bitstring(3) 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>
name = bit_alloc(nbits)
bitstr_t *name;
int nbits;
bit_decl(name, nbits)
bitstr_t name;
int nbits;
bit_clear(name, bit)
bitstr_t name;
int bit;
bit_ffc(name, nbits, value)
bitstr_t name;
int nbits, *value;
bit_ffs(name, nbits, value)
bitstr_t name;
int nbits, *value;
bit_nclear(name, start, stop)
bitstr_t name;
int start, stop;
bit_nset(name, start, stop)
bitstr_t name;
int start, stop;
bit_set(name, bit)
bitstr_t name;
int bit;
bitstr_size(nbits)
int nbits;
bit_test(name, bit)
bitstr_t name;
int bit;
DESCRIPTION
These macros operate on strings of bits.
Bit_alloc returns a pointer of type bitstr_t * to sufficient space to
store nbits bits, or NULL if no space is available.
Bit_decl is a macro for allocating sufficient space to store nbits bits
on the stack.
Bitstr_size returns the number of elements of type bitstr_t necessary
to store nbits bits. This is useful for copying bit strings.
Bit_clear and bit_set clear or set the zero-based numbered bit bit, in
the bit string name.
Bit_nset and bit_nclear set or clear the zero-based numbered bits from
start to stop in the bit string name.
Bit_test evaluates to zero if the zero-based numbered bit bit of bit
string name is set, and non-zero otherwise.
Bit_ffs sets *value to the zero-based number of the first bit set in
the array of nbits bits referenced by name. If no bits are set, *value
is set to -1.
Bit_ffc sets *value to the zero-based number of the first bit not set
in the array of nbits bits referenced by name. If all bits are set,
value is set to -1.
EXAMPLE
#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)
4th Berkeley Distribution December 13, 1989 bitstring(3)
fcron 3.2.1 - Generated Mon Sep 11 10:30:26 CDT 2017