[XviD-devel] how to make struct smaller

[Edouard Gomez]

Radek Czyz (syskin at ihug.com.au) wrote:
> Hi everyone,
> 
> I found away to make MACROBLOCK struct much smaller. How about this:
> 
> typedef struct
> {
>     union {
>         struct {
>             ...
>         };
>         struct {
>             ...
>         };
>     };
>     
> } plop_t;    

This is neither ANSI  C nor ISO C99, union fields have  to be named. But
gcc accepts them in non ISO C modes.

To be valid ISO C 89 or 99, you have to write:

typedef struct
{
    int mode;
                                                                                
    union {
        struct {
            int var1;
            int var2;
        } plop1;
        struct {
            int var3;
            int var4;
            int var5;
        } plop2;
    }megaplopunion;
} plop_t;

So addressing fields becomes quite annoying:
plop_t x;
x.megaplopunion.plop1.var1 = 0;

-- 
Edouard Gomez