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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.
*
* This work is derived from the implementation PCG RNG for C++ by
* Melissa O'Neill.
*
* For additional information about the PCG random number generation scheme,
* including its license and other licensing options, visit
*
* http://www.pcg-random.org
*/
/// This trait provides the multiplier for the internal LCG of the PCG generator
/// Implementing this trait for a struct will allow providing your own
/// multiplier for the PCG.
pub trait Multiplier<Itype> {
fn multiplier() -> Itype;
}
/// Provides a default "good" multiplier based on the multiplier provided
/// in the C++ implementation of PCG
#[cfg_attr(feature = "serde1", derive(Serialize, Deserialize))]
pub struct DefaultMultiplier;
macro_rules! make_default_mul {
( $( $t:ty => $e:expr);* ) => {
$(
impl Multiplier<$t> for DefaultMultiplier {
#[inline]
fn multiplier() -> $t {
$e
}
})*
}
}
make_default_mul!(
u8 => 141u8;
u16 => 12829u16;
u32 => 747_796_405u32;
u64 => 6_364_136_223_846_793_005u64;
u128 => 47_026_247_687_942_121_848_144_207_491_837_523_525u128 //u128::from_parts(2549297995355413924, 4865540595714422341)
);
/// Provides a default "good" multiplier based on the multiplier provided
/// in the C++ implementation of PCG for the MCG variant of the PCG generator.
#[cfg_attr(feature = "serde1", derive(Serialize, Deserialize))]
pub struct McgMultiplier;
macro_rules! make_mcg_mul {
( $( $t:ty => $e:expr);* ) => {
$(
impl Multiplier<$t> for McgMultiplier {
#[inline]
fn multiplier() -> $t {
$e
}
})*
}
}
make_mcg_mul!(
u8 => 217u8;
u16 => 62169u16;
u32 => 277_803_737u32;
u64 => 12_605_985_483_714_917_081u64;
u128 => 327_738_287_884_841_127_335_028_083_622_016_905_945u128//u128::from_parts(17766728186571221404,12605985483714917081)
);