Programming

Hi all,

Thank you all for posting. I have dealt with all endianess issues successfully. The thing is that part of code with the nested structs is quite old so writing it is probably the best thing to do. I will re-arrange the structure so that the largest elements are first, as achenle suggests and if this does not work I will try to break the struct to seperate parts

Also, whatever compiler you're using, look at "#pragma align ...." and "#pragma pack ...", as they're both very useful here.

And watch your compilation options, especially those regarding optimizations. One common optimization is placing fields on the "best" alignment, which could easily be different on different hardware. In particular, the Sun/Oracle Studio compiler suite has the "-fast" optimization option, and that implicitly changes data structure alignment and packing.

The quickest way to check if you have a problem is simply to check the size of the structure using sizeof(). If you get different results on SPARC than you do on x86, obviously the structures aren't aligned the same. If you arrange the elements largest-to-smallest and get the same sizes, you almost certainly have an identical layout on both.

Thanks achenle.

I solved my problem in 2 different ways: (1) by inserting, for the INTEL architecture, some extra 32-bit padding members in my struct and (2) by re-aligining my struct members from largest (64-bit) to smallest (8-bit).

I observed that only SPARC performed padding. It was interesting to see that INTEL did not perform any padding at all... This is why I inserted the extra padding in the INTEL struct!

Sorry, but you are still missing the point. You cannot safely pass structures between disparate platforms. You may get away with it on occasion between two particular platforms with two particular compilers but the way you intend doing it is not portable and will come back to bite you.

As other have suggested, check out serialization/deserialization and marshalling/unmarshalling techniques.

You sure can - if you know what you're doing.

Else things wouldn't work - say, like the ENTIRE internet.

What's a TCP packet? A structure. Passed between multiple types of platforms. From the bulk of the available evidence, quite successfully, too.