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

 //! An implementation of SipHash.

 // ignore-tidy-undocumented-unsafe

 #![allow(deprecated)] // the types in this module are deprecated

 use crate::cmp;
 use crate::marker::PhantomData;
 use crate::mem;
 use crate::ptr;

 /// An implementation of SipHash 1-3.
 ///
 /// This is currently the default hashing function used by standard library
 /// (e.g., `collections::HashMap` uses it by default).
 ///
 /// See: <https://131002.net/siphash>
 #[unstable(feature = "hashmap_internals", issue = "none")]
 #[rustc_deprecated(
     since = "1.13.0",
     reason = "use `std::collections::hash_map::DefaultHasher` instead"
 )]
 #[derive(Debug, Clone, Default)]
 #[doc(hidden)]
 pub struct SipHasher13 {
     hasher: Hasher<Sip13Rounds>,
 }

 /// An implementation of SipHash 2-4.
 ///
 /// See: <https://131002.net/siphash/>
 #[unstable(feature = "hashmap_internals", issue = "none")]
 #[rustc_deprecated(
     since = "1.13.0",
     reason = "use `std::collections::hash_map::DefaultHasher` instead"
 )]
 #[derive(Debug, Clone, Default)]
 struct SipHasher24 {
     hasher: Hasher<Sip24Rounds>,
 }

 /// An implementation of SipHash 2-4.
 ///
 /// See: <https://131002.net/siphash/>
 ///
 /// 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")]
 #[rustc_deprecated(
     since = "1.13.0",
     reason = "use `std::collections::hash_map::DefaultHasher` instead"
 )]
 #[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)]
 #[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 = load_int_le!(buf, start + i, u32) as u64;
         i += 4;
     }
     if i + 1 < len {
         out |= (load_int_le!(buf, start + i, u16) as u64) << (i * 8);
         i += 2
     }
     if i < len {
         out |= (*buf.get_unchecked(start + i) as u64) << (i * 8);
         i += 1;
     }
     debug_assert_eq!(i, len);
     out
 }

 impl SipHasher {
     /// Creates a new `SipHasher` with the two initial keys set to 0.
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_deprecated(
         since = "1.13.0",
         reason = "use `std::collections::hash_map::DefaultHasher` instead"
     )]
     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")]
     #[rustc_deprecated(
         since = "1.13.0",
         reason = "use `std::collections::hash_map::DefaultHasher` instead"
     )]
     pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
         SipHasher(SipHasher24 { hasher: Hasher::new_with_keys(key0, key1) })
     }
 }

 impl SipHasher13 {
     /// Creates a new `SipHasher13` with the two initial keys set to 0.
     #[inline]
     #[unstable(feature = "hashmap_internals", issue = "none")]
     #[rustc_deprecated(
         since = "1.13.0",
         reason = "use `std::collections::hash_map::DefaultHasher` instead"
     )]
     pub fn new() -> SipHasher13 {
         SipHasher13::new_with_keys(0, 0)
     }

     /// Creates a `SipHasher13` that is keyed off the provided keys.
     #[inline]
     #[unstable(feature = "hashmap_internals", issue = "none")]
     #[rustc_deprecated(
         since = "1.13.0",
         reason = "use `std::collections::hash_map::DefaultHasher` instead"
     )]
     pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher13 {
         SipHasher13 { 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;
     }

     // 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;
         S::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) };
     }
 }

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

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

 #[unstable(feature = "hashmap_internals", issue = "none")]
 impl super::Hasher for SipHasher13 {
     #[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> {
     // see short_write comment for explanation
     #[inline]
     fn write_usize(&mut self, i: usize) {
         let bytes = unsafe {
             crate::slice::from_raw_parts(&i as *const usize as *const u8, mem::size_of::<usize>())
         };
         self.short_write(bytes);
     }

     // see short_write comment for explanation
     #[inline]
     fn write_u8(&mut self, i: u8) {
         self.short_write(&[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;
                 S::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;
             S::c_rounds(&mut self.state);
             self.state.v0 ^= mi;

             i += 8;
         }

         self.tail = unsafe { 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> {
     /// Creates a `Hasher<S>` with the two initial keys set to 0.
     #[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);
     }
 }
	//! An implementation of SipHash.

