Nuclex.Support/Source/IntegerHelper.cs

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#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2013 Nuclex Development Labs
This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.
You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion
using System;
using System.Collections.Generic;
namespace Nuclex.Support {
/// <summary>Helper methods for working with integer types</summary>
public static class IntegerHelper {
/// <summary>Returns the next highest power of 2 from the specified value</summary>
/// <param name="value">Value of which to return the next highest power of 2</param>
/// <returns>The next highest power of 2 to the value</returns>
public static long NextPowerOf2(this long value) {
return (long)NextPowerOf2((ulong)value);
}
/// <summary>Returns the next highest power of 2 from the specified value</summary>
/// <param name="value">Value of which to return the next highest power of 2</param>
/// <returns>The next highest power of 2 to the value</returns>
public static ulong NextPowerOf2(this ulong value) {
if (value == 0)
return 1;
--value;
value |= value >> 1;
value |= value >> 2;
value |= value >> 4;
value |= value >> 8;
value |= value >> 16;
value |= value >> 32;
++value;
return value;
}
/// <summary>Returns the next highest power of 2 from the specified value</summary>
/// <param name="value">Value of which to return the next highest power of 2</param>
/// <returns>The next highest power of 2 to the value</returns>
public static int NextPowerOf2(this int value) {
return (int)NextPowerOf2((uint)value);
}
/// <summary>Returns the next highest power of 2 from the specified value</summary>
/// <param name="value">Value of which to return the next highest power of 2</param>
/// <returns>The next highest power of 2 to the value</returns>
public static uint NextPowerOf2(this uint value) {
if (value == 0)
return 1;
--value;
value |= value >> 1;
value |= value >> 2;
value |= value >> 4;
value |= value >> 8;
value |= value >> 16;
++value;
return value;
}
/// <summary>Returns the number of bits set in an </summary>
/// <param name="value">Value whose bits will be counted</param>
/// <returns>The number of bits set in the integer</returns>
public static int CountBits(this int value) {
return CountBits((uint)value);
}
/// <summary>Returns the number of bits set in an unsigned integer</summary>
/// <param name="value">Value whose bits will be counted</param>
/// <returns>The number of bits set in the unsigned integer</returns>
/// <remarks>
/// Based on a trick revealed here:
/// http://stackoverflow.com/questions/109023
/// </remarks>
public static int CountBits(this uint value) {
value = value - ((value >> 1) & 0x55555555);
value = (value & 0x33333333) + ((value >> 2) & 0x33333333);
return (int)unchecked(
((value + (value >> 4) & 0xF0F0F0F) * 0x1010101) >> 24
);
}
/// <summary>Returns the number of bits set in a long integer</summary>
/// <param name="value">Value whose bits will be counted</param>
/// <returns>The number of bits set in the long integer</returns>
public static int CountBits(this long value) {
return CountBits((ulong)value);
}
/// <summary>Returns the number of bits set in an unsigned long integer</summary>
/// <param name="value">Value whose bits will be counted</param>
/// <returns>The number of bits set in the unsigned long integer</returns>
/// <remarks>
/// Based on a trick revealed here:
/// http://stackoverflow.com/questions/2709430
/// </remarks>
public static int CountBits(this ulong value) {
value = value - ((value >> 1) & 0x5555555555555555UL);
value = (value & 0x3333333333333333UL) + ((value >> 2) & 0x3333333333333333UL);
return (int)unchecked(
(((value + (value >> 4)) & 0xF0F0F0F0F0F0F0FUL) * 0x101010101010101UL) >> 56
);
}
}
} // namespace Nuclex.Support