basex.php

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<?php
/* vim: set expandtab tabstop=4 shiftwidth=4: */
// +----------------------------------------------------------------------+
// | PHP Version 4                                                        |
// +----------------------------------------------------------------------+
// | Copyright (c) 1997-2003 The PHP Group                                |
// +----------------------------------------------------------------------+
// | This source file is subject to version 2.0 of the PHP license,       |
// | that is bundled with this package in the file LICENSE, and is        |
// | available at through the world-wide-web at                           |
// | http://www.php.net/license/2_02.txt.                                 |
// | If you did not receive a copy of the PHP license and are unable to   |
// | obtain it through the world-wide-web, please send a note to          |
// | [e-mail] so we can mail you a copy immediately.               |
// +----------------------------------------------------------------------+
// | Authors: Dave Mertens <[e-mail]>                        |
// +----------------------------------------------------------------------+
//
// $Id: Basex.php,v 1.6 2003/06/04 14:48:44 et Exp $

require_once "PEAR.php";

if (!defined('MATH_BASEX_MATHEXTENSION')) {
    if (PEAR::loadExtension('bcmath')) {
        define('MATH_BASEX_MATHEXTENSION', 'bcmath');
    } elseif (PEAR::loadExtension('gmp')) {
        define('MATH_BASEX_MATHEXTENSION', 'gmp');
    } else {
        define('MATH_BASEX_MATHEXTENSION', 'none');
    }
}

/**
* base X coding class
*
* I noticed that value of an int is different on most systems. 
* On my system (linux 2.4.18 with glibc 2.2.5) i can use 8-byte integers 
* (also called int64 or int8)
* On my laptop (Windows 2000) i only could use numbers up to 4-byte (32 bit) 
* integers.
* So you might want to test this first!
*
* Note that you can without much effort also use the bcmath extentions to 
* increase the length of your numbers.
*
* @author Dave Mertens <[e-mail]>
* @version 0.3
* @access public
* @package Math_Basex
* @category Math
*/
class Math_Basex
{
    /**
    * @var character base set
    * @access private;
    */
    var $_baseChars;

    /**
    * @var base length (for binair 2, dec 10, hex 16, yours ??)
    * @access private;
    */
    var $_length;
    
    /**
    * Constructor for class
    *
    * @param tokens string Character base set (Each character is only allowed 
    *                                          once!)
    * @return void
    */
    function Math_Basex($tokens = "")
    {
        //set initial length
        $this->_length = 0;
        
        //if we did get already a character set, set it..
        if (!empty($tokens)) {
            $this->setBase($tokens);
        }
    }
            
    
    /**
    * Change the character base set. Behaves the same way the constructor does.
    *
    * @param tokens string Character base set (Each character is only allowed 
    *                                          once!)
    * @return void
    * @access public
    */
    function setBase($tokens)
    {
        if (!$this->_checkBase($tokens)) {
            return PEAR::raiseError("Each character is only allowed once");
        }
        $this->_baseChars = $tokens;
        $this->_length = strlen($tokens);
        return true;
    }
    
    /**
    * toBase translates a decimal (base 10) number into your base 'code'
    *
    * @param number (int64 or double without floats, both are 8-byte number 
    *         types). This allows you to use numbers up to 18446744073709551616.
    * @return string encoded 'code' of yout decimal number
    */
    function toBase($number)
    {
        if (!is_numeric($number)) {
            return PEAR::raiseError("You must supply a decimal number");
        }
            
        if ($this->_length == 0) {
            return PEAR::raiseError("Character base isn't defined yet..");
        }
        if (is_float($number)) {
            $number = ltrim(sprintf('%22.0f',$number));
        }

        $code = "";
        do {
            $this->_splitnumber($number, $full, $mod);
            $code = $this->_getToken($mod) . $code;
            $number = $full;
        } while ($number > 0);
        
        return $code;
        
    }
    
    /**
    * toDecimal decodes the baseX 'code' back to a decimal number
    *
    * @param string code to decode
    * @return int64 decimal (base 10) number
    */
    function todecimal($code)
    {
        $length = strlen($code);
        $total = 0;
        
        if (strspn($code, $this->_baseChars) != $length) {
            return PEAR::raiseError("Your Base X code contains invalid"
                                   ." characters");
        }

        for ($i=0; $i < $length; $i++) {
            $sum = $this->_getNumber($code[$length - $i - 1]) * 
                                     $this->_pow($this->_length, $i);
            $total = $this->_add($total,$sum);
        }
        
        return $total;
    }
    
    /**
    * Returns the base scale. Note that this is onyl the count of the 
    * characters used for the encoding and decoding.
    * Please do not use base_convert with this class, because it might result 
    * in rare results
    *
    * @access public
    * @return integer
    */
    function getBase()
    {
        return $this->_length;
    }
    
    /**
    * Validates whether each character is unique
    *
    * @param string tokens Character base set
    * @access private
    * @return boolean true if all characters are unique
    */
    function _checkBase($tokens)
    {
        $length = strlen($tokens);
        for ($i=0; $i < $length; $i++) {
            if (substr_count($tokens, $tokens[$i]) > 1)
                return false;    //character is specified more than one time!
        }
        
