add libcore from 2016-04-11 nightly

1 files changed, 239 insertions, 0 deletions

diff --git a/libcore/hash/sip.rs b/libcore/hash/sip.rs
new file mode 100644
index 0000000..fd1dab7
--- /dev/null
+++ b/libcore/hash/sip.rs
@@ -0,0 +1,239 @@
+// 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 2-4.
+
+use prelude::v1::*;
+
+use ptr;
+use super::Hasher;
+
+/// 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_.
+#[derive(Debug)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct SipHasher {
+    k0: u64,
+    k1: u64,
+    length: usize, // how many bytes we've processed
+    // 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, // hash state
+    v2: u64,
+    v1: u64,
+    v3: u64,
+    tail: u64, // unprocessed bytes le
+    ntail: usize, // how many bytes in tail are valid
+}
+
+// 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($b))))
+}
+
+macro_rules! compress {
+    ($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 {
+        let mut state = SipHasher {
+            k0: key0,
+            k1: key1,
+            length: 0,
+            v0: 0,
+            v1: 0,
+            v2: 0,
+            v3: 0,
+            tail: 0,
+            ntail: 0,
+        };
+        state.reset();
+        state
+    }
+
+    #[inline]
+    fn reset(&mut self) {
+        self.length = 0;
+        self.v0 = self.k0 ^ 0x736f6d6570736575;
+        self.v1 = self.k1 ^ 0x646f72616e646f6d;
+        self.v2 = self.k0 ^ 0x6c7967656e657261;
+        self.v3 = self.k1 ^ 0x7465646279746573;
+        self.ntail = 0;
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Hasher for SipHasher {
+    #[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.v3 ^= m;
+            compress!(self.v0, self.v1, self.v2, self.v3);
+            compress!(self.v0, self.v1, self.v2, self.v3);
+            self.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.v3 ^= mi;
+            compress!(self.v0, self.v1, self.v2, self.v3);
+            compress!(self.v0, self.v1, self.v2, self.v3);
+            self.v0 ^= mi;
+
+            i += 8;
+        }
+
+        self.tail = u8to64_le!(msg, i, left);
+        self.ntail = left;
+    }
+
+    #[inline]
+    fn finish(&self) -> u64 {
+        let mut v0 = self.v0;
+        let mut v1 = self.v1;
+        let mut v2 = self.v2;
+        let mut v3 = self.v3;
+
+        let b: u64 = ((self.length as u64 & 0xff) << 56) | self.tail;
+
+        v3 ^= b;
+        compress!(v0, v1, v2, v3);
+        compress!(v0, v1, v2, v3);
+        v0 ^= b;
+
+        v2 ^= 0xff;
+        compress!(v0, v1, v2, v3);
+        compress!(v0, v1, v2, v3);
+        compress!(v0, v1, v2, v3);
+        compress!(v0, v1, v2, v3);
+
+        v0 ^ v1 ^ v2 ^ v3
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Clone for SipHasher {
+    #[inline]
+    fn clone(&self) -> SipHasher {
+        SipHasher {
+            k0: self.k0,
+            k1: self.k1,
+            length: self.length,
+            v0: self.v0,
+            v1: self.v1,
+            v2: self.v2,
+            v3: self.v3,
+            tail: self.tail,
+            ntail: self.ntail,
+        }
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Default for SipHasher {
+    fn default() -> SipHasher {
+        SipHasher::new()
+    }
+}