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BIT_ALLOC(3) Library Functions Manual BIT_ALLOC(3)

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

#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);

These macros operate on strings of bits.

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

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

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

The () and () macros clear or set the zero-based numbered bit bit, in the bit string name.

The () and () macros clear or set the zero-based numbered bits from start to stop in the bit string name.

The () macro evaluates to non-zero if the zero-based numbered bit bit of bit string name is set, and zero otherwise.

The () 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 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.

#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);
	}
}

malloc(3)

These functions first appeared in 4.4BSD.

August 30, 2019 OpenBSD-current