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.
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.
Arnd