Jack2: bitset.h Source File

Jack2 1.9.12

bitset.h
1 /*
2 * bitset.h -- some simple bit vector set operations.
3 *
4 * This is useful for sets of small non-negative integers. There are
5 * some obvious set operations that are not implemented because I
6 * don't need them right now.
7 *
8 * These functions represent sets as arrays of unsigned 32-bit
9 * integers allocated on the heap. The first entry contains the set
10 * cardinality (number of elements allowed), followed by one or more
11 * words containing bit vectors.
12 *
13 * $Id: bitset.h,v 1.2 2005/11/23 11:24:29 letz Exp $
14 */
15
16 /*
17 * Copyright (C) 2005 Jack O'Quin
18 *
19 * This program is free software; you can redistribute it and/or
20 * modify it under the terms of the GNU General Public License as
21 * published by the Free Software Foundation; either version 2 of the
22 * License, or (at your option) any later version.
23 *
24 * This program is distributed in the hope that it will be useful,
25 * but WITHOUT ANY WARRANTY; without even the implied warranty of
26 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
27 * General Public License for more details.
28 *
29 * You should have received a copy of the GNU General Public License
30 * along with this program; if not, write to the Free Software
31 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
32 */
33
34 #ifndef __bitset_h__
35 #define __bitset_h__
36
37 #include <inttypes.h> /* POSIX standard fixed-size types */
38 #include <assert.h> /* `#define NDEBUG' to disable */
39
40 /* On some 64-bit machines, this implementation may be slightly
41 * inefficient, depending on how compilers allocate space for
42 * uint32_t. For the set sizes I currently need, this is acceptable.
43 * It should not be hard to pack the bits better, if that becomes
44 * worthwhile.
45 */
46 typedef uint32_t _bitset_word_t;
47 typedef _bitset_word_t *bitset_t;
48
49 #define WORD_SIZE(cardinality) (1+((cardinality)+31)/32)
50 #define BYTE_SIZE(cardinality) (WORD_SIZE(cardinality)*sizeof(_bitset_word_t))
51 #define WORD_INDEX(element) (1+(element)/32)
52 #define BIT_INDEX(element) ((element)&037)
53
54 static inline void
55 bitset_add(bitset_t set
56 , unsigned int element)
57 {
58 assert(element < set
59 [0]);
60 set
61 [WORD_INDEX(element)] |= (1 << BIT_INDEX(element));
62 }
63
64 static inline void
65 bitset_copy(bitset_t to_set, bitset_t from_set)
66 {
67 assert(to_set[0] == from_set[0]);
68 memcpy(to_set, from_set, BYTE_SIZE(to_set[0]));
69 }
70
71 static inline void
72 bitset_create(bitset_t *set
73 , unsigned int cardinality)
74 {
75 *set
76 = (bitset_t) calloc(WORD_SIZE(cardinality),
77 sizeof(_bitset_word_t));
78 assert(*set
79 );
80 *set
81 [0] = cardinality;
82 }
83
84 static inline void
85 bitset_destroy(bitset_t *set
86 )
87 {
88 if (*set
89 ) {
90 free(*set
91 );
92 *set
93 = (bitset_t) 0;
94 }
95 }
96
97 static inline int
98 bitset_empty(bitset_t set
99 )
100 {
101 int i;
102 _bitset_word_t result = 0;
103 int nwords = WORD_SIZE(set
104 [0]);
105 for (i = 1; i < nwords; i++) {
106 result |= set
107 [i];
108 }
109 return (result == 0);
110 }
111
112 static inline int
113 bitset_contains(bitset_t set
114 , unsigned int element)
115 {
116 assert(element < set
117 [0]);
118 return (0 != (set
119 [WORD_INDEX(element)] & (1 << BIT_INDEX(element))));
120 }
121
122 static inline void
123 bitset_remove(bitset_t set
124 , unsigned int element)
125 {
126 assert(element < set
127 [0]);
128 set
129 [WORD_INDEX(element)] &= ~(1 << BIT_INDEX(element));
130 }
131
132 #endif /* __bitset_h__ */