Online PHP editor | output for 5A0pD

<?php function string_shift_left($input, $inputlen, $bits, &$output = null) { $skip = (int) ($bits / 8); $copylen = (int) ($inputlen - $skip); $offset = ($bits % 8) & 0xff; $mask = ~(0xff >> (8 - $offset)) & 0xff; $output = str_pad('', $inputlen + 1, "\x00"); echo "$skip $copylen $offset $mask\n"; if ($offset == 0) { /* Shifting multiples of 8 allows us to simply copy the relevant bytes */ for ($i = 0; $i < $copylen; $i++) { $output[$i] = $input[$i + $skip]; } return; } for ($i = 0; $i < $copylen; $i++) { $left = (ord($input[$i + $skip]) << $offset); $right = (ord($input[$i + $skip + 1]) & $mask) >> $offset; printf("%02x ", $left | $right); $output[$i] = chr($left | $right); } } //0b000100010001000100000000; $input = "abc\x00"; $bits = 2; string_shift_left($input, strlen($input) - 1, $bits, $output); for ($i = 0; $i < strlen($output); $i++) { printf("\n%02x: %08b", ord($output[$i]), ord($output[$i])); }