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