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Copy path_random.RandomGen.cs
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135 lines (117 loc) · 5.04 KB
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// Copyright(c) .NET Foundation and Contributors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
using System;
namespace IronPython.Modules {
public static partial class PythonRandom {
/// <summary>
/// Generator based on the .NET Core implementation of System.Random
/// </summary>
private class RandomGen {
//
// Private Constants
//
private const int MBIG = int.MaxValue;
private const int MSEED = 161803398;
//
// Member Variables
//
private int _inext;
private int _inextp;
private int[] _seedArray = new int[56];
//
// Constructors
//
/*=========================================================================================
**Action: Initializes a new instance of the Random class, using a specified seed value
===========================================================================================*/
public RandomGen(int Seed) {
int ii = 0;
int mj, mk;
//Initialize our Seed array.
int subtraction = (Seed == int.MinValue) ? int.MaxValue : Math.Abs(Seed);
mj = MSEED - subtraction;
_seedArray[55] = mj;
mk = 1;
for (int i = 1; i < 55; i++) { //Apparently the range [1..55] is special (Knuth) and so we're wasting the 0'th position.
if ((ii += 21) >= 55) ii -= 55;
_seedArray[ii] = mk;
mk = mj - mk;
if (mk < 0) mk += MBIG;
mj = _seedArray[ii];
}
for (int k = 1; k < 5; k++) {
for (int i = 1; i < 56; i++) {
int n = i + 30;
if (n >= 55) n -= 55;
_seedArray[i] -= _seedArray[1 + n];
if (_seedArray[i] < 0) _seedArray[i] += MBIG;
}
}
_inext = 0;
_inextp = 21;
Seed = 1;
}
//
// Package Private Methods
//
private int InternalSample() {
int retVal;
int locINext = _inext;
int locINextp = _inextp;
if (++locINext >= 56) locINext = 1;
if (++locINextp >= 56) locINextp = 1;
retVal = _seedArray[locINext] - _seedArray[locINextp];
if (retVal == MBIG) retVal--;
if (retVal < 0) retVal += MBIG;
_seedArray[locINext] = retVal;
_inext = locINext;
_inextp = locINextp;
return retVal;
}
//
// Public Instance Methods
//
/*==================================NextBytes===================================
**Action: Fills the byte array with random bytes [0..0x7f]. The entire array is filled.
**Returns:Void
**Arguments: buffer -- the array to be filled.
**Exceptions: None
==============================================================================*/
public void NextBytes(byte[] buffer) {
if (buffer == null) throw new ArgumentNullException(nameof(buffer));
for (int i = 0; i < buffer.Length; i++) {
buffer[i] = (byte)InternalSample();
}
}
internal object[] GetState() {
var state = new object[58];
Array.Copy(_seedArray, state, _seedArray.Length);
state[56] = _inext;
state[57] = _inextp;
return state;
}
internal void SetState(int[] state) {
Array.Copy(state, _seedArray, _seedArray.Length);
_inext = state[56];
_inextp = state[57];
}
}
}
}