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 #define BITSET_FOREACH_SET(__i, __tmp, __set, __size) \
 133    for (__tmp = *(__set), __i = 0; \
 134         (__i = __bitset_next_set(__i, &__tmp, __set, __size)) < __size;)
 135
 136 #ifdef __cplusplus
 137
 138 /**
 139  * Simple C++ wrapper of a bitset type of static size, with value semantics
 140  * and basic bitwise arithmetic operators.  The operators defined below are
 141  * expected to have the same semantics as the same operator applied to other
 142  * fundamental integer types.  T is the name of the struct to instantiate
 143  * it as, and N is the number of bits in the bitset.
 144  */
 145 #define DECLARE_BITSET_T(T, N) struct T {                       \
 146       EXPLICIT_CONVERSION                                       \
 147       operator bool() const                                     \
 148       {                                                         \
 149          for (unsigned i = 0; i < BITSET_WORDS(N); i++)         \
 150             if (words[i])                                       \
 151                return true;                                     \
 152          return false;                                          \
 153       }                                                         \
 154                                                                 \
 155       T &                                                       \
 156       operator=(int x)                                          \
 157       {                                                         \
 158          const T c = {{ (BITSET_WORD)x }};                      \
 159          return *this = c;                                      \
 160       }                                                         \
 161                                                                 \
 162       friend bool                                               \
 163       operator==(const T &b, const T &c)                        \
 164       {                                                         \
 165          return BITSET_EQUAL(b.words, c.words);                 \
 166       }                                                         \
 167                                                                 \
 168       friend bool                                               \
 169       operator!=(const T &b, const T &c)                        \
 170       {                                                         \
 171          return !(b == c);                                      \
 172       }                                                         \
 173                                                                 \
 174       friend bool                                               \
 175       operator==(const T &b, int x)                             \
 176       {                                                         \
 177          const T c = {{ (BITSET_WORD)x }};                      \
 178          return b == c;                                         \
 179       }                                                         \
 180                                                                 \
 181       friend bool                                               \
 182       operator!=(const T &b, int x)                             \
 183       {                                                         \
 184          return !(b == x);                                      \
 185       }                                                         \
 186                                                                 \
 187       friend T                                                  \
 188       operator~(const T &b)                                     \
 189       {                                                         \
 190          T c;                                                   \
 191          for (unsigned i = 0; i < BITSET_WORDS(N); i++)         \
 192             c.words[i] = ~b.words[i];                           \
 193          return c;                                              \
 194       }                                                         \
 195                                                                 \
 196       T &                                                       \
 197       operator|=(const T &b)                                    \
 198       {                                                         \
 199          for (unsigned i = 0; i < BITSET_WORDS(N); i++)         \
 200             words[i] |= b.words[i];                             \
 201          return *this;                                          \
 202       }                                                         \
 203                                                                 \
 204       friend T                                                  \
 205       operator|(const T &b, const T &c)                         \
 206       {                                                         \
 207          T d = b;                                               \
 208          d |= c;                                                \
 209          return d;                                              \
 210       }                                                         \
 211                                                                 \
 212       T &                                                       \
 213       operator&=(const T &b)                                    \
 214       {                                                         \
 215          for (unsigned i = 0; i < BITSET_WORDS(N); i++)         \
 216             words[i] &= b.words[i];                             \
 217          return *this;                                          \
 218       }                                                         \
 219                                                                 \
 220       friend T                                                  \
 221       operator&(const T &b, const T &c)                         \
 222       {                                                         \
 223          T d = b;                                               \
 224          d &= c;                                                \
 225          return d;                                              \
 226       }                                                         \
 227                                                                 \
 228       bool                                                      \
 229       test(unsigned i) const                                    \
 230       {                                                         \
 231          return BITSET_TEST(words, i);                          \
 232       }                                                         \
 233                                                                 \
 234       T &                                                       \
 235       set(unsigned i)                                           \
 236       {                                                         \
 237          BITSET_SET(words, i);                                  \
 238          return *this;                                          \
 239       }                                                         \
 240                                                                 \
 241       T &                                                       \
 242       clear(unsigned i)                                         \
 243       {                                                         \
 244          BITSET_CLEAR(words, i);                                \
 245          return *this;                                          \
 246       }                                                         \
 247                                                                 \
 248       BITSET_WORD words[BITSET_WORDS(N)];                       \
 249    }
 250
 251 #endif
 252
 253 #endif