%PDF-
%PDF-
Mini Shell
Mini Shell
<?php
namespace IPLib\Service;
/**
* Helper class to work with unsigned integers.
*
* @internal
*/
class UnsignedIntegerMath
{
/**
* Convert a string containing a decimal, octal or hexadecimal number into its bytes.
*
* @param string $value
* @param int $numBytes the wanted number of bytes
* @param bool $onlyDecimal Only parse decimal numbers
*
* @return int[]|null
*/
public function getBytes($value, $numBytes, $onlyDecimal = false)
{
$m = null;
if ($onlyDecimal) {
if (preg_match('/^0*(\d+)$/', $value, $m)) {
return $this->getBytesFromDecimal($m[1], $numBytes);
}
} else {
if (preg_match('/^0[Xx]0*([0-9A-Fa-f]+)$/', $value, $m)) {
return $this->getBytesFromHexadecimal($m[1], $numBytes);
}
if (preg_match('/^0+([0-7]*)$/', $value, $m)) {
return $this->getBytesFromOctal($m[1], $numBytes);
}
if (preg_match('/^[1-9][0-9]*$/', $value)) {
return $this->getBytesFromDecimal($value, $numBytes);
}
}
// Not a valid number
return null;
}
/**
* @return int
*/
protected function getMaxSignedInt()
{
return PHP_INT_MAX;
}
/**
* @param string $value never zero-length, never extra leading zeroes
* @param int $numBytes
*
* @return int[]|null
*/
private function getBytesFromBits($value, $numBytes)
{
$valueLength = strlen($value);
if ($valueLength > $numBytes << 3) {
// overflow
return null;
}
$remainderBits = $valueLength % 8;
if ($remainderBits !== 0) {
$value = str_pad($value, $valueLength + 8 - $remainderBits, '0', STR_PAD_LEFT);
}
$bytes = array_map('bindec', str_split($value, 8));
return array_pad($bytes, -$numBytes, 0);
}
/**
* @param string $value may be zero-length, never extra leading zeroes
* @param int $numBytes
*
* @return int[]|null
*/
private function getBytesFromOctal($value, $numBytes)
{
if ($value === '') {
return array_fill(0, $numBytes, 0);
}
$bits = implode(
'',
array_map(
function ($octalDigit) {
return str_pad(decbin(octdec($octalDigit)), 3, '0', STR_PAD_LEFT);
},
str_split($value, 1)
)
);
$bits = ltrim($bits, '0');
return $bits === '' ? array_fill(0, $numBytes, 0) : static::getBytesFromBits($bits, $numBytes);
}
/**
* @param string $value never zero-length, never extra leading zeroes
* @param int $numBytes
*
* @return int[]|null
*/
private function getBytesFromDecimal($value, $numBytes)
{
$valueLength = strlen($value);
$maxSignedIntLength = strlen((string) $this->getMaxSignedInt());
if ($valueLength < $maxSignedIntLength) {
return $this->getBytesFromBits(decbin((int) $value), $numBytes);
}
// Divide by two, so that we have 1 less bit
$carry = 0;
$halfValue = ltrim(
implode(
'',
array_map(
function ($digit) use (&$carry) {
$number = $carry + (int) $digit;
$carry = ($number % 2) * 10;
return (string) $number >> 1;
},
str_split($value, 1)
)
),
'0'
);
$halfValueBytes = $this->getBytesFromDecimal($halfValue, $numBytes);
if ($halfValueBytes === null) {
return null;
}
$carry = $carry === 0 ? 0 : 1;
$result = array_fill(0, $numBytes, 0);
for ($index = $numBytes - 1; $index >= 0; $index--) {
$byte = $carry + ($halfValueBytes[$index] << 1);
if ($byte <= 0xFF) {
$carry = 0;
} else {
$carry = ($byte & ~0xFF) >> 8;
$byte -= 0x100;
}
$result[$index] = $byte;
}
if ($carry !== 0) {
// Overflow
return null;
}
return $result;
}
/**
* @param string $value never zero-length, never extra leading zeroes
* @param int $numBytes
*
* @return int[]|null
*/
private function getBytesFromHexadecimal($value, $numBytes)
{
$valueLength = strlen($value);
if ($valueLength > $numBytes << 1) {
// overflow
return null;
}
$value = str_pad($value, $valueLength + $valueLength % 2, '0', STR_PAD_LEFT);
$bytes = array_map('hexdec', str_split($value, 2));
return array_pad($bytes, -$numBytes, 0);
}
}
Zerion Mini Shell 1.0