8907f744ff
Two new functions are provided, bit_ffs_at() and bit_ffc_at(), which allow
for efficient searching of set or cleared bits starting from any bit offset
within the bit string.
Performance is improved by operating on longs instead of bytes and using
ffsl() for searches within a long. ffsl() is a compiler builtin in both
clang and gcc for most architectures, converting what was a brute force
while loop search into a couple of instructions.
All of the bitstring(3) API continues to be contained in the header file.
Some of the functions are large enough that perhaps they should be uninlined
and moved to a library, but that is beyond the scope of this commit.
sys/sys/bitstring.h:
Convert the majority of the existing bit string implementation from
macros to inline functions.
Properly protect the implementation from inadvertant macro expansion
when included in a user's program by prefixing all private
macros/functions and local variables with '_'.
Add bit_ffs_at() and bit_ffc_at(). Implement bit_ffs() and
bit_ffc() in terms of their "at" counterparts.
Provide a kernel implementation of bit_alloc(), making the full API
usable in the kernel.
Improve code documenation.
share/man/man3/bitstring.3:
Add pre-exisiting API bit_ffc() to the synopsis.
Document new APIs.
Document the initialization state of the bit strings
allocated/declared by bit_alloc() and bit_decl().
Correct documentation for bitstr_size(). The original code comments
indicate the size is in bytes, not "elements of bitstr_t". The new
implementation follows this lead. Only hastd assumed "elements"
rather than bytes and it has been corrected.
etc/mtree/BSD.tests.dist:
tests/sys/Makefile:
tests/sys/sys/Makefile:
tests/sys/sys/bitstring.c:
Add tests for all existing and new functionality.
include/bitstring.h
Include all headers needed by sys/bitstring.h
lib/libbluetooth/bluetooth.h:
usr.sbin/bluetooth/hccontrol/le.c:
Include bitstring.h instead of sys/bitstring.h.
sbin/hastd/activemap.c:
Correct usage of bitstr_size().
sys/dev/xen/blkback/blkback.c
Use new bit_alloc.
sys/kern/subr_unit.c:
Remove hard-coded assumption that sizeof(bitstr_t) is 1. Get rid of
unrb.busy, which caches the number of bits set in unrb.map. When
INVARIANTS are disabled, nothing needs to know that information.
callapse_unr can be adapted to use bit_ffs and bit_ffc instead.
Eliminating unrb.busy saves memory, simplifies the code, and
provides a slight speedup when INVARIANTS are disabled.
sys/net/flowtable.c:
Use the new kernel implementation of bit-alloc, instead of hacking
the old libc-dependent macro.
sys/sys/param.h
Update __FreeBSD_version to indicate availability of new API
Submitted by: gibbs, asomers
Reviewed by: gibbs, ngie
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D6004
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|---|---|---|
| .. | ||
| BSD.debug.dist | ||
| BSD.groff.dist | ||
| BSD.include.dist | ||
| BSD.lib32.dist | ||
| BSD.libsoft.dist | ||
| BSD.release.dist | ||
| BSD.root.dist | ||
| BSD.sendmail.dist | ||
| BSD.tests.dist | ||
| BSD.usr.dist | ||
| BSD.var.dist | ||
| Makefile | ||
| README | ||
$FreeBSD$
Note: If you modify these files, please keep hier(7) updated!
These files are used to create empty file hierarchies for building the
system into. Some notes about working with them are placed here to try
and keep them in good working order.
a) The files use 4 space indentation, and other than in the header
comments, should not contain any tabs. An indentation of 4 is
preferable to the standard indentation of 8 because the indentation
of levels in these files can become quite deep causing the line to
overflow 80 characters.
This also matches with the files generated when using the
mtree -c option, which was implemented that way for the same reason.
b) Only directories should be listed here.
c) The listing should be kept in filename sorted order.
d) Sanity checking changes to these files can be done by following
this procedure (the sed -e is ugly, but fixing mtree -c to
not emit the trailing white space would be even uglier):
mkdir /tmp/MTREE
mtree -deU -f BSD.X.dist -p /tmp/MTREE
mtree -cdin -k uname,gname,mode -p /tmp/MTREE | \
sed -e 's/ *$//' >BSD.X.new
diff -u BSD.X.dist BSD.X.new
rm -r /tmp/MTREE
Note that you will get some differences about /set lines,
and uname= gname= on certain directory areas, mainly man page
sections. This is caused by mtree not having a look ahead
mechanism for making better selections for these as it
traverses the hierarchy.
The BSD.X.new file should NOT be committed, as it will be missing
the correct header, and important keywords like ``nochange''.
Simply use the diff for a sanity check to make sure things are in
the correct order and correctly indented.
e) Further sanity checking of the system builds with DESTDIR=/someplace
are more complicated, but can often catch missing entries in these
files. I tend to run this more complete sanity check shortly after
the target date for a new release is announced.
If you want details on it bug me about it via email to
rgrimes@FreeBSD.org.