BITSTRING(3bsd) | 3bsd | BITSTRING(3bsd) |
NAME¶
bit_alloc
, bit_clear
,
bit_decl
, bit_ffs
,
bit_nclear
, bit_nset
,
bit_set
, bitstr_size
,
bit_test
—
SYNOPSIS¶
#include <bitstring.h>
(See
libbsd(7) for include usage.)
bitstr_t *
bit_alloc
(int
nbits);
void
bit_decl
(bitstr_t
*name, int
nbits);
void
bit_clear
(bitstr_t
*name, int
bit);
void
bit_ffc
(bitstr_t
*name, int nbits,
int *value);
void
bit_ffs
(bitstr_t
*name, int nbits,
int *value);
void
bit_nclear
(bitstr_t
*name, int start,
int stop);
void
bit_nset
(bitstr_t
*name, int start,
int stop);
void
bit_set
(bitstr_t
*name, int
bit);
int
bitstr_size
(int
nbits);
int
bit_test
(bitstr_t
*name, int
bit);
DESCRIPTION¶
These macros operate on strings of bits.The macro bit_alloc
() returns a pointer of
type “bitstr_t *” to sufficient space to
store nbits bits, or NULL
if
no space is available.
The macro bit_decl
() allocates sufficient
space to store nbits bits on the stack.
The macro bitstr_size
() returns the number
of elements of type bitstr_t necessary to store
nbits bits. This is useful for copying bit
strings.
The macros bit_clear
() and
bit_set
() clear or set the zero-based numbered bit
bit, in the bit string name.
The bit_nset
() and
bit_nclear
() macros set or clear the zero-based
numbered bits from start through
stop in the bit string name.
The bit_test
() macro evaluates to non-zero
if the zero-based numbered bit bit of bit string
name is set, and zero otherwise.
The bit_ffs
() macro stores in the location
referenced by value the zero-based number of the first
bit set in the array of nbits bits referenced by
name. If no bits are set, the location referenced by
value is set to -1.
The macro bit_ffc
() stores in the location
referenced by value the zero-based number of the first
bit not set in the array of nbits bits referenced by
name. If all bits are set, the location referenced by
value is set to -1.
The arguments to these macros are evaluated only once and may safely have side effects.
EXAMPLES¶
#include <limits.h> #include <bsd/bitstring.h> ... #define LPR_BUSY_BIT 0 #define LPR_FORMAT_BIT 1 #define LPR_DOWNLOAD_BIT 2 ... #define LPR_AVAILABLE_BIT 9 #define LPR_MAX_BITS 10 make_lpr_available() { bitstr_t bit_decl(bitlist, LPR_MAX_BITS); ... bit_nclear(bitlist, 0, LPR_MAX_BITS - 1); ... if (!bit_test(bitlist, LPR_BUSY_BIT)) { bit_clear(bitlist, LPR_FORMAT_BIT); bit_clear(bitlist, LPR_DOWNLOAD_BIT); bit_set(bitlist, LPR_AVAILABLE_BIT); } }
SEE ALSO¶
malloc(3)HISTORY¶
Thebitstring
functions first appeared in
4.4BSD.
July 19, 1993 | Linux 4.19.0-10-amd64 |