<?php

# This program is in the public domain within the United States. Additionally,
# we waive copyright and related rights in the work worldwide through the CC0
# 1.0 Universal public domain dedication, which can be found at
# http://creativecommons.org/publicdomain/zero/1.0/


# This file contains code to work with "raw" binary numbers in big-endian format


# return a 4 byte string that represent the passed integer as a big-endian binary number
function to_raw_int($int) {
	return chr($int >> 24) . chr(($int >> 16) & 0xff) . chr(($int >> 8) & 0xff) . chr($int & 0xff);
}

# return a php number from the string you pass in. The first 4 bytes of the
# string are read in as a binary value in big-endian format.
function from_raw_int($quad) {
	return (ord(substr($quad, 0, 1)) << 24) + (ord(substr($quad, 1, 1)) << 16) + (ord(substr($quad, 2, 1)) << 8) + ord(substr($quad, 3, 1));
}

function int_at($string, $index) {
	return from_raw_int(substr($string, $index * 4, 4));
}

# remove the first 4 bytes of the string, and return them as an int
function pop_int(&$string) {
	$int = from_raw_int(substr($string, 0, 4));
	$string = substr($string, 4);
	return $int;
}

# convert an array (not hash) to a string of bytes
function array_to_raw($data) {
	$ret = to_raw_int(count($data));
	foreach($data as $dat) {
		$ret .= to_raw_int(strlen($dat));
		$ret .= $dat;
	}
	return $ret;
}

function raw_to_array($data) {
	$header_count = pop_int($data);
	$ret = array();
	while($header_count--) {
		$size = pop_int($data);
		$ret[] = substr($data, 0, $size);
		$data = substr($data, $size);
	}
	return $ret;
}