1BITSTRING(3bsd) LOCAL BITSTRING(3bsd)
2
4 bit_alloc, bit_clear, bit_decl, bit_ffs, bit_nclear, bit_nset, bit_set,
5 bitstr_size, bit_test — bit-string manipulation macros
6
8 #include <bitstring.h>
9 (See libbsd(7) for include usage.)
10
11 bitstr_t *
12 bit_alloc(int nbits);
13
14 void
15 bit_decl(bitstr_t *name, int nbits);
16
17 void
18 bit_clear(bitstr_t *name, int bit);
19
20 void
21 bit_ffc(bitstr_t *name, int nbits, int *value);
22
23 void
24 bit_ffs(bitstr_t *name, int nbits, int *value);
25
26 void
27 bit_nclear(bitstr_t *name, int start, int stop);
28
29 void
30 bit_nset(bitstr_t *name, int start, int stop);
31
32 void
33 bit_set(bitstr_t *name, int bit);
34
35 int
36 bitstr_size(int nbits);
37
38 int
39 bit_test(bitstr_t *name, int bit);
40
42 These macros operate on strings of bits.
43
44 The macro bit_alloc() returns a pointer of type “bitstr_t *” to suffi‐
45 cient space to store nbits bits, or NULL if no space is available.
46
47 The macro bit_decl() allocates sufficient space to store nbits bits on
48 the stack.
49
50 The macro bitstr_size() returns the number of elements of type bitstr_t
51 necessary to store nbits bits. This is useful for copying bit strings.
52
53 The macros bit_clear() and bit_set() clear or set the zero-based numbered
54 bit bit, in the bit string name.
55
56 The bit_nset() and bit_nclear() macros set or clear the zero-based num‐
57 bered bits from start through stop in the bit string name.
58
59 The bit_test() macro evaluates to non-zero if the zero-based numbered bit
60 bit of bit string name is set, and zero otherwise.
61
62 The bit_ffs() macro stores in the location referenced by value the zero-
63 based number of the first bit set in the array of nbits bits referenced
64 by name. If no bits are set, the location referenced by value is set to
65 -1.
66
67 The macro bit_ffc() stores in the location referenced by value the zero-
68 based number of the first bit not set in the array of nbits bits refer‐
69 enced by name. If all bits are set, the location referenced by value is
70 set to -1.
71
72 The arguments to these macros are evaluated only once and may safely have
73 side effects.
74
76 #include <limits.h>
77 #include <bsd/bitstring.h>
78
79 ...
80 #define LPR_BUSY_BIT 0
81 #define LPR_FORMAT_BIT 1
82 #define LPR_DOWNLOAD_BIT 2
83 ...
84 #define LPR_AVAILABLE_BIT 9
85 #define LPR_MAX_BITS 10
86
87 make_lpr_available()
88 {
89 bitstr_t bit_decl(bitlist, LPR_MAX_BITS);
90 ...
91 bit_nclear(bitlist, 0, LPR_MAX_BITS - 1);
92 ...
93 if (!bit_test(bitlist, LPR_BUSY_BIT)) {
94 bit_clear(bitlist, LPR_FORMAT_BIT);
95 bit_clear(bitlist, LPR_DOWNLOAD_BIT);
96 bit_set(bitlist, LPR_AVAILABLE_BIT);
97 }
98 }
99
101 malloc(3)
102
104 The bitstring functions first appeared in 4.4BSD.
105
106BSD July 19, 1993 BSD