Decimal to/from BASE 62. 10進数⇔62進数コンバータ for PHP decodeが遅そう

base62.php

<?php

/* base62.php
 * by Keiya Chinen. Licensed under Creative Commons BY 3.0
 * ( http://creativecommons.org/licenses/by/3.0/deed.en )
 */

// test script
//test();

//example
example(12345);

function example($n) {
  $b62 = Base62::b62_encode($n);
	$dec = Base62::b62_decode($b62);
	echo "$n --> $b62 --> $dec\n";
}

function test() {
	for ($i=10000000;$i<1000000000;++$i) {
		$b62 = Base62::b62_encode($i);
		$dec = Base62::b62_decode($b62);
		if ($i === $dec) {
		}
		else {
			echo 'x';
		}
	}
}

class Base62 {
	const RADIX = 62;

	static $decmap = array(
		'0','1','2','3','4','5','6','7','8','9',
		'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
		'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'
	);

	public function b62_encode($num) {
		$result = '';
		while ($num > 0) {
			$result = self::$decmap[$num % self::RADIX] . $result;
			$num = intval($num / self::RADIX);
		}
		return $result;
	}
	
	public function b62_decode($str) {
		$length = strlen($str);
		$result = 0;
		for ($i = 0; $i < $length; ++$i) {
			$decval = array_search($str[$i],self::$decmap);
			$result += $decval * pow(self::RADIX,$length-$i-1);
		}
		return $result;
	}

}