lkml.org 
[lkml]   [2014]   [Oct]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRE: [PATCH] 6fire: Convert byte_rev_table uses to bitrev8
> Use the inline function instead of directly indexing the array.
>
> This allows some architectures with hardware instructions for bit reversals
> to eliminate the array.
>
> Signed-off-by: Joe Perches <joe@perches.com>
> ---
> On Sun, 2014-10-26 at 23:46 -0700, Joe Perches wrote:
> > On Mon, 2014-10-27 at 14:37 +0800, Wang, Yalin wrote:
> > > this change add CONFIG_HAVE_ARCH_BITREVERSE config option, so that
> > > we can use arm/arm64 rbit instruction to do bitrev operation by
> > > hardware.
> []
> > > diff --git a/include/linux/bitrev.h b/include/linux/bitrev.h index
> > > 7ffe03f..ef5b2bb 100644
> > > --- a/include/linux/bitrev.h
> > > +++ b/include/linux/bitrev.h
> > > @@ -3,6 +3,14 @@
> > >
> > > #include <linux/types.h>
> > >
> > > +#ifdef CONFIG_HAVE_ARCH_BITREVERSE
> > > +#include <asm/bitrev.h>
> > > +
> > > +#define bitrev32 __arch_bitrev32
> > > +#define bitrev16 __arch_bitrev16
> > > +#define bitrev8 __arch_bitrev8
> > > +
> > > +#else
> > > extern u8 const byte_rev_table[256];
>
> sound/usb/6fire/firmware.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sound/usb/6fire/firmware.c b/sound/usb/6fire/firmware.c index
> 3b02e54..62c25e7 100644
> --- a/sound/usb/6fire/firmware.c
> +++ b/sound/usb/6fire/firmware.c
> @@ -316,7 +316,7 @@ static int usb6fire_fw_fpga_upload(
>
> while (c != end) {
> for (i = 0; c != end && i < FPGA_BUFSIZE; i++, c++)
> - buffer[i] = byte_rev_table[(u8) *c];
> + buffer[i] = bitrev8((u8)*c);
>
> ret = usb6fire_fw_fpga_write(device, buffer, i);
> if (ret < 0) {
>
I think the most safe way is change byte_rev_table[] to be satic,
So that no driver can access it directly,
The build error can remind the developer if they use byte_rev_table[]
Directly .

Thanks


\
 
 \ /
  Last update: 2014-10-29 04:01    [W:0.148 / U:1.308 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site