	// ignore-tidy-undocumented-unsafe

	#![allow(deprecated)] // the types in this module are deprecated

	use crate::cmp;
	use crate::marker::PhantomData;
	use crate::mem;
	use crate::ptr;

	/// An implementation of SipHash 1-3.
	///
	/// This is currently the default hashing function used by standard library
	/// (e.g., `collections::HashMap` uses it by default).
	///
	/// See: <https://131002.net/siphash>
	#[unstable(feature = "hashmap_internals", issue = "none")]
	#[rustc_deprecated(
	since = "1.13.0",
	reason = "use `std::collections::hash_map::DefaultHasher` instead"
	)]
	#[derive(Debug, Clone, Default)]
	#[doc(hidden)]
	pub struct SipHasher13 {
	hasher: Hasher<Sip13Rounds>,
	}

	/// An implementation of SipHash 2-4.
	///
	/// See: <https://131002.net/siphash/>
	#[unstable(feature = "hashmap_internals", issue = "none")]
	#[rustc_deprecated(
	since = "1.13.0",
	reason = "use `std::collections::hash_map::DefaultHasher` instead"
	)]
	#[derive(Debug, Clone, Default)]
	struct SipHasher24 {
	hasher: Hasher<Sip24Rounds>,
	}

	/// An implementation of SipHash 2-4.
	///
	/// See: <https://131002.net/siphash/>
	///
	/// 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")]
	#[rustc_deprecated(
	since = "1.13.0",
	reason = "use `std::collections::hash_map::DefaultHasher` instead"
	)]
	#[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)]
	#[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 = load_int_le!(buf, start + i, u32) as u64;
	i += 4;
	}
	if i + 1 < len {
	out \|= (load_int_le!(buf, start + i, u16) as u64) << (i * 8);
	i += 2
	}
	if i < len {
	out \|= (buf.get_unchecked(start + i) as u64) << (i 8);
	i += 1;
	}
	debug_assert_eq!(i, len);
	out
	}

	impl SipHasher {
	/// Creates a new `SipHasher` with the two initial keys set to 0.
	#[inline]
	#[stable(feature = "rust1", since = "1.0.0")]
	#[rustc_deprecated(
	since = "1.13.0",
	reason = "use `std::collections::hash_map::DefaultHasher` instead"
	)]
	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")]
	#[rustc_deprecated(
	since = "1.13.0",
	reason = "use `std::collections::hash_map::DefaultHasher` instead"
	)]
	pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
	SipHasher(SipHasher24 { hasher: Hasher::new_with_keys(key0, key1) })
	}
	}

	impl SipHasher13 {
	/// Creates a new `SipHasher13` with the two initial keys set to 0.
	#[inline]
	#[unstable(feature = "hashmap_internals", issue = "none")]
	#[rustc_deprecated(
	since = "1.13.0",
	reason = "use `std::collections::hash_map::DefaultHasher` instead"
	)]
	pub fn new() -> SipHasher13 {
	SipHasher13::new_with_keys(0, 0)
	}

	/// Creates a `SipHasher13` that is keyed off the provided keys.
	#[inline]
	#[unstable(feature = "hashmap_internals", issue = "none")]
	#[rustc_deprecated(
	since = "1.13.0",
	reason = "use `std::collections::hash_map::DefaultHasher` instead"
	)]
	pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher13 {
	SipHasher13 { 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;
	}

	// 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;
	S::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) };
	}
	}

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

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

	#[unstable(feature = "hashmap_internals", issue = "none")]
	impl super::Hasher for SipHasher13 {
	#[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> {
	// see short_write comment for explanation
	#[inline]
	fn write_usize(&mut self, i: usize) {
	let bytes = unsafe {
	crate::slice::from_raw_parts(&i as const usize as const u8, mem::size_of::<usize>())
	};
	self.short_write(bytes);
	}

	// see short_write comment for explanation
	#[inline]
	fn write_u8(&mut self, i: u8) {
	self.short_write(&[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;
	S::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;
	S::c_rounds(&mut self.state);
	self.state.v0 ^= mi;

	i += 8;
	}

	self.tail = unsafe { 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> {
	/// Creates a `Hasher<S>` with the two initial keys set to 0.
	#[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);
	}
	}