src/Helpers/BinaryStringHelper.php
<?php
namespace RouterOS\Helpers;
/**
* class BinaryStringHelper
*
* Strings and binary data manipulations
*
* @package RouterOS\Helpers
* @since 0.9
*/
class BinaryStringHelper
{
/**
* Convert an integer value in a "Network Byte Ordered" binary string (most significant value first)
*
* Reads the integer, starting from the most significant byte, one byte a time.
* Once reach a non 0 byte, construct a binary string representing this values
* ex :
* 0xFF7 => chr(0x0F).chr(0xF7)
* 0x12345678 => chr(0x12).chr(0x34).chr(0x56).chr(0x76)
* Compatible with 8, 16, 32, 64 etc.. bits systems
*
* @see https://en.wikipedia.org/wiki/Endianness
* @param int|float $value the integer value to be converted
* @return string the binary string
*/
public static function IntegerToNBOBinaryString($value): string
{
// Initialize an empty string
$buffer = '';
// Lets start from the most significant byte
for ($i = (PHP_INT_SIZE - 1); $i >= 0; $i--) {
// Prepare a mask to keep only the most significant byte of $value
$mask = 0xFF << ($i * 8);
// If the most significant byte is not 0, the final string must contain it
// If we have already started to construct the string (i.e. there are more signficant digits)
// we must set the byte, even if it is a 0.
// 0xFF00FF, for example, require to set the second byte byte with a 0 value
if (($value & $mask) || $buffer !== '') {
// Get the current byte by shifting it to least significant position and add it to the string
// 0xFF12345678 => 0xFF
$byte = $value >> (8 * $i);
$buffer .= chr($byte);
// Set the most significant byte to 0 so we can restart the process being shure
// that the value is left padded with 0
// 0xFF12345678 => 0x12345678
// -1 = 0xFFFFF.... (number of F depend of PHP_INT_SIZE )
$mask = -1 >> ((PHP_INT_SIZE - $i) * 8);
$value &= $mask;
}
}
// Special case, 0 will not fill the buffer, have to construct it manualy
if (0 === $value) {
$buffer = chr(0);
}
return $buffer;
}
}