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/*
* PCG Random Number Generation for Rust
*
* Copyright 2015 John Brooks <robojeb@robojeb.xyz>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
/// The types of numaric options that PCG needs to operate.
/// Some day this will be replaced with Num-traits when they support
/// wrapping opts for everything, and when extprim supports those traits as
/// well.
pub trait PcgOps {
fn wrap_mul(&self, rhs: Self) -> Self;
fn wrap_add(&self, rhs: Self) -> Self;
}
/// Convert a value to a usize don't care about overflow etc
pub trait AsUsize {
fn as_usize(&self) -> usize;
}
/// A trait that determines how many bits are in a type.
pub trait BitSize {
const BITS: usize;
}
/// Allows a type to become a type of a smaller value.
pub trait AsSmaller<T> {
fn shrink(self) -> T;
}
//Implementations of the traits for basic types
macro_rules! basic_ops {
( $( $t:ty, $bits:expr);*) => {
$(impl BitSize for $t {
const BITS: usize = $bits;
}
impl AsUsize for $t {
#[inline]
fn as_usize(&self) -> usize {
*self as usize
}
}
impl PcgOps for $t {
#[inline]
fn wrap_mul(&self, rhs : $t) -> $t {
self.wrapping_mul(rhs)
}
#[inline]
fn wrap_add(&self, rhs : $t) -> $t {
self.wrapping_add(rhs)
}
}
)*
}
}
basic_ops!(
u8, 8;
u16, 16;
u32, 32;
u64, 64;
u128, 128
);
macro_rules! smaller {
( $( $t:ty, $other:ty);*) => {
$(
impl AsSmaller<$other> for $t {
#[inline]
fn shrink(self) -> $other {
self as $other
}
}
)*
}
}
smaller!(
u128, u64;
u128, u32;
u128, u16;
u128, u8;
u64, u32;
u64, u16;
u64, u8;
u32, u16;
u32, u8;
u16, u8
);
// impl PcgOps for u128 {
// #[inline]
// fn wrap_mul(&self, rhs : u128) -> u128 {
// self.wrapping_mul(rhs)
// }
// #[inline]
// fn wrap_add(&self, rhs : u128) -> u128 {
// self.wrapping_add(rhs)
// }
// }