys(0, 0)
     }

     /// Creates a `SipHasher13` that is keyed off the provided keys.
     #[inline]
     #[unstable(feature = "sip_hash_13", issue = "34767")]
     pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher13 {
         SipHasher13 {
             hasher: Hasher::new_with_keys(key0, key1)
         }
     }
 }

 impl SipHasher24 {
     /// Creates a new `SipHasher24` with the two initial keys set to 0.
     #[inline]
     #[unstable(feature = "sip_hash_13", issue = "34767")]
     pub fn new() -> SipHasher24 {
         SipHasher24::new_with_keys(0, 0)
     }

     /// Creates a `SipHasher24` that is keyed off the provided keys.
     #[inline]
     #[unstable(feature = "sip_hash_13", issue = "34767")]
     pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher24 {
         SipHasher24 {
             hasher: Hasher::new_with_keys(key0, key1)
         }
     }
 }

 impl<S: Sip> Hasher<S> {
     #[inline]
     fn new_with_keys(key0: u64, key1: u64) -> Hasher<S> {
         let mut state = Hasher {
             k0: key0,
             k1: key1,
             length: 0,
             state: State {
                 v0: 0,
                 v1: 0,
                 v2: 0,
                 v3: 0,
             },
             tail: 0,
             ntail: 0,
             _marker: PhantomData,
         };
         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;
     }
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl super::Hasher for SipHasher {
     #[inline]
     fn write(&mut self, msg: &[u8]) {
         self.0.write(msg)
     }

     #[inline]
     fn finish(&self) -> u64 {
         self.0.finish()
     }
 }

 #[unstable(feature = "sip_hash_13", issue = "34767")]
 impl super::Hasher for SipHasher13 {
     #[inline]
     fn write(&mut self, msg: &[u8]) {
         self.hasher.write(msg)
     }

     #[inline]
     fn finish(&self) -> u64 {
         self.hasher.finish()
     }
 }

 #[unstable(feature = "sip_hash_13", issue = "34767")]
 impl super::Hasher for SipHasher24 {
     #[inline]
     fn write(&mut self, msg: &[u8]) {
         self.hasher.write(msg)
     }

     #[inline]
     fn finish(&self) -> u64 {
         self.hasher.finish()
     }
 }

 impl<S: Sip> super::Hasher for Hasher<S> {
     #[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;
             if length < needed {
                 self.tail |= u8to64_le!(msg, 0, length) << 8 * self.ntail;
                 self.ntail += length;
                 return
             }

             let m = self.tail | u8to64_le!(msg, 0, needed) << 8 * self.ntail;

             self.state.v3 ^= m;
             S::c_rounds(&mut self.state);
             self.state.v0 ^= m;

             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_u64_le(msg, i) };

             self.state.v3 ^= mi;
             S::c_rounds(&mut self.state);
             self.state.v0 ^= mi;

             i += 8;
         }

         self.tail = u8to64_le!(msg, i, left);
         self.ntail = left;
     }

     #[inline]
     fn finish(&self) -> u64 {
         let mut state = self.state;

         let b: u64 = ((self.length as u64 & 0xff) << 56) | self.tail;

         state.v3 ^= b;
         S::c_rounds(&mut state);
         state.v0 ^= b;

         state.v2 ^= 0xff;
         S::d_rounds(&mut state);

         state.v0 ^ state.v1 ^ state.v2 ^ state.v3
     }
 }

 impl<S: Sip> Clone for Hasher<S> {
     #[inline]
     fn clone(&self) -> Hasher<S> {
         Hasher {
             k0: self.k0,
             k1: self.k1,
             length: self.length,
             state: self.state,
             tail: self.tail,
             ntail: self.ntail,
             _marker: self._marker,
         }
     }
 }

 impl<S: Sip> Default for Hasher<S> {
     #[inline]
     fn default() -> Hasher<S> {
         Hasher::new_with_keys(0, 0)
     }
 }

 #[doc(hidden)]
 trait Sip {
     fn c_rounds(&mut State);
     fn d_rounds(&mut State);
 }

 #[derive(Debug, Clone, Default)]
 struct Sip13Rounds;

 impl Sip for Sip13Rounds {
     #[inline]
     fn c_rounds(state: &mut State) {
         compress!(state);
     }

     #[inline]
     fn d_rounds(state: &mut State) {
         compress!(state);
         compress!(state);
         compress!(state);
     }
 }

 #[derive(Debug, Clone, Default)]
 struct Sip24Rounds;

 impl Sip for 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);
     }
 }
	// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	//! An implementation of SipHash.

