Online PHP editor | output for 6VbIo

<?php function pack_encode($val) { $str = ''; while ($val > 0) { $str .= chr($val & 0xFF); $val = $val >> 8; } // "/" json-encodes poorly and "=" is padding return str_replace( array('/', '='), array('_', ''), base64_encode($str) ); } function pack_decode($bin) { $str = base64_decode(str_replace('_', '/', $bin)); $val = 0; for ($i=0; $i<strlen($str); $i++) { $val |= (ord($str[$i]) << ($i * 8)); } return $val; } for ($i=0; $i<32; $i++) { $val = 1<<$i; $enc = pack_encode($val); $dec = pack_decode($enc); echo "$val => $enc => $dec\n"; } for ($i=1; $i < (1<<32); $i = $($i<<1)) { $enc = pack_encode($val); $dec = pack_decode($val); echo "$enc $dec $val\n"; }