compiler/rustc_data_structures/src/sip128.rs - third_party/rust - Git at Google

 //! This is a copy of `core::hash::sip` adapted to providing 128 bit hashes.

 use std::cmp;
 use std::hash::Hasher;
 use std::mem;
 use std::ptr;

 #[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 a u64 using up to 7 bytes of a byte slice. It looks clumsy but the
 /// `copy_nonoverlapping` calls that occur (via `load_int_le!`) all have fixed
 /// sizes and avoid calling `memcpy`, which is good for speed.
 ///
 /// 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 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;
     }

     // A specialized write function for values with size <= 8.
     //
     // The hashing of multi-byte integers depends on endianness. E.g.:
     // - little-endian: `write_u32(0xDDCCBBAA)` == `write([0xAA, 0xBB, 0xCC, 0xDD])`
     // - big-endian:    `write_u32(0xDDCCBBAA)` == `write([0xDD, 0xCC, 0xBB, 0xAA])`
     //
     // This function does the right thing for little-endian hardware. On
     // big-endian hardware `x` must be byte-swapped first to give the right
     // behaviour. After any byte-swapping, the input must be zero-extended to
     // 64-bits. The caller is responsible for the byte-swapping and
     // zero-extension.
     #[inline]
     fn short_write<T>(&mut self, _x: T, x: u64) {
         let size = mem::size_of::<T>();
         self.length += size;

         // The original number must be zero-extended, not sign-extended.
         debug_assert!(if size < 8 { x >> (8 * size) == 0 } else { true });

         // The number of bytes needed to fill `self.tail`.
         let needed = 8 - self.ntail;

         // SipHash parses the input stream as 8-byte little-endian integers.
         // Inputs are put into `self.tail` until 8 bytes of data have been
         // collected, and then that word is processed.
         //
         // For example, imagine that `self.tail` is 0x0000_00EE_DDCC_BBAA,
         // `self.ntail` is 5 (because 5 bytes have been put into `self.tail`),
         // and `needed` is therefore 3.
         //
         // - Scenario 1, `self.write_u8(0xFF)`: we have already zero-extended
         //   the input to 0x0000_0000_0000_00FF. We now left-shift it five
         //   bytes, giving 0x0000_FF00_0000_0000. We then bitwise-OR that value
         //   into `self.tail`, resulting in 0x0000_FFEE_DDCC_BBAA.
         //   (Zero-extension of the original input is critical in this scenario
         //   because we don't want the high two bytes of `self.tail` to be
         //   touched by the bitwise-OR.) `self.tail` is not yet full, so we
         //   return early, after updating `self.ntail` to 6.
         //
         // - Scenario 2, `self.write_u32(0xIIHH_GGFF)`: we have already
         //   zero-extended the input to 0x0000_0000_IIHH_GGFF. We now
         //   left-shift it five bytes, giving 0xHHGG_FF00_0000_0000. We then
         //   bitwise-OR that value into `self.tail`, resulting in
         //   0xHHGG_FFEE_DDCC_BBAA. `self.tail` is now full, and we can use it
         //   to update `self.state`. (As mentioned above, this assumes a
         //   little-endian machine; on a big-endian machine we would have
         //   byte-swapped 0xIIHH_GGFF in the caller, giving 0xFFGG_HHII, and we
         //   would then end up bitwise-ORing 0xGGHH_II00_0000_0000 into
         //   `self.tail`).
         //
         self.tail |= x << (8 * self.ntail);
         if size < needed {
             self.ntail += size;
             return;
         }

         // `self.tail` is full, process it.
         self.state.v3 ^= self.tail;
         Sip24Rounds::c_rounds(&mut self.state);
         self.state.v0 ^= self.tail;

         // Continuing scenario 2: we have one byte left over from the input. We
         // set `self.ntail` to 1 and `self.tail` to `0x0000_0000_IIHH_GGFF >>
         // 8*3`, which is 0x0000_0000_0000_00II. (Or on a big-endian machine
         // the prior byte-swapping would leave us with 0x0000_0000_0000_00FF.)
         //
         // The `if` is needed to avoid shifting by 64 bits, which Rust
         // complains about.
         self.ntail = size - needed;
         self.tail = if needed < 8 { x >> (8 * needed) } else { 0 };
     }

     #[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(i, i as u64);
     }

     #[inline]
     fn write_u16(&mut self, i: u16) {
         self.short_write(i, i.to_le() as u64);
     }

     #[inline]
     fn write_u32(&mut self, i: u32) {
         self.short_write(i, i.to_le() as u64);
     }

     #[inline]
     fn write_u64(&mut self, i: u64) {
         self.short_write(i, i.to_le() as u64);
     }

     #[inline]
     fn write_usize(&mut self, i: usize) {
         self.short_write(i, i.to_le() as u64);
     }

     #[inline]
     fn write_i8(&mut self, i: i8) {
         self.short_write(i, i as u8 as u64);
     }

     #[inline]
     fn write_i16(&mut self, i: i16) {
         self.short_write(i, (i as u16).to_le() as u64);
     }

     #[inline]
     fn write_i32(&mut self, i: i32) {
         self.short_write(i, (i as u32).to_le() as u64);
     }

     #[inline]
     fn write_i64(&mut self, i: i64) {
         self.short_write(i, (i as u64).to_le() as u64);
     }

     #[inline]
     fn write_isize(&mut self, i: isize) {
         self.short_write(i, (i as usize).to_le() as u64);
     }

