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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 trait helps define the size of the extension of the PCG generator
/// this allows the size of the extension to effectively be part of the
/// type of the extended generator.
///
/// These extensions have to be a power of two based on the way the generator
/// utilizes its extension.
/// This could be made much better with associated constants and constant
/// functions, or by type level numbers.
///
/// Already provided are:
/// * Ext2
/// * Ext4
/// * Ext8
/// * Ext16
/// * Ext32
/// * Ext64
/// * Ext128
/// * Ext256
/// * Ext512
/// * Ext1024
/// Bigger extensions can be produced and dropped as long as they are powers of
/// 2
pub trait ExtSize {
const EXT_SIZE: usize;
const EXT_BITS: u32;
}
macro_rules! make_ext_size {
($($i:ident, $size:expr, $bits:expr);*) => {
$(pub struct $i;
impl ExtSize for $i {
const EXT_SIZE: usize = $size;
const EXT_BITS: u32 = $bits;
})*
}
}
make_ext_size!(
Ext2, 2, 1;
Ext4, 4, 2;
Ext8, 8, 3;
Ext16, 16, 4;
Ext32, 32, 5;
Ext64, 64, 6;
Ext128, 128, 7;
Ext256, 256, 8;
Ext512, 512, 9;
Ext1024, 1024, 10
);