	use prelude::v1::*;

	use marker::PhantomData;
	use ptr;

	/// An implementation of SipHash 1-3.
	///
	/// See: https://131002.net/siphash/
	#[unstable(feature = "sip_hash_13", issue = "34767")]
	#[derive(Debug, Clone, Default)]
	pub struct SipHasher13 {
	hasher: Hasher<Sip13Rounds>,
	}

	/// An implementation of SipHash 2-4.
	///
	/// See: https://131002.net/siphash/
	#[unstable(feature = "sip_hash_13", issue = "34767")]
	#[derive(Debug, Clone, Default)]
	pub struct SipHasher24 {
	hasher: Hasher<Sip24Rounds>,
	}

	/// An implementation of SipHash 2-4.
	///
	/// See: https://131002.net/siphash/
	///
	/// This is currently the default hashing function used by standard library
	/// (eg. `collections::HashMap` uses it by default).
	///
	/// SipHash is a general-purpose hashing function: it runs at a good
	/// speed (competitive with Spooky and City) and permits strong _keyed_
	/// hashing. This lets you key your hashtables from a strong RNG, such as
	/// [`rand::os::OsRng`](https://doc.rust-lang.org/rand/rand/os/struct.OsRng.html).
	///
	/// Although the SipHash algorithm is considered to be generally strong,
	/// it is not intended for cryptographic purposes. As such, all
	/// cryptographic uses of this implementation are _strongly discouraged_.
	#[stable(feature = "rust1", since = "1.0.0")]
	#[derive(Debug, Clone, Default)]
	pub struct SipHasher(SipHasher24);

	#[derive(Debug)]
	struct Hasher<S: Sip> {
	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
	_marker: PhantomData<S>,
	}

	#[derive(Debug, Clone, Copy)]
	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,
	}

	// sadly, these macro definitions can't appear later,
	// because they're needed in the following defs;
	// this design could be improved.

	macro_rules! u8to64_le {
	($buf:expr, $i:expr) =>
	($buf[0+$i] as u64 \|
	($buf[1+$i] as u64) << 8 \|
	($buf[2+$i] as u64) << 16 \|
	($buf[3+$i] as u64) << 24 \|
	($buf[4+$i] as u64) << 32 \|
	($buf[5+$i] as u64) << 40 \|
	($buf[6+$i] as u64) << 48 \|
	($buf[7+$i] as u64) << 56);
	($buf:expr, $i:expr, $len:expr) =>
	({
	let mut t = 0;
	let mut out = 0;
	while t < $len {
	out \|= ($buf[t+$i] as u64) << t*8;
	t += 1;
	}
	out
	});
	}

	/// Load a full u64 word from a byte stream, in LE order. Use
	/// `copy_nonoverlapping` to let the compiler generate the most efficient way
	/// to load u64 from a possibly unaligned address.
	///
	/// Unsafe because: unchecked indexing at i..i+8
	#[inline]
	unsafe fn load_u64_le(buf: &[u8], i: usize) -> u64 {
	debug_assert!(i + 8 <= buf.len());
	let mut data = 0u64;
	ptr::copy_nonoverlapping(buf.get_unchecked(i), &mut data as mut _ as mut u8, 8);
	data.to_le()
	}

	macro_rules! rotl {
	($x:expr, $b:expr) =>
	(($x << $b) \| ($x >> (64_i32.wrapping_sub($b))))
	}

	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); $v1 = rotl!($v1, 13); $v1 ^= $v0;
	$v0 = rotl!($v0, 32);
	$v2 = $v2.wrapping_add($v3); $v3 = rotl!($v3, 16); $v3 ^= $v2;
	$v0 = $v0.wrapping_add($v3); $v3 = rotl!($v3, 21); $v3 ^= $v0;
	$v2 = $v2.wrapping_add($v1); $v1 = rotl!($v1, 17); $v1 ^= $v2;
	$v2 = rotl!($v2, 32);
	});
	}

	impl SipHasher {
	/// Creates a new `SipHasher` with the two initial keys set to 0.
	#[inline]
	#[stable(feature = "rust1", since = "1.0.0")]
	pub fn new() -> SipHasher {
	SipHasher::new_with_keys(0, 0)
	}

	/// Creates a `SipHasher` that is keyed off the provided keys.
	#[inline]
	#[stable(feature = "rust1", since = "1.0.0")]
	pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
	SipHasher(SipHasher24::new_with_keys(key0, key1))
	}
	}


	impl SipHasher13 {
	/// Creates a new `SipHasher13` with the two initial keys set to 0.
	#[inline]
	#[unstable(feature = "sip_hash_13", issue = "34767")]
	pub fn new() -> SipHasher13 {
	SipHasher13::new_with_keys(0, 0)
	}

