bit_alloc, bit_clear, bit_decl, bit_ffs, bit_nclear, bit_nset, bit_set, bitstr_size, bit_test − bit-string manipulation macros
#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;
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.
#include
<limits.h>
#include <bitstring.h>
#define |
|||||||
LPR_BUSY_BIT |
|||||||
0 | |||||||
#define |
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LPR_FORMAT_BIT |
|||||||
1 | |||||||
#define |
|||||||
LPR_DOWNLOAD_BIT |
2 | ||||||
#define |
|||||||
LPR_AVAILABLE_BIT |
9 | ||||||
#define |
|||||||
LPR_MAX_BITS |
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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)