[BROKEN] Broken definitions of the shift operators.

src/cryptonum/mod.rs

@@ -309,6 +309,100 @@ derive_arithmetic_operators!(UCN, BitOr,  bitor,  BitOrAssign,  bitor_assign);
 derive_arithmetic_operators!(UCN, BitXor, bitxor, BitXorAssign, bitxor_assign);
 derive_arithmetic_operators!(UCN, BitAnd, bitand, BitAndAssign, bitand_assign);
 
+//------------------------------------------------------------------------------
+//
+//  Shifts
+//
+//------------------------------------------------------------------------------
+
+impl ShlAssign<u64> for UCN {
+    fn shl_assign(&mut self, rhs: u64) {
+        let mut digits = rhs / 64;
+        let bits = rhs % 64;
+        let mut carry = 0;
+
+        // ripple the bit-level shift through
+        if bits != 0 {
+            for x in self.contents.iter_mut() {
+                let new_carry = *x >> (64 - bits);
+                *x = (*x << bits) | carry;
+                carry = new_carry;
+            }
+        }
+
+        // if we pulled some stuff off the end, add it back
+        if carry != 0 {
+            self.contents.push(carry);
+        }
+
+        // add the appropriate digits on the low side
+        while digits > 0 {
+            self.contents.insert(0,0);
+            digits -= 1;
+        }
+    }
+}
+
+impl Shl<u64> for UCN {
+    type Output = UCN;
+
+    fn shl(self, rhs: u64) -> UCN {
+        let mut copy = self.clone();
+        copy.shl_assign(rhs);
+        copy
+    }
+}
+
+derive_shift_operators!(UCN, ShlAssign, Shl, shl_assign, shl, usize);
+derive_shift_operators!(UCN, ShlAssign, Shl, shl_assign, shl, u32);
+derive_shift_operators!(UCN, ShlAssign, Shl, shl_assign, shl, u16);
+derive_shift_operators!(UCN, ShlAssign, Shl, shl_assign, shl, u8);
+
+impl ShrAssign<u64> for UCN {
+    fn shr_assign(&mut self, rhs: u64) {
+        let mut digits = rhs / 64;
+        let bits = rhs % 64;
+
+        // remove the appropriate digits on the low side
+        while digits > 0 {
+            self.contents.remove(0);
+            digits -= 1;
+        }
+        // ripple the shifts over
+        let mut carry = 0;
+        let mask = !(0xFFFFFFFFFFFFFFFF << bits);
+
+        for x in self.contents.iter_mut().rev() {
+            let base = *x >> bits;
+            let (new_carry, _) = (*x & mask).overflowing_shl((64-bits) as u32);
+            *x = base | carry;
+            carry = new_carry;
+        }
+        // in this case, we just junk the extra carry bits
+    }
+}
+
+impl Shr<u64> for UCN {
+    type Output = UCN;
+
+    fn shr(self, rhs: u64) -> UCN {
+        let mut copy = self.clone();
+        copy.shr_assign(rhs);
+        copy
+    }
+}
+
+derive_shift_operators!(UCN, ShrAssign, Shr, shr_assign, shr, usize);
+derive_shift_operators!(UCN, ShrAssign, Shr, shr_assign, shr, u32);
+derive_shift_operators!(UCN, ShrAssign, Shr, shr_assign, shr, u16);
+derive_shift_operators!(UCN, ShrAssign, Shr, shr_assign, shr, u8);
+
+derive_signed_shift_operators!(UCN, usize, isize);
+derive_signed_shift_operators!(UCN, u64,   i64);
+derive_signed_shift_operators!(UCN, u32,   i32);
+derive_signed_shift_operators!(UCN, u16,   i16);
+derive_signed_shift_operators!(UCN, u8,    i8);
+
 //------------------------------------------------------------------------------
 //
 //  Tests!
@@ -475,6 +569,12 @@ mod test {
             let effs = UCN{ contents: contents };
             (&a & &effs) == a
         }
+        fn shl_identity(a: UCN) -> bool {
+            (&a << 0) == a
+        }
+        fn shr_identity(a: UCN) -> bool {
+            (&a << 0) == a
+        }
     }
 
     quickcheck! {
@@ -488,6 +588,9 @@ mod test {
             let zero = UCN{ contents: vec![] };
             (&a & &zero) == zero
         }
+        fn shl_shr_annihilate(a: UCN, b: u8) -> bool {
+            ((&a << b) >> b) == a
+        }
         fn xor_inverse(a: UCN, b: UCN) -> bool {
             ((&a ^ &b) ^ &b) == a
         }
@@ -521,4 +624,5 @@ mod test {
             (!(&a2 | &b2)) == (!a2 & !b2)
         }
     }
+
 }