rik/plibreader
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Add support for bit twiddling

Browse Source 
git-svn-id: http://php-reader.googlecode.com/svn/trunk@110 51a70ab9-7547-0410-9469-37e369ee0574
This commit is contained in:
svollbehr
2008-09-05 17:10:51 +00:00
parent 5ab1bb40f6
commit 26ca06e619
1 changed files with 235 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

235
src/Twiddling.php Normal file
View File

@@ -0,0 +1,235 @@
<?php
/**
* PHP Reader Library
*
* Copyright (c) 2008 The PHP Reader Project Workgroup. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the project workgroup nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* @package php-reader
* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
* @license http://code.google.com/p/php-reader/wiki/License New BSD License
* @version $Id$
*/
/**
* A utility class to perform bit twiddling on integers.
*
* @package php-reader
* @author Ryan Butterfield <buttza@gmail.com>
* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
* @license http://code.google.com/p/php-reader/wiki/License New BSD License
* @version $Rev$
* @static
*/
final class Twiddling
{
/**
* Default private constructor for a static class.
*/
private function __construct() {}
/**
* Sets a bit at a given position in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $position The position of the bit to set.
* @param boolean $on Whether to enable or clear the bit.
* @return integer
*/
public static function setBit($integer, $position, $on)
{
return $on ? self::enableBit($integer, $position) :
self::clearBit($integer, $position);
}
/**
* Enables a bit at a given position in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $position The position of the bit to enable.
* @return integer
*/
public static function enableBit($integer, $position)
{
return $integer | (1 << $position);
}
/**
* Clears a bit at a given position in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $position The position of the bit to clear.
* @return integer
*/
public static function clearBit($integer, $position)
{
return $integer & ~(1 << $position);
}
/**
* Toggles a bit at a given position in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $position The position of the bit to toggle.
* @return integer
*/
public static function toggleBit($integer, $position)
{
return $integer ^ (1 << $position);
}
/**
* Tests a bit at a given position in an integer.
*
* @param integer $integer The value to test.
* @param integer $position The position of the bit to test.
* @return boolean
*/
public static function testBit($integer, $position)
{
return ($integer & (1 << $position)) != 0;
}
/**
* Sets a given set of bits in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $bits The bits to set.
* @param boolean $on Whether to enable or clear the bits.
* @return integer
*/
public static function setBits($integer, $bits, $on)
{
return $on ? self::enableBits($integer, $bits) :
self::clearBits($integer, $bits);
}
/**
* Enables a given set of bits in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $bits The bits to enable.
* @return integer
*/
public static function enableBits($integer, $bits)
{
return $integer | $bits;
}
/**
* Clears a given set of bits in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $bits The bits to clear.
* @return integer
*/
public static function clearBits($integer, $bits)
{
return $integer & ~$bits;
}
/**
* Toggles a given set of bits in an integer.
*
* @param integer $integer The value to manipulate.
* @param integer $bits The bits to toggle.
* @return integer
*/
public static function toggleBits($integer, $bits)
{
return $integer ^ $bits;
}
/**
* Tests a given set of bits in an integer
* returning whether all bits are set.
*
* @param integer $integer The value to test.
* @param integer $bits The bits to test.
* @return boolean
*/
public static function testAllBits($integer, $bits)
{
return ($integer & $bits) == $bits;
}
/**
* Tests a given set of bits in an integer
* returning whether any bits are set.
*
* @param integer $integer The value to test.
* @param integer $bits The bits to test.
* @return boolean
*/
public static function testAnyBits($integer, $bits)
{
return ($integer & $bits) != 0;
}
/**
* Stores a value in a given range in an integer.
*
* @param integer $integer The value to store into.
* @param integer $start The position to store from. Must be <= $end.
* @param integer $end The position to store to. Must be >= $start.
* @param integer $value The value to store.
* @return integer
*/
public static function setValue($integer, $start, $end, $value)
{
return self::clearBits($integer, self::getMask($start, $end) << $start) |
($value << $start);
}
/**
* Retrieves a value from a given range in an integer, inclusive.
*
* @param integer $integer The value to read from.
* @param integer $start The position to read from. Must be <= $end.
* @param integer $end The position to read to. Must be >= $start.
* @return integer
*/
public static function getValue($integer, $start, $end)
{
return ($integer & self::getMask($start, $end)) >> $start;
}
/**
* Returns an integer with all bits set from start to end.
*
* @param integer $start The position to start setting bits from. Must
* be <= $end.
* @param integer $end The position to stop setting bits. Must be >= $start.
* @return integer
*/
public static function getMask($start, $end)
{
$mask = 0;
for (; $start <= $end; $start++)
$mask |= 1 << $start;
return $mask;
}
}