[FFmpeg-devel] [PATCH 1/4] lavu: add simple array implementation

[Nicolas George]

Le quintidi 15 ventôse, an CCXXII, Nicolas George a écrit :
> For that issue, I would conclude: let us not discuss without actually seeing
> the code.

And since it is always better to have something concrete to discuss about,
here is a first draft:

#define AV_DYNARRAY_ADD(av_size_max, av_array, av_size, av_success, av_failure) \
    do { \
        size_t av_size_new = av_size; \
        if (!(av_size & (av_size - 1))) { \
            av_size_new = av_size ? av_size << 1 : 1; \
            if (av_size_new > av_size_max) { \
                av_size_new = 0; \
            } else { \
                void *av_array_new = \
                    av_realloc(tab, av_size_new * sizeof(*av_array)); \
                if (!av_array_new) \
                    av_size_new = 0; \
                else \
                    av_array = av_array_new; \
            } \
        } \
        if (av_size_new) { \
            av_success; \
            av_size++; \
        } else { \
            av_failure; \
        } \
    } while (0)

I realize that the types (of the size and of the elements) were actually not
needed, even with type-safe code.

This is not tested, I have no time to do it right now, but it can still
serve as a base for discussion.

Possible enhancements:

* Check for (size & (size + 1)) == 0 and resize to 2*size+1: that would give
  successive sizes 1, 3, 5, 7, 15, ... 0x7FFFFFxx instead of 1, 2, 4, ...
  0x40000000.

* Add a size_min argument, to avoid allocating tiny arrays.

Regards,

-- 
  Nicolas George
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