src/util/bitset.h

   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/bitscan.h"
  35 #include "util/macros.h"
  36
  37 /****************************************************************************
  38  * generic bitset implementation
  39  */
  40
  41 #define BITSET_WORD unsigned int
  42 #define BITSET_WORDBITS (sizeof (BITSET_WORD) * 8)
  43
  44 /* bitset declarations
  45  */
  46 #define BITSET_WORDS(bits) (((bits) + BITSET_WORDBITS - 1) / BITSET_WORDBITS)
  47 #define BITSET_DECLARE(name, bits) BITSET_WORD name[BITSET_WORDS(bits)]
  48
  49 /* bitset operations
  50  */
  51 #define BITSET_COPY(x, y) memcpy( (x), (y), sizeof (x) )
  52 #define BITSET_EQUAL(x, y) (memcmp( (x), (y), sizeof (x) ) == 0)
  53 #define BITSET_ZERO(x) memset( (x), 0, sizeof (x) )
  54 #define BITSET_ONES(x) memset( (x), 0xff, sizeof (x) )
  55
  56 #define BITSET_BITWORD(b) ((b) / BITSET_WORDBITS)
  57 #define BITSET_BIT(b) (1u << ((b) % BITSET_WORDBITS))
  58
  59 /* single bit operations
  60  */
  61 #define BITSET_TEST(x, b) (((x)[BITSET_BITWORD(b)] & BITSET_BIT(b)) != 0)
  62 #define BITSET_SET(x, b) ((x)[BITSET_BITWORD(b)] |= BITSET_BIT(b))
  63 #define BITSET_CLEAR(x, b) ((x)[BITSET_BITWORD(b)] &= ~BITSET_BIT(b))
  64
  65 #define BITSET_MASK(b) (((b) % BITSET_WORDBITS == 0) ? ~0 : BITSET_BIT(b) - 1)
  66 #define BITSET_RANGE(b, e) ((BITSET_MASK((e) + 1)) & ~(BITSET_BIT(b) - 1))
  67
  68 /* bit range operations
  69  */
  70 #define BITSET_TEST_RANGE(x, b, e) \
  71    (BITSET_BITWORD(b) == BITSET_BITWORD(e) ? \
  72    (((x)[BITSET_BITWORD(b)] & BITSET_RANGE(b, e)) != 0) : \
  73    (assert (!"BITSET_TEST_RANGE: bit range crosses word boundary"), 0))
  74 #define BITSET_SET_RANGE(x, b, e) \
  75    (BITSET_BITWORD(b) == BITSET_BITWORD(e) ? \
  76    ((x)[BITSET_BITWORD(b)] |= BITSET_RANGE(b, e)) : \
  77    (assert (!"BITSET_SET_RANGE: bit range crosses word boundary"), 0))
  78 #define BITSET_CLEAR_RANGE(x, b, e) \
  79    (BITSET_BITWORD(b) == BITSET_BITWORD(e) ? \
  80    ((x)[BITSET_BITWORD(b)] &= ~BITSET_RANGE(b, e)) : \
  81    (assert (!"BITSET_CLEAR_RANGE: bit range crosses word boundary"), 0))
  82
  83 /* Get first bit set in a bitset.
  84  */
  85 static inline int
  86 __bitset_ffs(const BITSET_WORD *x, int n)
  87 {
  88    int i;
  89
  90    for (i = 0; i < n; i++) {
  91       if (x[i])
  92          return ffs(x[i]) + BITSET_WORDBITS * i;
  93    }
  94
  95    return 0;
  96 }
  97
  98 #define BITSET_FFS(x) __bitset_ffs(x, ARRAY_SIZE(x))
  99
 100 static inline unsigned
 101 __bitset_next_set(unsigned i, BITSET_WORD *tmp,
 102                   const BITSET_WORD *set, unsigned size)
 103 {
 104    unsigned bit, word;
 105
 106    /* NOTE: The initial conditions for this function are very specific.  At
 107     * the start of the loop, the tmp variable must be set to *set and the
 108     * initial i value set to 0.  This way, if there is a bit set in the first
 109     * word, we ignore the i-value and just grab that bit (so 0 is ok, even
 110     * though 0 may be returned).  If the first word is 0, then the value of
 111     * `word` will be 0 and we will go on to look at the second word.
