Question

So i’m making a class in PHP to parse the VPK file format.

However i’ve hit a problem:

object(VPKHeader)#2 (3) {
    ["Signature"]=>
  string(8) "3412aa55"
    ["Version"]=>
  string(4) "1000"
    ["DirectoryLength"]=>
  int(832512)
}

The signature is supposed to be 0x55aa1234, however the signature I’m reading is 0x3412aa55.

How do I switch the endianness in PHP?

Answer 1

If your hex values will always be strings, you can use the following function :

function swapEndianness($hex) {
    return implode('', array_reverse(str_split($hex, 2)));
}

Agreed, it’s not the most efficient, but the code is quite elegant in my opinion. Also, it works with all sizes of numbers.