Manpages

NAME

bit_alloc, bit_clear, bit_decl, bit_ffs, bit_nclear, bit_nset, bit_set, bitstr_size, bit_test — bit-string manipulation macros

LIBRARY

Utility functions from BSD systems (libbsd, -lbsd)

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>

...

...

make_lpr_available()
{

}

SEE ALSO

malloc(3)

HISTORY

The bitstring functions first appeared in 4.4BSD.

BSD July 19, 1993 BSD