<?php

const B16_STR = '0123456789abcdef';
const B36_STR = '0123456789abcdefghijklmnopqrstuvwxyz';
const B64_STR = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-';

function gcd($a,$b){
	return ($a%$b)?gcd($b,$a%$b):$b;
}
function convert($str, $from, $to){
	$len_from = strlen($from);
	$len_to = strlen($to);
	if(!preg_match('/^['.$from.']+$/'.(preg_match('/^([^[:upper:]]*|[^[:lower:]]*)(?1)*(?!\1)$/', $from)?'':'i'),$str)
				|| $len_from<=0 || $len_to<=0){
		throw new Exception();
	}
	$buf = [];
	$offset = 0;
	$l = strlen($str);
	$c = 0;
	$bits_from;$bits_to;
	$segs_from;$segs_to;
	{
		$log2 = log(2);
		$bits_from = log($len_from)/$log2;
		$bits_to   = log($len_to)/$log2;
		$lcm = $bits_from*$bits_to/gcd($bits_from,$bits_to);
		$segs_from = $lcm / $bits_from;
		$segs_to   = $lcm / $bits_to;
	}
	while($offset<$l){
		for($j=0;$j<$segs_from;$j++){
			$c |= strpos($from, $str[($offset<$l)?$offset++:0])<<($bits_from*$j);
		}
		for($i=0;$i<$segs_to;$i++){
			array_push($buf, $to[($c>>($i*$bits_to))&($len_to-1)]);
		}
		$c = 0;
	}
	return implode($buf);
}
function hex64($str){
	return convert($str, B16_STR, B64_STR);
}
function hex64r($str){
	return convert($str, B64_STR, B16_STR);
}
function convertTest($TEST_COUNT = 1000000){
	$failed = 0;
	for($i=0;$i<$TEST_COUNT;$i++){
		$h = hash('whirlpool', 'a'.rand());
		$t = substr(hex64r(hex64($h)),0,strlen($h));
		if(!$h===$t){
			echo $h,"\n<br>",$t,"\n<br>\n<br>";
			$failed++;
		}
	}
	echo 'Passed ',$TEST_COUNT-$failed,' out of ',$TEST_COUNT;
}

convertTest(1000);
?>