BITSTRING(3bsd) 3bsd BITSTRING(3bsd)

bit_alloc, bit_clear, bit_decl, bit_ffs, bit_nclear, bit_nset, bit_set, bitstr_size, bit_testbit-string manipulation macros

library “libbsd”

#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);

These macros operate on strings of bits.

The macro () returns a pointer of type “bitstr_t *” to sufficient space to store nbits bits, or NULL if no space is available.

The macro () allocates sufficient space to store nbits bits on the stack.

The macro () returns the number of elements of type bitstr_t necessary to store nbits bits. This is useful for copying bit strings.

The macros () and () clear or set the zero-based numbered bit bit, in the bit string name.

The () and () macros set or clear the zero-based numbered bits from start through stop in the bit string name.

The () macro evaluates to non-zero if the zero-based numbered bit bit of bit string name is set, and zero otherwise.

The () 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 () 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 <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);
	}
}

malloc(3)

The bitstring functions first appeared in 4.4BSD.

July 19, 1993 Linux 5.15.13-arch1-1