Structure Padding Tool

[readysetgo]

Hi everyone,

I am interested in a tool that parses through all the structs in my header files and determines where structure "padding" would be needed. For instance:

struct example {
char c1;
short s1;
char c2;
long l1;
char c3;
}

I would the above to be converted to:

c1
padding byte
s1 byte 1
s1 byte 2
c2
padding byte
padding byte
padding byte
l1 byte 1
l1 byte 2
l1 byte 3
l1 byte 4
c3
padding byte
padding byte
padding byte

I am not interested in re-arranging the fields, but rather add "pad" variables. Do you know if this tool exists? If not, do you have an idea on how this would be implemented?

Thank you.

[PanGalactic]

For which platform? Which compiler? 32-bit or 64-bit? What about compiler options, pragmas or attributes?

http://gcc.gnu.org/onlinedocs/gcc/Structure_002dPacking-Pragmas.html
http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html
http://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#Code-Gen-Options

Is this practical? Is it even possible to do in a portable manner?

[moorecm]

Sounds nuts...

[readysetgo]

Ahh I see, looks like it is not very portable. I am sort of looking for something similar to Perl's pstruct, which prints the offset and size of each variable in a structure, taking in consideration where it would be padded.

http://perldoc.perl.org/pstruct.html

[kbw]

You can vary the padding in C/C++. You can check the padding yourself by comparing the addresses of the fields and the size of the preceding item.