On Fri, Nov 13, 2015 at 6:40 AM, Michael Niedermayer
<mich...@niedermayer.cc> wrote:
> On Thu, Nov 12, 2015 at 09:46:04PM -0500, Ganesh Ajjanagadde wrote:
>> The rationale for this function is reflected in the documentation for
>> it, and is copied here:
>>
>> Clip a double value into the long long amin-amax range.
>> This function is needed because conversion of floating point to integers when
>> it does not fit in the integer's representation does not necessarily saturate
>> correctly (usually converted to a cvttsd2si on x86) which saturates numbers
>> > INT64_MAX to INT64_MIN. The standard marks such conversions as undefined
>> behavior, allowing this sort of mathematically bogus conversions. This
>> provides
>> a safe alternative that is slower obviously but assures safety and better
>> mathematical behavior.
>> API:
>> @param a value to clip
>> @param amin minimum value of the clip range
>> @param amax maximum value of the clip range
>> @return clipped value
>>
>> Note that a priori if one can guarantee from the calling side that the
>> double is in range, it is safe to simply do an explicit/implicit cast,
>> and that will be far faster. However, otherwise this function should be
>> used.
>>
>> avutil minor version is bumped.
>>
>> Reviewed-by: Ronald S. Bultje <rsbul...@gmail.com>
>> Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com>
>> ---
>> libavutil/common.h | 31 +++++++++++++++++++++++++++++++
>> libavutil/version.h | 4 ++--
>> 2 files changed, 33 insertions(+), 2 deletions(-)
>>
>> diff --git a/libavutil/common.h b/libavutil/common.h
>> index 6f0f582..4f60e72 100644
>> --- a/libavutil/common.h
>> +++ b/libavutil/common.h
>> @@ -298,6 +298,34 @@ static av_always_inline av_const double
>> av_clipd_c(double a, double amin, double
>> else return a;
>> }
>>
>> +/**
>> + * Clip and convert a double value into the long long amin-amax range.
>> + * This function is needed because conversion of floating point to integers
>> when
>> + * it does not fit in the integer's representation does not necessarily
>> saturate
>> + * correctly (usually converted to a cvttsd2si on x86) which saturates
>> numbers
>> + * > INT64_MAX to INT64_MIN. The standard marks such conversions as
>> undefined
>> + * behavior, allowing this sort of mathematically bogus conversions. This
>> provides
>> + * a safe alternative that is slower obviously but assures safety and better
>> + * mathematical behavior.
>> + * @param a value to clip
>> + * @param amin minimum value of the clip range
>> + * @param amax maximum value of the clip range
>> + * @return clipped value
>> + */
>> +static av_always_inline av_const int64_t av_rint64_clip_c(double a, int64_t
>> amin, int64_t amax)
>> +{
>> +#if defined(HAVE_AV_CONFIG_H) && defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
>> + if (amin > amax) abort();
>> +#endif
>> + // INT64_MAX+1,INT64_MIN are exactly representable as IEEE doubles
>> + if (a >= 9223372036854775808.0)
>> + return INT64_MAX;
>> + if (a <= INT64_MIN)
>> + return INT64_MIN;
>> + // Finally safe to call av_clipd_c
>> + return (int64_t)av_clipd_c(a, amin, amax);
>> +}
>
> this fails to build here:
Does not get compiled on my machine, that is why I missed this. Very
strange, stdint is included in this header. Can you tell me what to
pass to configure in order to reproduce this?
>
> CXX libavcodec/libutvideodec.o
> cc1plus: warning: command line option ‘-Wdeclaration-after-statement’ is
> valid for C/ObjC but not for C++ [enabled by default]
> cc1plus: warning: command line option ‘-Wmissing-prototypes’ is valid for
> Ada/C/ObjC but not for C++ [enabled by default]
> cc1plus: warning: command line option ‘-Wno-pointer-to-int-cast’ is valid for
> C/ObjC but not for C++ [enabled by default]
> cc1plus: warning: command line option ‘-Wstrict-prototypes’ is valid for
> Ada/C/ObjC but not for C++ [enabled by default]
> cc1plus: warning: command line option ‘-Wno-format-zero-length’ is valid for
> C/ObjC but not for C++ [enabled by default]
> cc1plus: warning: command line option ‘-Wno-pointer-sign’ is valid for C/ObjC
> but not for C++ [enabled by default]
> cc1plus: warning: command line option ‘-std=c99’ is valid for C/ObjC but not
> for C++ [enabled by default]
> libavcodec/libutvideodec.cpp:59:18: warning: multi-character character
> constant [-Wmultichar]
> libavcodec/libutvideodec.cpp:64:18: warning: multi-character character
> constant [-Wmultichar]
> libavcodec/libutvideodec.cpp:69:18: warning: multi-character character
> constant [-Wmultichar]
> libavcodec/libutvideodec.cpp:73:18: warning: multi-character character
> constant [-Wmultichar]
> libavcodec/libutvideodec.cpp:86:18: warning: multi-character character
> constant [-Wmultichar]
> libavcodec/libutvideodec.cpp:98:19: warning: multi-character character
> constant [-Wmultichar]
> In file included from ./libavutil/avutil.h:288:0,
> from ./libavutil/samplefmt.h:24,
> from libavcodec/avcodec.h:31,
> from libavcodec/libutvideodec.cpp:29:
> ./libavutil/common.h: In function ‘int64_t av_rint64_clip_c(double, int64_t,
> int64_t)’:
> ./libavutil/common.h:322:16: error: ‘INT64_MAX’ was not declared in this scope
> ./libavutil/common.h:323:14: error: ‘INT64_MIN’ was not declared in this scope
> libavcodec/libutvideodec.cpp: In function ‘int
> utvideo_decode_init(AVCodecContext*)’:
> libavcodec/libutvideodec.cpp:96:21: warning: ‘int
> avpicture_get_size(AVPixelFormat, int, int)’ is deprecated (declared at
> libavcodec/avcodec.h:4814) [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:96:83: warning: ‘int
> avpicture_get_size(AVPixelFormat, int, int)’ is deprecated (declared at
> libavcodec/avcodec.h:4814) [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:109:12: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:109:12: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:115:12: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:115:12: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:118:12: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:118:12: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp: In function ‘int
> utvideo_decode_frame(AVCodecContext*, void*, int*, AVPacket*)’:
> libavcodec/libutvideodec.cpp:144:27: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:144:27: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp: In function ‘int
> utvideo_decode_close(AVCodecContext*)’:
> libavcodec/libutvideodec.cpp:236:27: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> libavcodec/libutvideodec.cpp:236:27: warning: ‘AVCodecContext::coded_frame’
> is deprecated (declared at libavcodec/avcodec.h:2892)
> [-Wdeprecated-declarations]
> make: *** [libavcodec/libutvideodec.o] Error 1
>
>
> [...]
>
> --
> Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Into a blind darkness they enter who follow after the Ignorance,
> they as if into a greater darkness enter who devote themselves
> to the Knowledge alone. -- Isha Upanishad
>
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