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1.1 root 1: .\" Copyright (c) 1989 The Regents of the University of California.
2: .\" All rights reserved.
3: .\"
4: .\" This code is derived from software contributed to Berkeley by
5: .\" Paul Vixie.
6: .\"
7: .\" Redistribution and use in source and binary forms are permitted provided
8: .\" that: (1) source distributions retain this entire copyright notice and
9: .\" comment, and (2) distributions including binaries display the following
10: .\" acknowledgement: ``This product includes software developed by the
11: .\" University of California, Berkeley and its contributors'' in the
12: .\" documentation or other materials provided with the distribution and in
13: .\" all advertising materials mentioning features or use of this software.
14: .\" Neither the name of the University nor the names of its contributors may
15: .\" be used to endorse or promote products derived from this software without
16: .\" specific prior written permission.
17: .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18: .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19: .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20: .\"
21: .\" @(#)bitstring.3 5.3 (Berkeley) 6/23/90
22: .\"
23: .TH BITSTRING 3 "June 23, 1990"
24: .UC 4
25: .SH NAME
26: bit_alloc, bit_clear, bit_decl, bit_ffs, bit_nclear, bit_nset,
27: bit_set, bitstr_size, bit_test \- bit-string manipulation macros
28: .SH SYNOPSIS
29: .ft B
30: .nf
31: #include <bitstring.h>
32:
33: name = bit_alloc(nbits)
34: bitstr_t *name;
35: int nbits;
36:
37: bit_decl(name, nbits)
38: bitstr_t name;
39: int nbits;
40:
41: bit_clear(name, bit)
42: bitstr_t name;
43: int bit;
44:
45: bit_ffc(name, nbits, value)
46: bitstr_t name;
47: int nbits, *value;
48:
49: bit_ffs(name, nbits, value)
50: bitstr_t name;
51: int nbits, *value;
52:
53: bit_nclear(name, start, stop)
54: bitstr_t name;
55: int start, stop;
56:
57: bit_nset(name, start, stop)
58: bitstr_t name;
59: int start, stop;
60:
61: bit_set(name, bit)
62: bitstr_t name;
63: int bit;
64:
65: bitstr_size(nbits)
66: int nbits;
67:
68: bit_test(name, bit)
69: bitstr_t name;
70: int bit;
71: .fi
72: .ft R
73: .SH DESCRIPTION
74: These macros operate on strings of bits.
75: .PP
76: .I Bit_alloc
77: returns a pointer of type
78: .I bitstr_t\ *
79: to sufficient space to store
80: .I nbits
81: bits, or NULL if no space is available.
82: .PP
83: .I Bit_decl
84: is a macro for allocating sufficient space to store
85: .I nbits
86: bits on the stack.
87: .PP
88: .I Bitstr_size
89: returns the number of elements of type
90: .I bitstr_t
91: necessary to store
92: .I nbits
93: bits.
94: This is useful for copying bit strings.
95: .PP
96: .I Bit_clear
97: and
98: .I bit_set
99: clear or set the zero-based numbered bit
100: .IR bit ,
101: in the bit string
102: .IR name .
103: .PP
104: .I Bit_nset
105: and
106: .I bit_nclear
107: set or clear the zero-based numbered bits from
108: .I start
109: to
110: .I stop
111: in the bit string
112: .IR name .
113: .PP
114: .I Bit_test
115: evaluates to zero if the zero-based numbered bit
116: .I bit
117: of bit string
118: .I name
119: is set, and non-zero otherwise.
120: .PP
121: .I Bit_ffs
122: stores in the location referenced by
123: .I value
124: the zero-based number of the first bit set in the array of
125: .I nbits
126: bits referenced by
127: .IR name .
128: If no bits are set, the location referenced by
129: .I value
130: is set to -1.
131: .PP
132: .I Bit_ffc
133: stores in the location referenced by
134: .I value
135: the zero-based number of the first bit not set in the array of
136: .I nbits
137: bits referenced by
138: .IR name .
139: If all bits are set, the location referenced by
140: .I value
141: is set to -1.
142: .PP
143: The arguments to these macros are evaluated only once and may safely
144: have side effects.
145: .SH EXAMPLE
146: .nf
147: .in +5
148: #include <limits.h>
149: #include <bitstring.h>
150:
151: ...
152: #define LPR_BUSY_BIT 0
153: #define LPR_FORMAT_BIT 1
154: #define LPR_DOWNLOAD_BIT 2
155: ...
156: #define LPR_AVAILABLE_BIT 9
157: #define LPR_MAX_BITS 10
158:
159: make_lpr_available()
160: {
161: bitstr_t bit_decl(bitlist, LPR_MAX_BITS);
162: ...
163: bit_nclear(bitlist, 0, LPR_MAX_BITS - 1);
164: ...
165: if (!bit_test(bitlist, LPR_BUSY_BIT)) {
166: bit_clear(bitlist, LPR_FORMAT_BIT);
167: bit_clear(bitlist, LPR_DOWNLOAD_BIT);
168: bit_set(bitlist, LPR_AVAILABLE_BIT);
169: }
170: }
171: .fi
172: .SH "SEE ALSO"
173: malloc(3)
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