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Add scalar multiplication to BigInt

This commit is contained in:
Sam Cappleman-Lynes 2017-06-29 15:46:07 +01:00
parent 79448cbdf9
commit 8b1288ea01
3 changed files with 20 additions and 12 deletions
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2
bigint/src/bigint.rs
View File

@ -485,6 +485,8 @@ impl<'a, 'b> Mul<&'b BigInt> for &'a BigInt {
} }
} }
forward_all_scalar_binop_to_val_val_commutative!(impl Mul<BigDigit> for BigInt, mul);
impl Mul<BigDigit> for BigInt { impl Mul<BigDigit> for BigInt {
type Output = BigInt; type Output = BigInt;

10
bigint/src/biguint.rs
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@ -483,9 +483,13 @@ impl Mul<BigDigit> for BigUint {
#[inline] #[inline]
fn mul(mut self, other: BigDigit) -> BigUint { fn mul(mut self, other: BigDigit) -> BigUint {
let carry = scalar_mul(&mut self.data[..], other); if other == 0 {
if carry != 0 { self.data.clear();
self.data.push(carry); } else {
let carry = scalar_mul(&mut self.data[..], other);
if carry != 0 {
self.data.push(carry);
}
} }
self self
} }

20
bigint/src/tests/bigint.rs
View File

@ -703,23 +703,25 @@ fn test_mul() {
fn test_scalar_mul() { fn test_scalar_mul() {
for elm in MUL_TRIPLES.iter() { for elm in MUL_TRIPLES.iter() {
let (a_vec, b_vec, c_vec) = *elm; let (a_vec, b_vec, c_vec) = *elm;
let a = BigInt::from_slice(Plus, a_vec);
let b = BigInt::from_slice(Plus, b_vec);
let c = BigInt::from_slice(Plus, c_vec); let c = BigInt::from_slice(Plus, c_vec);
let nc = BigInt::from_slice(Minus, c_vec); let (na, nb, nc) = (-&a, -&b, -&c);
if a_vec.len() == 1 { if a_vec.len() == 1 {
let b = BigInt::from_slice(Plus, b_vec);
let nb = BigInt::from_slice(Minus, b_vec);
let a = a_vec[0]; let a = a_vec[0];
assert!(b * a == c); assert_op!(b * a == c);
assert!(nb * a == nc); assert_op!(a * b == c);
assert_op!(nb * a == nc);
assert_op!(a * nb == nc);
} }
if b_vec.len() == 1 { if b_vec.len() == 1 {
let a = BigInt::from_slice(Plus, a_vec);
let na = BigInt::from_slice(Minus, a_vec);
let b = b_vec[0]; let b = b_vec[0];
assert!(a * b == c); assert_op!(a * b == c);
assert!(na * b == nc); assert_op!(b * a == c);
assert_op!(na * b == nc);
assert_op!(b * na == nc);
} }
} }
} }