     #[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);
     }
 }
	//! This is a copy of `core::hash::sip` adapted to providing 128 bit hashes.

	use std::cmp;
	use std::hash::Hasher;
	use std::mem;
	use std::ptr;

	#[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 a u64 using up to 7 bytes of a byte slice. It looks clumsy but the
	/// `copy_nonoverlapping` calls that occur (via `load_int_le!`) all have fixed
	/// sizes and avoid calling `memcpy`, which is good for speed.
	///
	/// 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 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;
	}

	// A specialized write function for values with size <= 8.
	//
	// The hashing of multi-byte integers depends on endianness. E.g.:
	// - little-endian: `write_u32(0xDDCCBBAA)` == `write([0xAA, 0xBB, 0xCC, 0xDD])`
	// - big-endian: `write_u32(0xDDCCBBAA)` == `write([0xDD, 0xCC, 0xBB, 0xAA])`
	//
	// This function does the right thing for little-endian hardware. On
	// big-endian hardware `x` must be byte-swapped first to give the right
	// behaviour. After any byte-swapping, the input must be zero-extended to
	// 64-bits. The caller is responsible for the byte-swapping and
	// zero-extension.
	#[inline]
	fn short_write<T>(&mut self, _x: T, x: u64) {
	let size = mem::size_of::<T>();
	self.length += size;

	// The original number must be zero-extended, not sign-extended.
	debug_assert!(if size < 8 { x >> (8 * size) == 0 } else { true });

	// The number of bytes needed to fill `self.tail`.
	let needed = 8 - self.ntail;

	// SipHash parses the input stream as 8-byte little-endian integers.
	// Inputs are put into `self.tail` until 8 bytes of data have been
	// collected, and then that word is processed.
	//
	// For example, imagine that `self.tail` is 0x0000_00EE_DDCC_BBAA,
	// `self.ntail` is 5 (because 5 bytes have been put into `self.tail`),
	// and `needed` is therefore 3.
	//
	// - Scenario 1, `self.write_u8(0xFF)`: we have already zero-extended
	// the input to 0x0000_0000_0000_00FF. We now left-shift it five
	// bytes, giving 0x0000_FF00_0000_0000. We then bitwise-OR that value
	// into `self.tail`, resulting in 0x0000_FFEE_DDCC_BBAA.
	// (Zero-extension of the original input is critical in this scenario
	// because we don't want the high two bytes of `self.tail` to be
	// touched by the bitwise-OR.) `self.tail` is not yet full, so we
	// return early, after updating `self.ntail` to 6.
	//
	// - Scenario 2, `self.write_u32(0xIIHH_GGFF)`: we have already
	// zero-extended the input to 0x0000_0000_IIHH_GGFF. We now
	// left-shift it five bytes, giving 0xHHGG_FF00_0000_0000. We then
	// bitwise-OR that value into `self.tail`, resulting in
	// 0xHHGG_FFEE_DDCC_BBAA. `self.tail` is now full, and we can use it
	// to update `self.state`. (As mentioned above, this assumes a
	// little-endian machine; on a big-endian machine we would have
	// byte-swapped 0xIIHH_GGFF in the caller, giving 0xFFGG_HHII, and we
	// would then end up bitwise-ORing 0xGGHH_II00_0000_0000 into
	// `self.tail`).
	//
	self.tail \|= x << (8 * self.ntail);
	if size < needed {
	self.ntail += size;
	return;
	}

	// `self.tail` is full, process it.
	self.state.v3 ^= self.tail;
	Sip24Rounds::c_rounds(&mut self.state);
	self.state.v0 ^= self.tail;

	// Continuing scenario 2: we have one byte left over from the input. We
	// set `self.ntail` to 1 and `self.tail` to `0x0000_0000_IIHH_GGFF >>
	// 8*3`, which is 0x0000_0000_0000_00II. (Or on a big-endian machine
	// the prior byte-swapping would leave us with 0x0000_0000_0000_00FF.)
	//
	// The `if` is needed to avoid shifting by 64 bits, which Rust
	// complains about.
	self.ntail = size - needed;
	self.tail = if needed < 8 { x >> (8 * needed) } else { 0 };
	}

	#[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(i, i as u64);
	}

	#[inline]
	fn write_u16(&mut self, i: u16) {
	self.short_write(i, i.to_le() as u64);
	}

	#[inline]
	fn write_u32(&mut self, i: u32) {
	self.short_write(i, i.to_le() as u64);
	}

	#[inline]
	fn write_u64(&mut self, i: u64) {
	self.short_write(i, i.to_le() as u64);
	}

	#[inline]
	fn write_usize(&mut self, i: usize) {
	self.short_write(i, i.to_le() as u64);
	}

	#[inline]
	fn write_i8(&mut self, i: i8) {
	self.short_write(i, i as u8 as u64);
	}

	#[inline]
	fn write_i16(&mut self, i: i16) {
	self.short_write(i, (i as u16).to_le() as u64);
	}

	#[inline]
	fn write_i32(&mut self, i: i32) {
	self.short_write(i, (i as u32).to_le() as u64);
	}

	#[inline]
	fn write_i64(&mut self, i: i64) {
	self.short_write(i, (i as u64).to_le() as u64);
	}

	#[inline]
	fn write_isize(&mut self, i: isize) {
	self.short_write(i, (i as usize).to_le() as u64);
	}

	#[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);
	}
	}