- substr: documentation ( source)
- var_dump: documentation ( source)
- current: documentation ( source)
- unpack: documentation ( source)
<?php
const INT_SIGNED = 1;
const INT_LE = 2;
function unpack_int32($str, $flags = 0) {
$length = strlen($str);
if ($length < 4) {
return false;
} else if ($length > 4) {
$str = substr($str, 0, 4);
}
$format = ($flags & INT_LE) ? 'V' : 'N';
$result = current(unpack($format, $str));
$signBit = (bool) ($result & 0x80000000);
$isSigned = (bool) ($flags & INT_SIGNED);
$is32bit = PHP_INT_MAX < 0x80000000;
if ($signBit && $isSigned && !$is32bit) {
$result = 0xFFFFFFFF00000000 | $result;
} else if ($signBit && !$isSigned && $is32bit) {
$result = (($result & 0x7FFFFFFF) * 2) + ~$result + 1;
}
return $result;
}
var_dump(unpack_int32("\x81\x00\x00\x80", INT_SIGNED | INT_LE));