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<?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));

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