NAME
bitset(9) — BITSET_DEFINE, BITSET_T_INITIALIZER, BITSET_FSET, BIT_CLR, BIT_COPY, BIT_ISSET, BIT_SET, BIT_ZERO, BIT_FILL, BIT_SETOF, BIT_EMPTY, BIT_ISFULLSET, BIT_FFS, BIT_FLS, BIT_COUNT, BIT_SUBSET, BIT_OVERLAP, BIT_CMP, BIT_OR, BIT_OR2, BIT_AND, BIT_AND2, BIT_NAND, BIT_NAND2, BIT_XOR, BIT_XOR2, BIT_CLR_ATOMIC, BIT_SET_ATOMIC, BIT_SET_ATOMIC_ACQ, BIT_AND_ATOMIC, BIT_OR_ATOMIC, BIT_COPY_STORE_REL — bitset manipulation macrosSYNOPSIS
#include <sys/_bitset.h>#include <sys/bitset.h> BITSET_DEFINE(STRUCTNAME, const SETSIZE); BITSET_T_INITIALIZER(ARRAY_CONTENTS); BITSET_FSET(N_WORDS); BIT_CLR(const SETSIZE, size_t bit, struct STRUCTNAME *bitset); BIT_COPY(const SETSIZE, struct STRUCTNAME *from, struct STRUCTNAME *to); bool
BIT_ISSET(const SETSIZE, size_t bit, struct STRUCTNAME *bitset); BIT_SET(const SETSIZE, size_t bit, struct STRUCTNAME *bitset); BIT_ZERO(const SETSIZE, struct STRUCTNAME *bitset); BIT_FILL(const SETSIZE, struct STRUCTNAME *bitset); BIT_SETOF(const SETSIZE, size_t bit, struct STRUCTNAME *bitset); bool
BIT_EMPTY(const SETSIZE, struct STRUCTNAME *bitset); bool
BIT_ISFULLSET(const SETSIZE, struct STRUCTNAME *bitset); int
BIT_FFS(const SETSIZE, struct STRUCTNAME *bitset); int
BIT_FLS(const SETSIZE, struct STRUCTNAME *bitset); int
BIT_COUNT(const SETSIZE, struct STRUCTNAME *bitset); bool
BIT_SUBSET(const SETSIZE, struct STRUCTNAME *haystack, struct STRUCTNAME *needle); bool
BIT_OVERLAP(const SETSIZE, struct STRUCTNAME *bitset1, struct STRUCTNAME *bitset2); bool
BIT_CMP(const SETSIZE, struct STRUCTNAME *bitset1, struct STRUCTNAME *bitset2); BIT_OR(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src); BIT_OR2(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src1, struct STRUCTNAME *src2); BIT_AND(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src); BIT_AND2(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src1, struct STRUCTNAME *src2); BIT_NAND(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src); BIT_NAND2(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src1, struct STRUCTNAME *src2); BIT_XOR(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src); BIT_XOR2(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src1, struct STRUCTNAME *src2); BIT_CLR_ATOMIC(const SETSIZE, size_t bit, struct STRUCTNAME *bitset); BIT_SET_ATOMIC(const SETSIZE, size_t bit, struct STRUCTNAME *bitset); BIT_SET_ATOMIC_ACQ(const SETSIZE, size_t bit, struct STRUCTNAME *bitset); BIT_AND_ATOMIC(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src); BIT_OR_ATOMIC(const SETSIZE, struct STRUCTNAME *dst, struct STRUCTNAME *src); BIT_COPY_STORE_REL(const SETSIZE, struct STRUCTNAME *from, struct STRUCTNAME *to);
DESCRIPTION
The bitset(9) family of macros provide a flexible and efficient bitset implementation if the maximum size of the set is known at compilation. Throughout this manual page, the name SETSIZE refers to the size of the bitset in bits. Individual bits in bitsets are referenced with indices zero through SETSIZE - 1. One example use of <sys/bitset.h> is <sys/cpuset.h>. The BITSET_DEFINE() macro defines a bitset struct STRUCTNAME with room to represent SETSIZE bits. The BITSET_T_INITIALIZER() macro allows one to initialize a bitset struct with a compile time literal value. The BITSET_FSET() macro generates a compile time literal, usable by BITSET_T_INITIALIZER(), representing a full bitset (all bits set). For examples of BITSET_T_INITIALIZER() and BITSET_FSET() usage, see the BITSET_T_INITIALIZER EXAMPLE section. The N_WORDS parameter to BITSET_FSET() should be:__bitset_words(SETSIZE)
true
if
bitset is empty.
