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Implementing pow, overflowing_pow only for uint. Adding missing docs.

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This commit is contained in:
Tomusdrw 2016-01-16 15:45:33 +01:00
parent 40947e214b
commit 666cbe7d47
1 changed files with 35 additions and 24 deletions
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61
src/uint.rs
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@ -58,6 +58,7 @@ macro_rules! panic_on_overflow {
}
}
}
pub trait Uint: Sized + Default + FromStr + From<u64> + FromJson + fmt::Debug + fmt::Display + PartialOrd + Ord + PartialEq + Eq + Hash {
/// Size of this type.
@ -83,11 +84,19 @@ pub trait Uint: Sized + Default + FromStr + From<u64> + FromJson + fmt::Debug +
/// Return the least number of bits needed to represent the number
fn bits(&self) -> usize;
/// Return if specific bit is set
fn bit(&self, index: usize) -> bool;
/// Return single byte
fn byte(&self, index: usize) -> u8;
/// Get this Uint as slice of bytes
fn to_bytes(&self, bytes: &mut[u8]);
/// Create `Uint(10**n)`
fn exp10(n: usize) -> Self;
/// Return eponentation `self**other`. Panic on overflow.
fn pow(self, other: Self) -> Self;
/// Return wrapped eponentation `self**other` and flag if there was an overflow
fn overflowing_pow(self, other: Self) -> (Self, bool);
}
macro_rules! construct_uint {
@ -112,14 +121,12 @@ macro_rules! construct_uint {
))
}
/// Conversion to u32
#[inline]
fn low_u32(&self) -> u32 {
let &$name(ref arr) = self;
arr[0] as u32
}
/// Conversion to u64
#[inline]
fn low_u64(&self) -> u64 {
let &$name(ref arr) = self;
@ -147,6 +154,7 @@ macro_rules! construct_uint {
}
arr[0]
}
/// Return the least number of bits needed to represent the number
#[inline]
fn bits(&self) -> usize {
@ -180,34 +188,33 @@ macro_rules! construct_uint {
}
#[inline]
fn exp10(n: usize) -> $name {
fn exp10(n: usize) -> Self {
match n {
0 => $name::from(1u64),
_ => $name::exp10(n - 1) * $name::from(10u64)
0 => Self::from(1u64),
_ => Self::exp10(n - 1) * Self::from(10u64)
}
}
#[inline]
fn zero() -> $name {
fn zero() -> Self {
From::from(0u64)
}
#[inline]
fn one() -> $name {
fn one() -> Self {
From::from(1u64)
}
/// Fast exponentation by squaring
/// https://en.wikipedia.org/wiki/Exponentiation_by_squaring
fn pow(self, expon: Self) -> Self {
if expon == Self::zero() {
return Self::one()
}
let is_even = |x : &Self| x.low_u64() & 1 == 0;
impl $name {
pub fn pow(self, expon: $name) -> $name {
if expon == $name::zero() {
return $name::one()
}
let is_even = |x : &$name| x.low_u64() & 1 == 0;
let u_one = $name::one();
let u_two = $name::from(2);
let u_one = Self::one();
let u_two = Self::from(2);
let mut y = u_one;
let mut n = expon;
let mut x = self;
@ -224,14 +231,16 @@ macro_rules! construct_uint {
x * y
}
pub fn overflowing_pow(self, expon: $name) -> ($name, bool) {
if expon == $name::zero() {
return ($name::one(), false)
/// Fast exponentation by squaring
/// https://en.wikipedia.org/wiki/Exponentiation_by_squaring
fn overflowing_pow(self, expon: Self) -> (Self, bool) {
if expon == Self::zero() {
return (Self::one(), false)
}
let is_even = |x : &$name| x.low_u64() & 1 == 0;
let is_even = |x : &Self| x.low_u64() & 1 == 0;
let u_one = $name::one();
let u_two = $name::from(2);
let u_one = Self::one();
let u_two = Self::from(2);
let mut y = u_one;
let mut n = expon;
let mut x = self;
@ -250,9 +259,11 @@ macro_rules! construct_uint {
let res = overflowing!(x.overflowing_mul(y), overflow);
(res, overflow)
}
}
impl $name {
/// Multiplication by u32
fn mul_u32(self, other: u32) -> $name {
fn mul_u32(self, other: u32) -> Self {
let $name(ref arr) = self;
let mut carry = [0u64; $n_words];
let mut ret = [0u64; $n_words];
@ -273,7 +284,7 @@ macro_rules! construct_uint {
}
/// Overflowing multiplication by u32
fn overflowing_mul_u32(self, other: u32) -> ($name, bool) {
fn overflowing_mul_u32(self, other: u32) -> (Self, bool) {
let $name(ref arr) = self;
let mut carry = [0u64; $n_words];
let mut ret = [0u64; $n_words];