Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
branch: master
Fetching contributors…

Cannot retrieve contributors at this time

79 lines (66 sloc) 2.676 kb
<?php
/**
* A pure PHP implementation of NewBase60. A base 60 numbering system designed for
* use with URL shortening. Limited/overlapping character set to avoid confusion
* between similar characters, eg o/0, i/l, etc.
*
* Q: Why not use PHP base_convert()?
* A: Because it only goes up to base 36, and doesn't support the NewBase60
*
* @see http://tantek.pbworks.com/w/page/19402946/NewBase60
* @see http://en.wikipedia.org/wiki/sexagesimal
*
* @author david@dsingleton.co.uk
*/
class NewBase60
{
protected static $characterSet = '0123456789ABCDEFGHJKLMNPQRSTUVWXYZ_abcdefghijkmnopqrstuvwxyz';
/**
* Convert a sexagesimal number to a decimal number
* @param string sexagesimal number to convert
* @return integer Decimal representation of sexagesimal number
*/
public static function toDecimal($sexNum)
{
// Return falsy and 0 values as is
if (!$sexNum) {
return $sexNum === '0' ? 0 : $sexNum;
}
$decNum = 0;
foreach(str_split($sexNum) as $chr) {
$ord = ord($chr);
if ($ord>=48 && $ord<=57) { $ord -= 48; } // 0 - 9
elseif ($ord>=65 && $ord<=72) { $ord -= 55; } // A - H
elseif ($ord==73 || $ord==108) { $ord = 1; } // Error correct typo: capital I, lowercase l to 1
elseif ($ord>=74 && $ord<=78) { $ord -= 56; } // J - N
elseif ($ord==79) { $ord = 0; } // Error correct typo: capital O to 0
elseif ($ord>=80 && $ord<=90) { $ord -= 57; } // P - Z
elseif ($ord==95) { $ord = 34; } // underscore
elseif ($ord>=97 && $ord<=107) { $ord -= 62; } // a - k
elseif ($ord>=109 && $ord<=122) { $ord -= 63; } // m - z
else { $ord = 0; } // treat all other noise as 0
$decNum = 60 *$decNum + $ord;
}
return $decNum;
}
/**
* Convert a decimal number to a sexagesimal number
* @param integer Decimal number to convert
* @return string sexagesimal representation of decimal
*/
public static function fromDecimal($decNum)
{
$decNum = (int) $decNum;
if (!$decNum) {
return $decNum === 0 ? '0' : $sexNum;
}
$aSexCharset = self::$characterSet;
$result = '';
while ($decNum > 0) {
$decRemainder = $decNum % 60;
$decNum = ($decNum - $decRemainder) / 60;
$result = $aSexCharset[$decRemainder] . $result;
}
return $result;
}
}
Jump to Line
Something went wrong with that request. Please try again.