The BIT_ISFULLSET() macro returns
true
if
bitset is full (all bits set).
The BIT_FFS() macro returns the 1-index of the
first (lowest) set bit in bitset, or zero if
bitset is empty. Like with
ffs(3), to use the non-zero result of
BIT_FFS() as a
bit index parameter to any other
bitset(9) macro, you must subtract one from the
result.
The BIT_FLS() macro returns the 1-index of the last
(highest) set bit in bitset, or zero if
bitset is empty. Like with
fls(3), to use the non-zero result of
BIT_FLS() as a
bit index parameter to any other
bitset(9) macro, you must subtract one from the
result.
The BIT_COUNT() macro returns the total number of
set bits in bitset.
The BIT_SUBSET() macro returns
true
if
needle is a subset of
haystack.
The BIT_OVERLAP() macro returns
true
if
bitset1 and
bitset2 have any common bits. (That is, if
bitset1 AND
bitset2 is not the empty set.)
The BIT_CMP() macro returns
true
if
bitset1 is NOT equal to
bitset2.
The BIT_OR() macro sets bits present in
src in dst.
(It is the bitset(9) equivalent of the scalar:
dst |= src.)
BIT_OR_ATOMIC() is similar, but sets bits in the
component machine words in dst atomically.
(That is, if dst is composed of multiple
machine words, BIT_OR_ATOMIC() performs multiple
individually atomic operations.)
The BIT_OR2() macro computes
src1 bitwise or
src2 and assigns the result to
dst. (It is the
bitset(9) equivalent of the scalar:
dst = src1 |
src2.)
The BIT_AND() macro clears bits absent from
src from
dst. (It is the
bitset(9) equivalent of the scalar:
dst &=
src.)
BIT_AND_ATOMIC() is similar, with the same atomic
semantics as BIT_OR_ATOMIC().
The BIT_AND2() macro computes
src1 bitwise and
src2 and assigns the result to
dst. (It is the
bitset(9) equivalent of the scalar:
dst = src1
& src2.)
The BIT_NAND() macro clears bits set in
src from
dst. (It is the
bitset(9) equivalent of the scalar:
dst &= ~
src.)
The BIT_NAND2() macro computes
src1 bitwise and not
src2 and assigns the result to
dst. (It is the
bitset(9) equivalent of the scalar:
dst = src1
& ~ src2.)
The BIT_XOR() macro toggles bits set in
src in dst.
(It is the bitset(9) equivalent of the scalar:
dst ^= src.)
The BIT_XOR2() macro computes
src1 bitwise exclusive or
src2 and assigns the result to
dst. (It is the
bitset(9) equivalent of the scalar:
dst = src1 ^
src2.)
BITSET_T_INITIALIZER EXAMPLE
BITSET_DEFINE(_myset, MYSETSIZE); struct _myset myset; /* Initialize myset to filled (all bits set) */ myset = BITSET_T_INITIALIZER(BITSET_FSET(__bitset_words(MYSETSIZE))); /* Initialize myset to only the lowest bit set */ myset = BITSET_T_INITIALIZER(0x1);
SEE ALSO
bitstring(3), cpuset(9)HISTORY
The bitset(9) macros first appeared in FreeBSD 10.0 in January 2014. They were MFCed to FreeBSD 9.3, released in July 2014. This manual page first appeared in FreeBSD 11.0.AUTHORS
The bitset(9) macros were generalized and pulled out of <sys/cpuset.h> as <sys/_bitset.h> and <sys/bitset.h> by Attilio Rao <[email protected]>. This manual page was written by Conrad Meyer <[email protected]>.CAVEATS
The SETSIZE argument to all of these macros must match the value given to BITSET_DEFINE(). Unlike every other reference to individual set members, which are zero-indexed, BIT_FFS() and BIT_FLS() return a one-indexed result (or zero if the set is empty).July 7, 2017 | Debian |