Created
September 26, 2019 13:43
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base85.php
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| <?PHP | |
| #error_reporting(E_ALL); | |
| // Examples: | |
| // $str = base85::encode("Hello world!"); | |
| // $str = base85::decode(":e4D*;K$&\Er"); | |
| class base85 | |
| { | |
| public static function decode($str) { | |
| $str = preg_replace("/ \t\r\n\f/","",$str); | |
| $str = preg_replace("/z/","!!!!!",$str); | |
| $str = preg_replace("/y/","+<VdL/",$str); | |
| // Pad the end of the string so it's a multiple of 5 | |
| $padding = 5 - (strlen($str) % 5); | |
| if (strlen($str) % 5 === 0) { | |
| $padding = 0; | |
| } | |
| $str .= str_repeat('u',$padding); | |
| $num = 0; | |
| $ret = ''; | |
| // Foreach 5 chars, convert it to an integer | |
| while ($chunk = substr($str, $num * 5, 5)) { | |
| $tmp = 0; | |
| foreach (unpack('C*',$chunk) as $item) { | |
| $tmp *= 85; | |
| $tmp += $item - 33; | |
| } | |
| // Convert the integer in to a string | |
| $ret .= pack('N', $tmp); | |
| $num++; | |
| } | |
| // Remove any padding we had to add | |
| $ret = substr($ret,0,strlen($ret) - $padding); | |
| return $ret; | |
| } | |
| public static function encode($str) { | |
| $ret = ''; | |
| $debug = 0; | |
| $padding = 4 - (strlen($str) % 4); | |
| if (strlen($str) % 4 === 0) { | |
| $padding = 0; | |
| } | |
| if ($debug) { | |
| printf("Length: %d = Padding: %s<br /><br />\n",strlen($str),$padding); | |
| } | |
| // If we don't have a four byte chunk, append \0s | |
| $str .= str_repeat("\0", $padding); | |
| foreach (unpack('N*',$str) as $chunk) { | |
| // If there is an all zero chunk, it has a shortcut of 'z' | |
| if ($chunk == "\0") { | |
| $ret .= "z"; | |
| continue; | |
| } | |
| // Four spaces has a shortcut of 'y' | |
| if ($chunk == 538976288) { | |
| $ret .= "y"; | |
| continue; | |
| } | |
| if ($debug) { | |
| var_dump($chunk); print "<br />\n"; | |
| } | |
| // Convert the integer into 5 "quintet" chunks | |
| for ($a = 0; $a < 5; $a++) { | |
| $b = intval($chunk / (pow(85,4 - $a))); | |
| $ret .= chr($b + 33); | |
| if ($debug) { | |
| printf("%03d = %s <br />\n",$b,chr($b+33)); | |
| } | |
| $chunk -= $b * pow(85,4 - $a); | |
| } | |
| } | |
| // If we added some null bytes, we remove them from the final string | |
| if ($padding) { | |
| $ret = preg_replace("/z$/",'!!!!!',$ret); | |
| $ret = substr($ret,0,strlen($ret) - $padding); | |
| } | |
| return $ret; | |
| } | |
| } // End of base85 class |
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