be aware of the behavior of your system that PHP resides on.
On x86, unpack MAY not yield the result you expect for UInt32
This is due to the internal nature of PHP, being that integers are internally stored as SIGNED!
For x86 systems, unpack('N', "\xff\xff\xff\xff") results in -1
For (most?) x64 systems, unpack('N', "\xff\xff\xff\xff") results in 4294967295.
This can be verified by checking the value of PHP_INT_SIZE.
If this value is 4, you have a PHP that internally stores 32-bit.
A value of 8 internally stores 64-bit.
To work around this 'problem', you can use the following code to avoid problems with unpack.
The code is for big endian order but can easily be adjusted for little endian order (also, similar code works for 64-bit integers):
<?php
function _uint32be($bin)
{
if (PHP_INT_SIZE <= 4){
list(,$h,$l) = unpack('n*', $bin);
return ($l + ($h*0x010000));
}
else{
list(,$int) = unpack('N', $bin);
return $int;
}
}
?>
Do note that you *could* also use sprintf('%u', $x) to show the unsigned real value.
Also note that (at least when PHP_INT_SIZE = 4) the result WILL be a float value when the input is larger then 0x7fffffff (just check with gettype);
Hope this helps people.
