4 files changed, 167 insertions, 10 deletions
diff --git a/src/libcore/hash/sip.rs b/src/libcore/hash/sip.rs
index 39bcbacdff1..df0008c500b 100644
--- a/src/libcore/hash/sip.rs
+++ b/src/libcore/hash/sip.rs
@@ -14,7 +14,7 @@
 
 use prelude::*;
 use default::Default;
-
+use num::wrapping::WrappingOps;
 use super::Hasher;
 
 /// An implementation of SipHash 2-4.
@@ -71,17 +71,17 @@ macro_rules! u8to64_le {
 
 macro_rules! rotl {
     ($x:expr, $b:expr) =>
-    (($x << $b) | ($x >> (64 - $b)))
+    (($x << $b) | ($x >> (64.wrapping_sub($b))))
 }
 
 macro_rules! compress {
     ($v0:expr, $v1:expr, $v2:expr, $v3:expr) =>
     ({
-        $v0 += $v1; $v1 = rotl!($v1, 13); $v1 ^= $v0;
+        $v0 = $v0.wrapping_add($v1); $v1 = rotl!($v1, 13); $v1 ^= $v0;
         $v0 = rotl!($v0, 32);
-        $v2 += $v3; $v3 = rotl!($v3, 16); $v3 ^= $v2;
-        $v0 += $v3; $v3 = rotl!($v3, 21); $v3 ^= $v0;
-        $v2 += $v1; $v1 = rotl!($v1, 17); $v1 ^= $v2;
+        $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);
     })
 }
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index d77a1eb4203..3ed059520b1 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -30,6 +30,9 @@ use option::Option::{self, Some, None};
 use result::Result::{self, Ok, Err};
 use str::{FromStr, StrExt};
 
+#[unstable(feature = "core", reason = "may be removed or relocated")]
+pub mod wrapping;
+
 /// A built-in signed or unsigned integer.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Int
diff --git a/src/libcore/num/wrapping.rs b/src/libcore/num/wrapping.rs
new file mode 100644
index 00000000000..30478a8f09f
--- /dev/null
+++ b/src/libcore/num/wrapping.rs
@@ -0,0 +1,153 @@
+// Copyright 2014 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.
+#![allow(missing_docs)]
+
+use ops::*;
+
+#[cfg(not(stage0))]
+use intrinsics::{overflowing_add, overflowing_sub, overflowing_mul};
+
+pub trait WrappingOps {
+    fn wrapping_add(self, rhs: Self) -> Self;
+    fn wrapping_sub(self, rhs: Self) -> Self;
+    fn wrapping_mul(self, rhs: Self) -> Self;
+}
+
+#[cfg(not(stage0))]
+macro_rules! wrapping_impl {
+    ($($t:ty)*) => ($(
+        impl WrappingOps for $t {
+            #[inline(always)]
+            fn wrapping_add(self, rhs: $t) -> $t {
+                unsafe {
+                    overflowing_add(self, rhs)
+                }
+            }
+            #[inline(always)]
+            fn wrapping_sub(self, rhs: $t) -> $t {
+                unsafe {
+                    overflowing_sub(self, rhs)
+                }
+            }
+            #[inline(always)]
+            fn wrapping_mul(self, rhs: $t) -> $t {
+                unsafe {
+                    overflowing_mul(self, rhs)
+                }
+            }
+        }
+    )*)
+}
+
+#[cfg(stage0)]
+macro_rules! wrapping_impl {
+    ($($t:ty)*) => ($(
+        impl WrappingOps for $t {
+            #[inline(always)]
+            fn wrapping_add(self, rhs: $t) -> $t {
+                self + rhs
+            }
+            #[inline(always)]
+            fn wrapping_sub(self, rhs: $t) -> $t {
+                self - rhs
+            }
+            #[inline(always)]
+            fn wrapping_mul(self, rhs: $t) -> $t {
+                self * rhs
+            }
+        }
+    )*)
+}
+
+wrapping_impl! { uint u8 u16 u32 u64 int i8 i16 i32 i64 }
+
+#[unstable(feature = "core", reason = "may be removed, renamed, or relocated")]
+#[derive(PartialEq,Eq,PartialOrd,Ord,Clone,Copy)]
+pub struct Wrapping<T>(pub T);
+
+impl<T:WrappingOps> Add for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn add(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0.wrapping_add(other.0))
+    }
+}
+
+impl<T:WrappingOps> Sub for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn sub(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0.wrapping_sub(other.0))
+    }
+}
+
+impl<T:WrappingOps> Mul for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn mul(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0.wrapping_mul(other.0))
+    }
+}
+
+impl<T:WrappingOps+Not<Output=T>> Not for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    fn not(self) -> Wrapping<T> {
+        Wrapping(!self.0)
+    }
+}
+
+impl<T:WrappingOps+BitXor<Output=T>> BitXor for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn bitxor(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0 ^ other.0)
+    }
+}
+
+impl<T:WrappingOps+BitOr<Output=T>> BitOr for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn bitor(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0 | other.0)
+    }
+}
+
+impl<T:WrappingOps+BitAnd<Output=T>> BitAnd for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn bitand(self, other: Wrapping<T>) -> Wrapping<T> {
+        Wrapping(self.0 & other.0)
+    }
+}
+
+impl<T:WrappingOps+Shl<uint,Output=T>> Shl<uint> for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn shl(self, other: uint) -> Wrapping<T> {
+        Wrapping(self.0 << other)
+    }
+}
+
+impl<T:WrappingOps+Shr<uint,Output=T>> Shr<uint> for Wrapping<T> {
+    type Output = Wrapping<T>;
+
+    #[inline(always)]
+    fn shr(self, other: uint) -> Wrapping<T> {
+        Wrapping(self.0 >> other)
+    }
+}
diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs
index b354116993c..a7a06906409 100644
--- a/src/libcore/str/mod.rs
+++ b/src/libcore/str/mod.rs
@@ -830,6 +830,7 @@ impl TwoWaySearcher {
     #[inline]
     #[allow(dead_code)]
     fn maximal_suffix(arr: &[u8], reversed: bool) -> (usize, usize) {
+        use num::wrapping::WrappingOps;
         let mut left = -1; // Corresponds to i in the paper
         let mut right = 0; // Corresponds to j in the paper
         let mut offset = 1; // Corresponds to k in the paper
@@ -839,17 +840,17 @@ impl TwoWaySearcher {
             let a;
             let b;
             if reversed {
-                a = arr[left + offset];
+                a = arr[left.wrapping_add(offset)];
                 b = arr[right + offset];
             } else {
                 a = arr[right + offset];
-                b = arr[left + offset];
+                b = arr[left.wrapping_add(offset)];
             }
             if a < b {
                 // Suffix is smaller, period is entire prefix so far.
                 right += offset;
                 offset = 1;
-                period = right - left;
+                period = right.wrapping_sub(left);
             } else if a == b {
                 // Advance through repetition of the current period.
                 if offset == period {
@@ -866,7 +867,7 @@ impl TwoWaySearcher {
                 period = 1;
             }
         }
-        (left + 1, period)
+        (left.wrapping_add(1), period)
     }
 }