 112     */
 113    word = BITSET_BITWORD(i);
 114    while (*tmp == 0) {
 115       word++;
 116
 117       if (word >= BITSET_WORDS(size))
 118          return size;
 119
 120       *tmp = set[word];
 121    }
 122
 123    /* Find the next set bit in the non-zero word */
 124    bit = ffs(*tmp) - 1;
 125
 126    /* Unset the bit */
 127    *tmp &= ~(1ull << bit);
 128
 129    return word * BITSET_WORDBITS + bit;
 130 }
 131
 132 /**
 133  * Iterates over each set bit in a set
 134  *
 135  * @param __i    iteration variable, bit number
 136  * @param __set  the bitset to iterate (will not be modified)
 137  * @param __size number of bits in the set to consider
 138  */
 139 #define BITSET_FOREACH_SET(__i, __set, __size) \
 140    for (BITSET_WORD __tmp = *(__set), *__foo = &__tmp; __foo != NULL; __foo = NULL) \
 141       for (__i = 0; \
 142            (__i = __bitset_next_set(__i, &__tmp, __set, __size)) < __size;)
 143
 144 #ifdef __cplusplus
 145
 146 /**
 147  * Simple C++ wrapper of a bitset type of static size, with value semantics
 148  * and basic bitwise arithmetic operators.  The operators defined below are
 149  * expected to have the same semantics as the same operator applied to other
 150  * fundamental integer types.  T is the name of the struct to instantiate
 151  * it as, and N is the number of bits in the bitset.
 152  */
 153 #define DECLARE_BITSET_T(T, N) struct T {                       \
 154       EXPLICIT_CONVERSION                                       \
 155       operator bool() const                                     \
 156       {                                                         \
 157          for (unsigned i = 0; i < BITSET_WORDS(N); i++)         \
 158             if (words[i])                                       \
 159                return true;                                     \
 160          return false;                                          \
 161       }                                                         \
 162                                                                 \
 163       T &                                                       \
 164       operator=(int x)                                          \
 165       {                                                         \
 166          const T c = {{ (BITSET_WORD)x }};                      \
 167          return *this = c;                                      \
 168       }                                                         \
 169                                                                 \
 170       friend bool                                               \
 171       operator==(const T &b, const T &c)                        \
 172       {                                                         \
 173          return BITSET_EQUAL(b.words, c.words);                 \
 174       }                                                         \
 175                                                                 \
 176       friend bool                                               \
 177       operator!=(const T &b, const T &c)                        \
 178       {                                                         \
 179          return !(b == c);                                      \
 180       }                                                         \
 181                                                                 \
 182       friend bool                                               \
 183       operator==(const T &b, int x)                             \
 184       {                                                         \
 185          const T c = {{ (BITSET_WORD)x }};                      \
 186          return b == c;                                         \
 187       }                                                         \
 188                                                                 \
 189       friend bool                                               \
 190       operator!=(const T &b, int x)                             \
 191       {                                                         \
 192          return !(b == x);                                      \
 193       }                                                         \
 194                                                                 \
 195       friend T                                                  \
 196       operator~(const T &b)                                     \
 197       {                                                         \
 198          T c;                                                   \
 199          for (unsigned i = 0; i < BITSET_WORDS(N); i++)         \
 200             c.words[i] = ~b.words[i];                           \
 201          return c;                                              \
 202       }                                                         \
 203                                                                 \
 204       T &                                                       \
 205       operator|=(const T &b)                                    \
 206       {                                                         \
 207          for (unsigned i = 0; i < BITSET_WORDS(N); i++)         \
 208             words[i] |= b.words[i];                             \
 209          return *this;                                          \
 210       }                                                         \
 211                                                                 \
 212       friend T                                                  \
 213       operator|(const T &b, const T &c)                         \
 214       {                                                         \
 215          T d = b;                                               \
 216          d |= c;                                                \
 217          return d;                                              \
 218       }                                                         \
 219                                                                 \
 220       T &                                                       \
 221       operator&=(const T &b)                                    \
 222       {                                                         \
 223          for (unsigned i = 0; i < BITSET_WORDS(N); i++)         \
 224             words[i] &= b.words[i];                             \
 225          return *this;                                          \
 226       }                                                         \
 227                                                                 \
 228       friend T                                                  \
 229       operator&(const T &b, const T &c)                         \
 230       {                                                         \
 231          T d = b;                                               \
 232          d &= c;                                                \
 233          return d;                                              \
 234       }                                                         \
 235                                                                 \
 236       bool                                                      \
 237       test(unsigned i) const                                    \
 238       {                                                         \
 239          return BITSET_TEST(words, i);                          \
 240       }                                                         \
 241                                                                 \
 242       T &                                                       \
 243       set(unsigned i)                                           \
 244       {                                                         \
 245          BITSET_SET(words, i);                                  \
 246          return *this;                                          \
 247       }                                                         \
 248                                                                 \
 249       T &                                                       \
 250       clear(unsigned i)                                         \
 251       {                                                         \
 252          BITSET_CLEAR(words, i);                                \
 253          return *this;                                          \
 254       }                                                         \
 255                                                                 \
 256       BITSET_WORD words[BITSET_WORDS(N)];                       \
 257    }
 258
 259 #endif
 260
 261 #endif