Messages in this thread | | | Date | Mon, 14 Dec 2009 16:47:41 -0800 | From | Greg KH <> | Subject | Re: [PATCH] staging: s5k3e2fx.c: reduce complexity by factoring |
| |
On Mon, Dec 14, 2009 at 04:38:40PM -0800, Justin Madru wrote: > On 12/09/2009 01:57 AM, Dan Carpenter wrote: > > On Sat, Dec 05, 2009 at 06:03:20PM -0800, Justin Madru wrote: > > > >> I was style fixing some code when I ran into this code. > >> It seems like the code could be reduced, by factoring the expression. > >> But this results in a very simple expression. > >> > >> Am I assuming something wrong? Or is this a bug in the original code? > >> This doesn't look right because the assignment of s_move[i] has no mention > >> of the loop counter. > >> > >> Justin > >> > >> ------ > >> > >> the code was looping, seting s_move[i] to the following calculations > >> > >> if (actual_step>= 0) > >> s_move[i] = ((((i + 1) * gain + 0x200) - (i * gain + 0x200)) / 0x400); > >> else > >> s_move[i] = ((((i + 1) * gain - 0x200) - (i * gain - 0x200)) / 0x400); > >> > >> but, by factoring the expression, it can be shown that they both reduce > >> to a very simple expression: > >> > >> s_move[i] = gain / 0x400; > >> > >> > > Heh. > > > > Looks like an improvement to me. > > > > If gain were 16 bits instead of 32 I would think the "* 0x400 / 0x400" was > > designed to mask out the highest 10 bits. > > > > Acked-by: Dan Carpenter<error27@gmail.com> > > > > regards, > > dan carpenter > > > > > >> Signed-off-by: Justin Madru<jdm64@gawab.com> > >> --- > >> drivers/staging/dream/camera/s5k3e2fx.c | 10 +++------- > >> 1 files changed, 3 insertions(+), 7 deletions(-) > >> > >> diff --git a/drivers/staging/dream/camera/s5k3e2fx.c b/drivers/staging/dream/camera/s5k3e2fx.c > >> index f0e49be..d205a2d 100644 > >> --- a/drivers/staging/dream/camera/s5k3e2fx.c > >> +++ b/drivers/staging/dream/camera/s5k3e2fx.c > >> @@ -1092,14 +1092,10 @@ static int32_t s5k3e2fx_move_focus(int direction, int32_t num_steps) > >> > >> actual_step = step_direction * (int16_t)num_steps; > >> pos_offset = init_code + s5k3e2fx_ctrl->curr_lens_pos; > >> - gain = actual_step * 0x400 / 5; > >> + gain = actual_step / 5; > >> > >> - for (i = 0; i<= 4; i++) { > >> - if (actual_step>= 0) > >> - s_move[i] = ((((i+1)*gain+0x200) - (i*gain+0x200))/0x400); > >> - else > >> - s_move[i] = ((((i+1)*gain-0x200) - (i*gain-0x200))/0x400); > >> - } > >> + for (i = 0; i<= 4; i++) > >> + s_move[i] = gain; > >> > >> /* Ring Damping Code */ > >> for (i = 0; i<= 4; i++) { > >> -- > >> 1.6.5.4 > >> > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > >> the body of a message to majordomo@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > >> Please read the FAQ at http://www.tux.org/lkml/ > >> > > I've yet to see a reply from GregH. Has this patch been misplaced or > dropped? > Or is the patch no longer valid/correct?
It's in my "to-apply" queue. I was working on the .33-rc1 merge first. After that comes out I'll get to my patch queue.
thanks,
greg k-h
| |