bitstring.3bsd man page
bit_alloc, bit_clear, bit_decl, bit_ffs, bit_nclear, bit_nset, bit_set, bitstr_size, bit_test — bit-string manipulation macros #include < void void void void void void void int int These macros operate on strings of bits. The macro The macro The macro The macros The The The The macro The arguments to these macros are evaluated only once and may safely have side effects. The bitstring functions first appeared in 4.4BSD. The man pages bit_alloc.3bsd(3), bit_clear.3bsd(3), bit_decl.3bsd(3), bit_ffc.3bsd(3), bit_ffs.3bsd(3), bit_nclear.3bsd(3), bit_nset.3bsd(3), bit_set.3bsd(3), bitstr_size.3bsd(3) and bit_test.3bsd(3) are aliases of bitstring.3bsd(3).Synopsis
bitstring.h
> (See libbsd(7) for include usage.)
bitstr_t *
bit_alloc
(int nbits);
bit_decl
(bitstr_t *name, int nbits);
bit_clear
(bitstr_t *name, int bit);
bit_ffc
(bitstr_t *name, int nbits, int *value);
bit_ffs
(bitstr_t *name, int nbits, int *value);
bit_nclear
(bitstr_t *name, int start, int stop);
bit_nset
(bitstr_t *name, int start, int stop);
bit_set
(bitstr_t *name, int bit);
bitstr_size
(int nbits);
bit_test
(bitstr_t *name, int bit); Description
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
() allocates 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
() macros set or clear the zero-based numbered bits from start through stop in the bit string name. bit_test
() macro evaluates to non-zero if the zero-based numbered bit bit of bit string name is set, and zero otherwise. 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. 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. Examples
#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);
}
}
See Also
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Referenced By