        //if we come here, all characters are unique
        return true;
    }
    
    /**
    * Helper function for encoding function. 
    *
    * @access private;
    * @param number integer number to spilt for base conversion
    * @param full integer non-float, unrounded number (will be passed as 
    *                     reference)
    * @param modules float floating number between 0 and 1 
    *                     (will be passed as reference)
    *
    * @return void
    */
    function _splitNumber($number, &$full, &$modules)
    {
        $full = $this->_div($number, $this->_length);
        $modules = $this->_mod($number, $this->_length);
    }

    /**
    * Helper function; Returns character at position x
    *
    * @param oneDigit integer number between 0 and basex->getBase()
    * @return character from base character set
    * @access private;
    */
    function _getToken($oneDigit)
    {
        return substr($this->_baseChars, $oneDigit, 1);
    }
    
    /**
    * Helper function; Returns position of character X
    *
    * @param oneDigit string Character in base character set
    * @return integer number between 0 and basex->getBase()
    * @access private;
    */
    function _getNumber($oneDigit)
    {
        return strpos($this->_baseChars, $oneDigit);
    }    

    /**
    * Add two numbers, utilize Math extensions
    *
    * @param mixed a First operand
    * @param mixed b Second operand
    * @return mixed
    * @access private
    */
    function _add($a, $b)
    {
        switch (MATH_BASEX_MATHEXTENSION) {
        case 'bcmath':
            return bcadd($a, $b);
        case 'gmp':
            return gmp_strval(gmp_add($a, $b));
        case 'none':
            return $a + $b;
        }
    }

    /**
    * Multiply two numbers, utilize Math extensions
    *
    * @param mixed a First operand
    * @param mixed b Second operand
    * @return mixed
    * @access private
    */
    function _mul($a, $b)
    {
        switch (MATH_BASEX_MATHEXTENSION) {
        case 'bcmath':
            return bcmul($a, $b);
        case 'gmp':
            return gmp_strval(gmp_mul($a, $b));
        case 'none':
            return $a * $b;
        }

    }

    /**
    * Return the modulo of two numbers, utilize Math extensions
    *
    * @param mixed a First operand
    * @param mixed b Second operand
    * @return mixed
    * @access private
    */
    function _mod($a, $b)
    {
        switch (MATH_BASEX_MATHEXTENSION) {
        case 'bcmath':
            return bcmod($a, $b);
        case 'gmp':
            return gmp_strval(gmp_mod($a, $b));
        case 'none':
            return $a % $b;
        }
    }

    /**
    * Divide two integers, utilize Math extensions
    *
    * @param mixed a First operand
    * @param mixed b Second operand
    * @return mixed
    * @access private
    */
    function _div($a, $b)
    {
        switch (MATH_BASEX_MATHEXTENSION) {
        case 'bcmath':
            return bcdiv($a, $b);
        case 'gmp':
            return gmp_strval(gmp_div($a, $b));
        case 'none':
            return floor($a / $b);
        }
    }

    /**
    * Raise one number to the power of the other, utilize Math extensions
    *
    * @param mixed a First operand
    * @param mixed b Second operand
    * @return mixed
    * @access private
    */
    function _pow($a, $b)
    {
        switch (MATH_BASEX_MATHEXTENSION) {
        case 'bcmath':
            return bcpow($a, $b);
        case 'gmp':
            return gmp_strval(gmp_pow($a, $b));
        case 'none':
            return pow($a,$b);
        }
    }

    /**
    * Returns a common set of digits (0-9A-Za-z), length is given as parameter
    *
    * @param int length Optional How many characters to return, defaults to 62.
    * @return string
    * @access public
    */
    function stdBase($n = 62) 
    {
        return substr("0123456789"
                     ."ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                     ."abcdefghijklmnopqrstuvwxyz", 0, $n);
    }

    /**
    * Converts a number from one base into another. May be called statically.
    * 
    * @param mixed number The number to convert
    * @param int from_base The base to convert from
    * @param int to_base The base to convert to
    * @param string from_cs Optional character set of the number that is
    *                                converted
    * @param string to_cs Optional character set of the target number
    * @return string
    * @access public
    */
    function baseConvert($number, $from_base, $to_base, 
                          $from_cs = null, $to_cs = null)
    {
        if (isset($this)) {
            $obj = &$this;
        } else {
            $obj = &Math_Basex::instance();
        }
        if (!isset($from_cs)) {
            $from_cs = $obj->stdBase();
        }
        if (!isset($to_cs)) {
            $to_cs = $obj->stdBase();
        }
        if (strlen($from_cs) < $from_base) {
            return PEAR::raiseError('Character set isn\'t long enough for the'
                                   .'given base.');
        }
        if (strlen($to_cs) < $to_base) {
            return PEAR::raiseError('Character set isn\'t long enough for the'
                                   .'given base.');
        }
        $from_cs = substr($from_cs, 0, $from_base);
        $to_cs   = substr($to_cs,   0, $to_base);
        if ($tmp = $obj->setBase($from_cs) !== true) {
            return $tmp;
        }
        $number = $obj->toDecimal($number);
        if (PEAR::isError($number)) {
            return $number;
        }
        if ($tmp = $obj->setBase($to_cs) !== true) {
            return $tmp;
        }
        $number = $obj->toBase($number);
        return $number;
    }

    /**
    * Singleton method, call statically
    *
    * @return object
    * @access public
    */
    function &instance()
    {
        static $ins = null;
        if (is_null($ins)) {
            $ins = new Math_Basex;
        }
        return $ins;
    }
}

?>