On Sun, Mar 08, 2015 at 10:32:03PM +0100, Michael Niedermayer wrote: > On Sat, Mar 07, 2015 at 11:44:10PM +0800, zhaoxiu.zeng wrote: > > From 47c997fa0623ab94a7a93b2d2e4cc4fa64c85d5f Mon Sep 17 00:00:00 2001 > > From: Zeng Zhaoxiu <zhaoxiu.z...@gmail.com> > > Date: Sat, 7 Mar 2015 23:26:42 +0800 > > Subject: [PATCH 1/1] avcodec/wmalossless: use av_clip_intp2 > > this breaks build on ARM > > ffmpeg/libavutil/arm/intmath.h:69:5: warning: asm operand 2 probably doesn’t > match constraints > ffmpeg/libavutil/arm/intmath.h:69:5: warning: asm operand 2 probably doesn’t > match constraints > ffmpeg/libavutil/arm/intmath.h:69:5: error: impossible constraint in ‘asm’ > ffmpeg/libavutil/arm/intmath.h:69:5: error: impossible constraint in ‘asm’
ARM uses asm code based on the ssat instruction. That one requires the number of bits to be a constant. This means that for ARM this function may only be used with constant p argument. I guess whether this is ok depends on whether there are other cases/architectures where av_clip_intp2 is actually faster than a normal clip even when p is not constant. The C code doesn't look particularly faster to me in that case, but I haven't tested it. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
