Re: How to create a Win32::API::Struct struct if the struct has union in it?

On 11/30/2011 14:52, Cosimo Streppone wrote:
> On Sun, 27 Nov 2011 02:29:01 +0100, Burak Gürsoy <[email protected]> wrote:
>
>> I'm wondering about how to create a SYSTEM_INFO structure from Perl:
>>
>> http://msdn.microsoft.com/en-us/library/windows/desktop/ms724958(v=vs.85).aspx
>>
>> to pass this to GetNativeSystemInfo(). Win32::API::Struct->typedef()
>> seems to support
>> simple structs only. Is there a way to create such a nested struct?
>
> Sorry, no idea...

Since there is no union logic in the module, the easiest thing to
do is replace the union with whatever variant that allows you to
access the data the way you want.  It's hard enough to even figure
out from M$ docs how to actually pack a structure (no clear 100%
exact algorithm).  Apparently it's a choice that can also be
altered by compiler options.

Personally, I'd have made structure packing a hard and fast
algorithm to avoid some of these issues created by different
CPU architectures, but then again - can all CPUs follow the
algorithm you create ?

EG:
	typedef Win32::API::Struct SYSTEM_INFO => qw(
	  WORD wProcessorArchitecture;
	  WORD wReserved;
	  DWORD  dwPageSize;
	  LPVOID lpMinimumApplicationAddress;
	  LPVOID lpMaximumApplicationAddress;
	  DWORD  dwActiveProcessorMask;
	  DWORD  dwNumberOfProcessors;
	  DWORD  dwProcessorType;
	  DWORD  dwAllocationGranularity;
	  WORD  wProcessorLevel;
	  WORD  wProcessorRevision;
	);