Online PHP editor | rfc for MtBjQ

<?php function base62encode($data) { $outstring = ''; $l = strlen($data); for ($i = 0; $i < $l; $i += 8) { $chunk = substr($data, $i, 8); $outlen = ceil((strlen($chunk) * 8)/6); //8bit/char in, 6bits/char out, round up $x = bin2hex($chunk); //gmp won't convert from binary, so go via hex $w = gmp_strval(gmp_init(ltrim($x, '0'), 16), 62); //gmp doesn't like leading 0s $pad = str_pad($w, $outlen, '0', STR_PAD_LEFT); $outstring .= $pad; } return $outstring; } /** * Decode base-62 encoded text into binary * Note that because base-62 encodes slightly less than 6 bits per character (actually 5.95419631038688), there is some wastage * In order to make this practical, we chunk in groups of up to 11 input chars, which give up to 8 output chars * with a wastage of up to 4 bits per chunk, so while the output is not quite as space efficient as a * true multiprecision conversion, it's orders of magnitude faster * Note that the input of this function is not compatible with that of a multiprecision conversion, but it's a practical encoding implementation * The encoding overhead tends towards 37.5% with this chunk size; bigger chunk sizes can be slightly more space efficient, but may be slower * Base-64 doesn't suffer this problem because it fits into exactly 6 bits, so it generates the same results as a multiprecision conversion * Requires PHP 5.3.2 and gmp 4.2.0 * @param string $data Base-62 encoded text (not chunked or split) * @return string Decoded binary data */ function base62decode($data) { $outstring = ''; $l = strlen($data); for ($i = 0; $i < $l; $i += 11) { $chunk = substr($data, $i, 11); $outlen = floor((strlen($chunk) * 6)/8); //6bit/char in, 8bits/char out, round down $y = gmp_strval(gmp_init(ltrim($chunk, '0'), 62), 16); //gmp doesn't like leading 0s $pad = str_pad($y, $outlen * 2, '0', STR_PAD_LEFT); //double output length as as we're going via hex (4bits/char) $outstring .= pack('H*', $pad); //same as hex2bin } return $outstring; } $data = "?1,2,3,45,4536,1234567"; $encode = base62encode($data); echo 'Encode: '.$encode; echo ' - '.base62decode($encode);

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