Messages in this thread | | | Date | Tue, 12 Nov 2019 21:26:00 +0100 | From | Takashi Iwai <> | Subject | Re: [alsa-devel] [PATCH v6 5/8] ALSA: Avoid using timespec for struct snd_rawmidi_status |
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On Tue, 12 Nov 2019 21:04:10 +0100, Arnd Bergmann wrote: > > On Tue, Nov 12, 2019 at 5:38 PM Takashi Iwai <tiwai@suse.de> wrote: > > On Tue, 12 Nov 2019 16:16:39 +0100, Arnd Bergmann wrote: > > > +#ifndef __KERNEL__ > > > struct snd_rawmidi_status { > > > int stream; > > > + unsigned char pad1[sizeof(time_t) - sizeof(int)]; > > > struct timespec tstamp; /* Timestamp */ > > > size_t avail; /* available bytes */ > > > size_t xruns; /* count of overruns since last status (in bytes) */ > > > unsigned char reserved[16]; /* reserved for future use */ > > > }; > > > > Can we use union instead of padding? Something like: > > > > struct snd_rawmidi_status { > > union { > > int stream; > > time_t stream_alignment; > > }; > > struct timespec tstamp; /* Timestamp */ > > .... > > I think this would work most of the time, though I don't feel this is more > readable than the other version. > > More importantly, it requires compiling user applications with GNU extensions > (--std=gnu89 or higher) or C11, but not C99, so this could be a problem > for some applications.
OK, fair enough.
> If you feel there is a problem with the padding syntax, how about enclosing > it in a typedef like: > > typedef struct { char pad[sizeof(time_t) - sizeof(int)]; } __time_pad; > > This typedef could be used in several structures from the other patches > as well.
Yes, that improves the readability.
thanks,
Takashi
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