	/// Creates a `SipHasher13` that is keyed off the provided keys.
	#[inline]
	#[unstable(feature = "sip_hash_13", issue = "34767")]
	pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher13 {
	SipHasher13 {
	hasher: Hasher::new_with_keys(key0, key1)
	}
	}
	}

	impl SipHasher24 {
	/// Creates a new `SipHasher24` with the two initial keys set to 0.
	#[inline]
	#[unstable(feature = "sip_hash_13", issue = "34767")]
	pub fn new() -> SipHasher24 {
	SipHasher24::new_with_keys(0, 0)
	}

	/// Creates a `SipHasher24` that is keyed off the provided keys.
	#[inline]
	#[unstable(feature = "sip_hash_13", issue = "34767")]
	pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher24 {
	SipHasher24 {
	hasher: Hasher::new_with_keys(key0, key1)
	}
	}
	}

	impl<S: Sip> Hasher<S> {
	#[inline]
	fn new_with_keys(key0: u64, key1: u64) -> Hasher<S> {
	let mut state = Hasher {
	k0: key0,
	k1: key1,
	length: 0,
	state: State {
	v0: 0,
	v1: 0,
	v2: 0,
	v3: 0,
	},
	tail: 0,
	ntail: 0,
	_marker: PhantomData,
	};
	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;
	}
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl super::Hasher for SipHasher {
	#[inline]
	fn write(&mut self, msg: &[u8]) {
	self.0.write(msg)
	}

	#[inline]
	fn finish(&self) -> u64 {
	self.0.finish()
	}
	}

	#[unstable(feature = "sip_hash_13", issue = "34767")]
	impl super::Hasher for SipHasher13 {
	#[inline]
	fn write(&mut self, msg: &[u8]) {
	self.hasher.write(msg)
	}

	#[inline]
	fn finish(&self) -> u64 {
	self.hasher.finish()
	}
	}

	#[unstable(feature = "sip_hash_13", issue = "34767")]
	impl super::Hasher for SipHasher24 {
	#[inline]
	fn write(&mut self, msg: &[u8]) {
	self.hasher.write(msg)
	}

	#[inline]
	fn finish(&self) -> u64 {
	self.hasher.finish()
	}
	}

	impl<S: Sip> super::Hasher for Hasher<S> {
	#[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;
	if length < needed {
	self.tail \|= u8to64_le!(msg, 0, length) << 8 * self.ntail;
	self.ntail += length;
	return
	}

	let m = self.tail \| u8to64_le!(msg, 0, needed) << 8 * self.ntail;

	self.state.v3 ^= m;
	S::c_rounds(&mut self.state);
	self.state.v0 ^= m;

	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_u64_le(msg, i) };

	self.state.v3 ^= mi;
	S::c_rounds(&mut self.state);
	self.state.v0 ^= mi;

	i += 8;
	}

	self.tail = u8to64_le!(msg, i, left);
	self.ntail = left;
	}

	#[inline]
	fn finish(&self) -> u64 {
	let mut state = self.state;

	let b: u64 = ((self.length as u64 & 0xff) << 56) \| self.tail;

	state.v3 ^= b;
	S::c_rounds(&mut state);
	state.v0 ^= b;

	state.v2 ^= 0xff;
	S::d_rounds(&mut state);

	state.v0 ^ state.v1 ^ state.v2 ^ state.v3
	}
	}

	impl<S: Sip> Clone for Hasher<S> {
	#[inline]
	fn clone(&self) -> Hasher<S> {
	Hasher {
	k0: self.k0,
	k1: self.k1,
	length: self.length,
	state: self.state,
	tail: self.tail,
	ntail: self.ntail,
	_marker: self._marker,
	}
	}
	}

	impl<S: Sip> Default for Hasher<S> {
	#[inline]
	fn default() -> Hasher<S> {
	Hasher::new_with_keys(0, 0)
	}
	}

	#[doc(hidden)]
	trait Sip {
	fn c_rounds(&mut State);
	fn d_rounds(&mut State);
	}

	#[derive(Debug, Clone, Default)]
	struct Sip13Rounds;

	impl Sip for Sip13Rounds {
	#[inline]
	fn c_rounds(state: &mut State) {
	compress!(state);
	}

	#[inline]
	fn d_rounds(state: &mut State) {
	compress!(state);
	compress!(state);
	compress!(state);
	}
	}

	#[derive(Debug, Clone, Default)]
	struct Sip24Rounds;

	impl Sip for 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);
	}
	}