NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

     #include <bitstring.h>

     bitstr_t *
     bit_alloc(int nbits);

     bit_clear(bit_str name, int bit);

     bit_decl(bit_str name, int nbits);

     bit_ffc(bit_str name, int nbits, int *value);

     bit_ffs(bit_str name, int nbits, int *value);

     bit_nclear(bit_str name, int start, int stop);

     bit_nset(bit_str name, int start, int stop);

     bit_set(bit_str name, int bit);

     bitstr_size(int nbits);

     bit_test(bit_str name, int bit);

DESCRIPTION    [Toc]    [Back]

     These macros operate on strings of bits.

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

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

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

     The  bit_clear() and bit_set() macros clear or set the zerobased numbered
     bit bit, in the bit string name.

     The bit_nclear() and bit_nset() macros clear or set 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 zerobased
 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  bit_ffc()  macro  stores  in the location referenced by
value the zerobased
 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    [Toc]    [Back]

           #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    [Toc]    [Back]

     malloc(3)

HISTORY    [Toc]    [Back]

     The bitstring functions first appeared in 4.4BSD.

OpenBSD      3.6                           July      19,     1993