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58 .\" @(#)bitstring.3 8.1 (Berkeley) 7/19/93
78 .Nd bit-string manipulation functions and macros
82 .Fn bit_alloc "int nbits"
84 .Fn bit_decl "bitstr_t *name" "int nbits"
86 .Fn bit_clear "bitstr_t *name" "int bit"
88 .Fn bit_count "bitstr_t *name" "int count" "int nbits" "int *value"
90 .Fn bit_ffc "bitstr_t *name" "int nbits" "int *value"
92 .Fn bit_ffs "bitstr_t *name" "int nbits" "int *value"
94 .Fn bit_ffc_at "bitstr_t *name" "int start" "int nbits" "int *value"
96 .Fn bit_ffs_at "bitstr_t *name" "int start" "int nbits" "int *value"
98 .Fn bit_nclear "bitstr_t *name" "int start" "int stop"
100 .Fn bit_nset "bitstr_t *name" "int start" "int stop"
102 .Fn bit_set "bitstr_t *name" "int bit"
104 .Fn bitstr_size "int nbits"
106 .Fn bit_test "bitstr_t *name" "int bit"
108 These macros operate on strings of bits.
112 returns a pointer of type
114 to sufficient space to store
118 if no space is available.
119 If successful, the returned bit string is initialized with all bits cleared.
123 declares a bit string with sufficient space to store
127 may be used to include statically sized bit strings in structure
128 definitions or to create bit strings on the stack.
129 Users of this macro are responsible for initialization of the bit string,
130 typically via a global initialization of the containing struct or use of the
138 returns the number of bytes necessary to store
141 This is useful for copying bit strings.
147 clear or set the zero-based numbered bit
157 set or clear the zero-based numbered bits from
167 evaluates to non-zero if the zero-based numbered bit
171 is set, and zero otherwise.
175 stores in the location referenced by
177 the zero-based number of the first bit not set in the array of
181 If all bits are set, the location referenced by
188 stores in the location referenced by
190 the zero-based number of the first bit set in the array of
194 If no bits are set, the location referenced by
200 stores in the location referenced by
202 the zero-based number of the first bit not set in the array of
206 at or after the zero-based bit index
208 If all bits at or after
210 are set, the location referenced by
217 stores in the location referenced by
219 the zero-based number of the first bit set in the array of
223 at or after the zero-based bit index
225 If no bits are set after
227 the location referenced by
233 function stores in the location referenced by
235 the number of bits set in the array of
239 at or after the zero-based bit index
242 The arguments in bit string macros are evaluated only once and may safely
245 .Bd -literal -offset indent
247 #include <bitstring.h>
250 #define LPR_BUSY_BIT 0
251 #define LPR_FORMAT_BIT 1
252 #define LPR_DOWNLOAD_BIT 2
254 #define LPR_AVAILABLE_BIT 9
255 #define LPR_MAX_BITS 10
259 bitstr_t bit_decl(bitlist, LPR_MAX_BITS);
261 bit_nclear(bitlist, 0, LPR_MAX_BITS - 1);
263 if (!bit_test(bitlist, LPR_BUSY_BIT)) {
264 bit_clear(bitlist, LPR_FORMAT_BIT);
265 bit_clear(bitlist, LPR_DOWNLOAD_BIT);
266 bit_set(bitlist, LPR_AVAILABLE_BIT);
276 functions first appeared in