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1 /*
2  * Mesa 3-D graphics library
3  *
4  * Copyright (C) 2006  Brian Paul   All Rights Reserved.
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a
7  * copy of this software and associated documentation files (the "Software"),
8  * to deal in the Software without restriction, including without limitation
9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10  * and/or sell copies of the Software, and to permit persons to whom the
11  * Software is furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included
14  * in all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
17  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
20  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22  * OTHER DEALINGS IN THE SOFTWARE.
23  */
24 
25 /**
26  * \file bitset.h
27  * \brief Bitset of arbitrary size definitions.
28  * \author Michal Krol
29  */
30 
31 #ifndef BITSET_H
32 #define BITSET_H
33 
34 #include "util/u_math.h"
35 
36 /****************************************************************************
37  * generic bitset implementation
38  */
39 
40 #define BITSET_WORD unsigned int
41 #define BITSET_WORDBITS (sizeof (BITSET_WORD) * 8)
42 
43 /* bitset declarations
44  */
45 #define BITSET_WORDS(bits) (((bits) + BITSET_WORDBITS - 1) / BITSET_WORDBITS)
46 #define BITSET_DECLARE(name, bits) BITSET_WORD name[BITSET_WORDS(bits)]
47 
48 /* bitset operations
49  */
50 #define BITSET_COPY(x, y) memcpy( (x), (y), sizeof (x) )
51 #define BITSET_EQUAL(x, y) (memcmp( (x), (y), sizeof (x) ) == 0)
52 #define BITSET_ZERO(x) memset( (x), 0, sizeof (x) )
53 #define BITSET_ONES(x) memset( (x), 0xff, sizeof (x) )
54 
55 #define BITSET_BITWORD(b) ((b) / BITSET_WORDBITS)
56 #define BITSET_BIT(b) (1 << ((b) % BITSET_WORDBITS))
57 
58 /* single bit operations
59  */
60 #define BITSET_TEST(x, b) ((x)[BITSET_BITWORD(b)] & BITSET_BIT(b))
61 #define BITSET_SET(x, b) ((x)[BITSET_BITWORD(b)] |= BITSET_BIT(b))
62 #define BITSET_CLEAR(x, b) ((x)[BITSET_BITWORD(b)] &= ~BITSET_BIT(b))
63 
64 #define BITSET_MASK(b) ((b) == BITSET_WORDBITS ? ~0 : BITSET_BIT(b) - 1)
65 #define BITSET_RANGE(b, e) (BITSET_MASK((e) + 1) & ~BITSET_MASK(b))
66 
67 /* bit range operations
68  */
69 #define BITSET_TEST_RANGE(x, b, e) \
70    (BITSET_BITWORD(b) == BITSET_BITWORD(e) ? \
71    ((x)[BITSET_BITWORD(b)] & BITSET_RANGE(b, e)) : \
72    (assert (!"BITSET_TEST_RANGE: bit range crosses word boundary"), 0))
73 #define BITSET_SET_RANGE(x, b, e) \
74    (BITSET_BITWORD(b) == BITSET_BITWORD(e) ? \
75    ((x)[BITSET_BITWORD(b)] |= BITSET_RANGE(b, e)) : \
76    (assert (!"BITSET_SET_RANGE: bit range crosses word boundary"), 0))
77 #define BITSET_CLEAR_RANGE(x, b, e) \
78    (BITSET_BITWORD(b) == BITSET_BITWORD(e) ? \
79    ((x)[BITSET_BITWORD(b)] &= ~BITSET_RANGE(b, e)) : \
80    (assert (!"BITSET_CLEAR_RANGE: bit range crosses word boundary"), 0))
81 
82 /* Get first bit set in a bitset.
83  */
84 static inline int
__bitset_ffs(const BITSET_WORD * x,int n)85 __bitset_ffs(const BITSET_WORD *x, int n)
86 {
87    int i;
88 
89    for (i = 0; i < n; i++) {
90       if (x[i])
91 	 return ffs(x[i]) + BITSET_WORDBITS * i;
92    }
93 
94    return 0;
95 }
96 
97 #define BITSET_FFS(x) __bitset_ffs(x, ARRAY_SIZE(x))
98 
99 static inline unsigned
__bitset_next_set(unsigned i,BITSET_WORD * tmp,const BITSET_WORD * set,unsigned size)100 __bitset_next_set(unsigned i, BITSET_WORD *tmp,
101                   const BITSET_WORD *set, unsigned size)
102 {
103    unsigned bit, word;
104 
105    /* NOTE: The initial conditions for this function are very specific.  At
106     * the start of the loop, the tmp variable must be set to *set and the
107     * initial i value set to 0.  This way, if there is a bit set in the first
108     * word, we ignore the i-value and just grab that bit (so 0 is ok, even
109     * though 0 may be returned).  If the first word is 0, then the value of
110     * `word` will be 0 and we will go on to look at the second word.
111     */
112    word = BITSET_BITWORD(i);
113    while (*tmp == 0) {
114       word++;
115 
116       if (word >= BITSET_WORDS(size))
117          return size;
118 
119       *tmp = set[word];
120    }
121 
122    /* Find the next set bit in the non-zero word */
123    bit = ffs(*tmp) - 1;
124 
125    /* Unset the bit */
126    *tmp &= ~(1ull << bit);
127 
128    return word * BITSET_WORDBITS + bit;
129 }
130 
131 #define BITSET_FOREACH_SET(__i, __tmp, __set, __size) \
132    for (__tmp = *(__set), __i = 0; \
133         (__i = __bitset_next_set(__i, &__tmp, __set, __size)) < __size;)
134 
135 #endif
136