On Mon, Aug 13, 2012 at 1:18 PM, Måns Rullgård <m...@mansr.com> wrote:
> aviad rozenhek <avia...@gmail.com> writes: > > >> > >> unary minus operator applied to unsigned type, result still unsigned > > > > I get this compiler warning when using any if the specialized AVERROR_XXX > > macros, like AVERROR_BSF_NOT_FOUND or AVERROR_DECODER_NOT_FOUND. > > > > the reason is because > > > >> #define AVERROR_BSF_NOT_FOUND (-MKTAG(0xF8,'B','S','F')) ///< > >> Bitstream filter not found > > > > and the result from MKTAG is *unsigned* . > > Well, that's bad. > > > therefore I suggest to change the code thusly: > > > > #define DEFINE_AVERROR(a, b, c, d) (-(int32_t)MKTAG(a, b, c, d)) > > That conversion is undefined, so it's no good. The correct solution is > to define the error code in such a way that it is properly signed from > the start. MKTAG(-7,'B','S','F') might do it. > > hmm... If I read it correctly, MKTAG is unsigned by definition, regardless of input > #define MKTAG(a,b,c,d) ((a) | ((b) << 8) | ((c) << 16) | ((*unsigned*)(d) > << 24)) -- Aviad Rozenhek
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