| Message ID | Pine.LNX.4.64.0908012148420.25693@ask.diku.dk (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Douglas Landgraf |
| Headers | show |
On Saturday 01 August 2009 21:49:04 Julia Lawall wrote: > From: Julia Lawall <julia@diku.dk> > > The kernel.h macro DIV_ROUND_CLOSEST performs the computation (x + d/2)/d > but is perhaps more readable. > > The semantic patch that makes this change is as follows: > (http://www.emn.fr/x-info/coccinelle/) > > // <smpl> > @haskernel@ > @@ > > #include <linux/kernel.h> > > @depends on haskernel@ > expression x,__divisor; > @@ > > - (((x) + ((__divisor) / 2)) / (__divisor)) > + DIV_ROUND_CLOSEST(x,__divisor) > // </smpl> > > Signed-off-by: Julia Lawall <julia@diku.dk> > > --- > drivers/media/video/uvc/uvc_v4l2.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/media/video/uvc/uvc_v4l2.c > b/drivers/media/video/uvc/uvc_v4l2.c index 87cb9cc..6edaaf6 100644 > --- a/drivers/media/video/uvc/uvc_v4l2.c > +++ b/drivers/media/video/uvc/uvc_v4l2.c > @@ -95,7 +95,7 @@ static __u32 uvc_try_frame_interval(struct uvc_frame > *frame, __u32 interval) const __u32 max = frame->dwFrameInterval[1]; > const __u32 step = frame->dwFrameInterval[2]; > > - interval = min + (interval - min + step/2) / step * step; > + interval = min + DIV_ROUND_CLOSEST(interval-min, step) * step; > if (interval > max) > interval = max; > } The purpose of the above code is to clamp the interval value to the [min, max] range at round it to the closest multiple of step. Other drivers might need similar code. Do you think it might be useful to introduce a clamp_step macro for this ? If not, Acked-by: Laurent Pinchart <laurent.pinchart@skynet.be> Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, 1 Aug 2009, Laurent Pinchart wrote: > On Saturday 01 August 2009 21:49:04 Julia Lawall wrote: > > From: Julia Lawall <julia@diku.dk> > > > > The kernel.h macro DIV_ROUND_CLOSEST performs the computation (x + d/2)/d > > but is perhaps more readable. > > > > The semantic patch that makes this change is as follows: > > (http://www.emn.fr/x-info/coccinelle/) > > > > // <smpl> > > @haskernel@ > > @@ > > > > #include <linux/kernel.h> > > > > @depends on haskernel@ > > expression x,__divisor; > > @@ > > > > - (((x) + ((__divisor) / 2)) / (__divisor)) > > + DIV_ROUND_CLOSEST(x,__divisor) > > // </smpl> > > > > Signed-off-by: Julia Lawall <julia@diku.dk> > > > > --- > > drivers/media/video/uvc/uvc_v4l2.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/media/video/uvc/uvc_v4l2.c > > b/drivers/media/video/uvc/uvc_v4l2.c index 87cb9cc..6edaaf6 100644 > > --- a/drivers/media/video/uvc/uvc_v4l2.c > > +++ b/drivers/media/video/uvc/uvc_v4l2.c > > @@ -95,7 +95,7 @@ static __u32 uvc_try_frame_interval(struct uvc_frame > > *frame, __u32 interval) const __u32 max = frame->dwFrameInterval[1]; > > const __u32 step = frame->dwFrameInterval[2]; > > > > - interval = min + (interval - min + step/2) / step * step; > > + interval = min + DIV_ROUND_CLOSEST(interval-min, step) * step; > > if (interval > max) > > interval = max; > > } > > The purpose of the above code is to clamp the interval value to the [min, max] > range at round it to the closest multiple of step. Other drivers might need > similar code. Do you think it might be useful to introduce a clamp_step macro > for this ? I tried searching for the following: @@ expression interval, min, max, step, E; @@ * interval = min + (interval - min + step/2) / step * step; ... when != interval = E * if (interval > max) { ... interval = max; ... } @@ expression interval, min, max, step, E; @@ * interval = min + DIV_ROUND_CLOSEST(interval-min, step) * step; ... when != interval = E * if (interval > max) { ... interval = max; ... } and the only occurrence I found was the code above. Perhaps there is some other way in which the pattern would appear? julia -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/media/video/uvc/uvc_v4l2.c b/drivers/media/video/uvc/uvc_v4l2.c index 87cb9cc..6edaaf6 100644 --- a/drivers/media/video/uvc/uvc_v4l2.c +++ b/drivers/media/video/uvc/uvc_v4l2.c @@ -95,7 +95,7 @@ static __u32 uvc_try_frame_interval(struct uvc_frame *frame, __u32 interval) const __u32 max = frame->dwFrameInterval[1]; const __u32 step = frame->dwFrameInterval[2]; - interval = min + (interval - min + step/2) / step * step; + interval = min + DIV_ROUND_CLOSEST(interval-min, step) * step; if (interval > max) interval = max; }