Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
BITSTRING(3)	       FreeBSD Library Functions Manual		  BITSTRING(3)

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

SYNOPSIS
     #include <bitstring.h>

     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 suffi-
     cient 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	num-
     bered 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 refer-
     enced 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 <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
     The bitstring functions first appeared in 4.4BSD.

FreeBSD	10.1			 July 19, 1993			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | HISTORY

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=bitstring&sektion=3&manpath=FreeBSD+7.1-RELEASE>

home | help