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/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
  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
 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