On Thu, 23 Apr 2009, Julia Lawall wrote:
> I found 8 occurrences with the following Coccinelle semantic match:
>
> @@ expression n; @@
>
> * (n & (n-1)) == 0
>
>
> The most unpleasant was:
>
> (!(((fp)->ipend & ~0x30) & (((fp)->ipend & ~0x30) - 1)))
>
> in the file arch/blackfin/kernel/traps.c.
>
> At least some of them seemed to have comments nearby that suggested
> that searching for a single 1-bit was indeed the goal. I haven't
> looked at all of them, though.
behold, the power of shell and REs, which searches for four
variations of that test:
=====
#!/bin/sh
DIR=${1-*}
echo -e " x & (x - 1):\n"
grep -Ern "([^\(\)]+) ?\& ?\(\1 ?- ?1\)" ${DIR}
echo -e " x & ((x) - 1):\n"
grep -Ern "([^\(\)]+) ?\& ?\(\(\1\) ?- ?1\)" ${DIR}
echo -e " (x) & (x - 1):\n"
grep -Ern "\(([^\(\)]+)\) ?\& ?\(\1 ?- ?1\)" ${DIR}
echo -e " (x) & ((x) - 1):\n"
grep -Ern "\(([^\(\)]+)\) ?\& ?\(\(\1\) ?- ?1\)" ${DIR}
=====
$ find_pow2_cleanup.sh drivers/staging/comedi
x & (x - 1):
drivers/staging/comedi/drivers/amplc_pci224.c:790: if ((cmd->start_src & (cmd->start_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci224.c:792: if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci224.c:794: if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci224.c:796: if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci224.c:798: if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1274: if ((cmd->start_src & (cmd->start_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1276: if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1278: if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1280: if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1282: if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1710: if ((cmd->start_src & (cmd->start_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1712: if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1714: if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1716: if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_pci230.c:1718: if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_dio200.c:843: if ((cmd->start_src & (cmd->start_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_dio200.c:845: if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_dio200.c:847: if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_dio200.c:849: if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
drivers/staging/comedi/drivers/amplc_dio200.c:851: if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmmio.c:1123: if ((cmd->start_src & (cmd->start_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmmio.c:1125: if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmmio.c:1127: if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmmio.c:1129: if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmmio.c:1131: if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmuio.c:1033: if ((cmd->start_src & (cmd->start_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmuio.c:1035: if ((cmd->scan_begin_src & (cmd->scan_begin_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmuio.c:1037: if ((cmd->convert_src & (cmd->convert_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmuio.c:1039: if ((cmd->scan_end_src & (cmd->scan_end_src - 1)) != 0)
drivers/staging/comedi/drivers/pcmuio.c:1041: if ((cmd->stop_src & (cmd->stop_src - 1)) != 0)
x & ((x) - 1):
(x) & (x - 1):
(x) & ((x) - 1):
and that's out of a single subdirectory of drivers/staging. there's
more. lots more.
rday
--
========================================================================
Robert P. J. Day Waterloo, Ontario, CANADA
Linux Consulting, Training and Annoying Kernel Pedantry.
Web page: http://crashcourse.ca
Linked In: http://www.linkedin.com/in/rpjday
Twitter: http://twitter.com/rpjday
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