| BITSTRING(3) | Library Functions Manual | BITSTRING(3) |
bit_alloc, bit_clear,
bit_decl, bit_ffc,
bit_ffs, bit_nclear,
bit_nset, bit_set,
bitstr_size, bit_test —
#include <sys/types.h>
#include <bitstring.h>
bitstr_t *
bit_decl(bitstr_t
*name, size_t
nbits);
bitstr_t *
bit_alloc(size_t
nbits);
bit_clear(bitstr_t
*name, size_t
bit);
bit_ffc(const
bitstr_t *name, size_t
nbits, int
*value);
bit_ffs(const
bitstr_t *name, size_t
nbits, int
*value);
bit_nclear(bitstr_t
*name, size_t
start, size_t
stop);
bit_nset(bitstr_t
*name, size_t
start, size_t
stop);
bit_set(bitstr_t
*name, size_t
bit);
bitstr_size(size_t
nbits);
bit_test(const
bitstr_t *name, size_t
bit);
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 to 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.
#include <limits.h>
#include <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
void
make_lpr_available(void)
{
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);
}
}
bitstring functions first appeared in
4.4BSD.
| December 29, 2016 | NetBSD 9.3 |