[FFmpeg-devel] [PATCHv2] all: fix enum definition for large values

[Ronald S. Bultje]

Hi,

On Tue, Oct 27, 2015 at 10:58 PM, Ganesh Ajjanagadde <gajjanagadde at gmail.com
> wrote:

> On Tue, Oct 27, 2015 at 10:41 PM, Ronald S. Bultje <rsbultje at gmail.com>
> wrote:
> > Hi,
> >
> > On Tue, Oct 27, 2015 at 8:53 PM, Ganesh Ajjanagadde <
> gajjanagadde at gmail.com>
> > wrote:
> >>
> >> ISO C restricts enumerator values to the range of int. Thus (for
> instance)
> >> 0x80000000
> >> unfortunately does not work, and throws a warning with -Wpedantic on
> >> clang 3.7.
> >>
> >> This fixes it by using alternative expressions that result in identical
> >> values but do not have this issue.
> >>
> >> Tested with FATE.
> >>
> >> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> >> ---
> >>  libavcodec/dca_syncwords.h | 26 ++++++++++++--------------
> >>  libavformat/cinedec.c      |  2 +-
> >>  libavformat/mov_chan.c     |  2 +-
> >>  3 files changed, 14 insertions(+), 16 deletions(-)
> >>
> >> diff --git a/libavcodec/dca_syncwords.h b/libavcodec/dca_syncwords.h
> >> index 3466b6b..6981cb8 100644
> >> --- a/libavcodec/dca_syncwords.h
> >> +++ b/libavcodec/dca_syncwords.h
> >> @@ -19,19 +19,17 @@
> >>  #ifndef AVCODEC_DCA_SYNCWORDS_H
> >>  #define AVCODEC_DCA_SYNCWORDS_H
> >>
> >> -enum DCASyncwords {
> >> -    DCA_SYNCWORD_CORE_BE        = 0x7FFE8001U,
> >> -    DCA_SYNCWORD_CORE_LE        = 0xFE7F0180U,
> >> -    DCA_SYNCWORD_CORE_14B_BE    = 0x1FFFE800U,
> >> -    DCA_SYNCWORD_CORE_14B_LE    = 0xFF1F00E8U,
> >> -    DCA_SYNCWORD_XCH            = 0x5A5A5A5AU,
> >> -    DCA_SYNCWORD_XXCH           = 0x47004A03U,
> >> -    DCA_SYNCWORD_X96            = 0x1D95F262U,
> >> -    DCA_SYNCWORD_XBR            = 0x655E315EU,
> >> -    DCA_SYNCWORD_LBR            = 0x0A801921U,
> >> -    DCA_SYNCWORD_XLL            = 0x41A29547U,
> >> -    DCA_SYNCWORD_SUBSTREAM      = 0x64582025U,
> >> -    DCA_SYNCWORD_SUBSTREAM_CORE = 0x02B09261U,
> >> -};
> >> +#define    DCA_SYNCWORD_CORE_BE              0x7FFE8001U
> >> +#define    DCA_SYNCWORD_CORE_LE              0xFE7F0180U
> >> +#define    DCA_SYNCWORD_CORE_14B_BE          0x1FFFE800U
> >> +#define    DCA_SYNCWORD_CORE_14B_LE          0xFF1F00E8U
> >> +#define    DCA_SYNCWORD_XCH                  0x5A5A5A5AU
> >> +#define    DCA_SYNCWORD_XXCH                 0x47004A03U
> >> +#define    DCA_SYNCWORD_X96                  0x1D95F262U
> >> +#define    DCA_SYNCWORD_XBR                  0x655E315EU
> >> +#define    DCA_SYNCWORD_LBR                  0x0A801921U
> >> +#define    DCA_SYNCWORD_XLL                  0x41A29547U
> >> +#define    DCA_SYNCWORD_SUBSTREAM            0x64582025U
> >> +#define    DCA_SYNCWORD_SUBSTREAM_CORE       0x02B09261U
> >
> >
> > This one is fine.
> >
> >>
> >> --- a/libavformat/cinedec.c
> >> +++ b/libavformat/cinedec.c
> >> @@ -50,7 +50,7 @@ enum {
> >>      CFA_BAYER     = 3,  /**< GB/RG */
> >>      CFA_BAYERFLIP = 4,  /**< RG/GB */
> >>
> >> -    CFA_TLGRAY    = 0x80000000,
> >> +    CFA_TLGRAY    = INT32_MIN,
> >>      CFA_TRGRAY    = 0x40000000,
> >>      CFA_BLGRAY    = 0x20000000,
> >>      CFA_BRGRAY    = 0x10000000
> >> diff --git a/libavformat/mov_chan.c b/libavformat/mov_chan.c
> >> index a2fa8d6..f6181e2 100644
> >> --- a/libavformat/mov_chan.c
> >> +++ b/libavformat/mov_chan.c
> >> @@ -45,7 +45,7 @@
> >>   *            do not specify a particular ordering of those channels."
> >>   */
> >>  enum MovChannelLayoutTag {
> >> -    MOV_CH_LAYOUT_UNKNOWN               = 0xFFFF0000,
> >> +    MOV_CH_LAYOUT_UNKNOWN               = -( 1 << 16),
> >>      MOV_CH_LAYOUT_USE_DESCRIPTIONS      = (  0 << 16) | 0,
> >>      MOV_CH_LAYOUT_USE_BITMAP            = (  1 << 16) | 0,
> >>      MOV_CH_LAYOUT_DISCRETEINORDER       = (147 << 16) | 0,
> >> --
> >> 2.6.2
> >
> >
> > I personally don't really like these... I think both obfuscate the
> meaning
> > of the flag values, particularly the first one.
>
> There is no real solution (recall apedec and the INT32_MIN final
> solution), barring adding a comment signifying our intent (ie the
> desired hex mask). I can do this if you think it helps.


The solution is to not care about ISO C if it doesn't fix real issues. :)

Ronald