On Thu, Oct 15, 2015 at 11:21 PM, Ronald S. Bultje <rsbul...@gmail.com> wrote: > Hi, > > On Thu, Oct 15, 2015 at 8:37 PM, Ganesh Ajjanagadde <gajja...@mit.edu> > wrote: > >> Hi all, >> >> Examining libavutil/macros, there is AV_GLUE/AV_JOIN (why are there >> two?) defined for preprocessor token pasting. However, it is not being >> used anywhere, instead people have use "##". There are a number of >> options regarding this: >> 1. Start using them, and convert the ## usage to AV_GLUE/AV_JOIN. >> 2. Don't bother at all. >> 3. Deprecate and remove them at some point. >> > > ../libavcodec/flacdsp_lpc_template.c:#define FUNC(n) AV_JOIN(n ## _, > SAMPLE_SIZE) > ../libavcodec/flacdsp_template.c:# define FSUF AV_JOIN(SAMPLE_SIZE, p) > ../libavcodec/flacdsp_template.c:#define FUNC(n) AV_JOIN(n ## _, FSUF) > ../libavcodec/h264_mb_template.c:# define FUNC(n) AV_JOIN(n ## _simple_, > BITS) > > You have to understand _why_ we use this. The problem is that in some cases > (sometimes in a compiler-dependent way, other times more generally), you > need to expand preprocessor tokens before concatenating them. Older > versions of MSVC were bad at this, but you can see gcc suffers from it also > if you look for uses of cat() in > libavcodec/x86/vp9dsp_init_16bpp_template.c. If you change cat into just > ##, it stops working. > > And yes, cat, should probably be AV_JOIN, I forgot about AV_JOIN.
Got it, thanks. I still suppose AV_GLUE is redundant (isn't it the same as AV_JOIN in all these use cases?). > > Ronald > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
