lib/bitmap.h

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef BITMAP_H
  18 #define BITMAP_H 1
  19
  20 #include <limits.h>
  21 #include <stdlib.h>
  22 #include "util.h"
  23
  24 static inline unsigned long *
  25 bitmap_unit__(const unsigned long *bitmap, size_t offset)
  26 {
  27     return CONST_CAST(unsigned long *, &bitmap[offset / BITMAP_ULONG_BITS]);
  28 }
  29
  30 static inline unsigned long
  31 bitmap_bit__(size_t offset)
  32 {
  33     return 1UL << (offset % BITMAP_ULONG_BITS);
  34 }
  35
  36 static inline size_t
  37 bitmap_n_longs(size_t n_bits)
  38 {
  39     return BITMAP_N_LONGS(n_bits);
  40 }
  41
  42 static inline size_t
  43 bitmap_n_bytes(size_t n_bits)
  44 {
  45     return bitmap_n_longs(n_bits) * sizeof(unsigned long int);
  46 }
  47
  48 static inline unsigned long *
  49 bitmap_allocate(size_t n_bits)
  50 {
  51     return xzalloc(bitmap_n_bytes(n_bits));
  52 }
  53
  54 /* Initializes bitmap to all-1-bits and returns the bitmap pointer. */
  55 static inline unsigned long *
  56 bitmap_init1(unsigned long *bitmap, size_t n_bits)
  57 {
  58     size_t n_longs = bitmap_n_longs(n_bits);
  59     size_t n_bytes = bitmap_n_bytes(n_bits);
  60     size_t r_bits = n_bits % BITMAP_ULONG_BITS;
  61
  62     memset(bitmap, 0xff, n_bytes);
  63     if (r_bits) {
  64         bitmap[n_longs - 1] = (1UL << r_bits) - 1;
  65     }
  66     return bitmap;
  67 }
  68
  69 /* Allocates and returns a bitmap initialized to all-1-bits. */
  70 static inline unsigned long *
  71 bitmap_allocate1(size_t n_bits)
  72 {
  73     return bitmap_init1(xmalloc(bitmap_n_bytes(n_bits)), n_bits);
  74 }
  75
  76 static inline unsigned long *
  77 bitmap_clone(const unsigned long *bitmap, size_t n_bits)
  78 {
  79     return xmemdup(bitmap, bitmap_n_bytes(n_bits));
  80 }
  81
  82 static inline void
  83 bitmap_free(unsigned long *bitmap)
  84 {
  85     free(bitmap);
  86 }
  87
  88 static inline bool
  89 bitmap_is_set(const unsigned long *bitmap, size_t offset)
  90 {
  91     return (*bitmap_unit__(bitmap, offset) & bitmap_bit__(offset)) != 0;
  92 }
  93
  94 static inline unsigned long *
  95 bitmap_set1(unsigned long *bitmap, size_t offset)
  96 {
  97     *bitmap_unit__(bitmap, offset) |= bitmap_bit__(offset);
  98     return bitmap;
  99 }
 100
 101 static inline unsigned long *
 102 bitmap_set0(unsigned long *bitmap, size_t offset)
 103 {
 104     *bitmap_unit__(bitmap, offset) &= ~bitmap_bit__(offset);
 105     return bitmap;
 106 }
 107
 108 static inline unsigned long *
 109 bitmap_set(unsigned long *bitmap, size_t offset, bool value)
 110 {
 111     return (value) ? bitmap_set1(bitmap, offset) : bitmap_set0(bitmap, offset);
 112 }
 113
 114 /* Sets 'n' bits of a single unit. */
 115 static inline void
 116 bitmap_set_n__(unsigned long *bitmap, size_t start, size_t n, bool value)
 117 {
 118     unsigned long mask = ((1UL << n) - 1) << start % BITMAP_ULONG_BITS;
 119
 120     if (value) {
 121         *bitmap_unit__(bitmap, start) |= mask;
 122     } else {
 123         *bitmap_unit__(bitmap, start) &= ~mask;
 124     }
 125 }
 126
 127 /* Sets 'count' consecutive bits in 'bitmap', starting at bit offset 'start',
 128  * to 'value'. */
 129 static inline unsigned long *
 130 bitmap_set_multiple(unsigned long *bitmap, size_t start, size_t count,
 131                     bool value)
 132 {
 133     if (count && start % BITMAP_ULONG_BITS) {
 134         size_t n = MIN(count, BITMAP_ULONG_BITS - start % BITMAP_ULONG_BITS);
 135
 136         bitmap_set_n__(bitmap, start, n, value);
 137         count -= n;
 138         start += n;
 139     }
 140     for (; count >= BITMAP_ULONG_BITS; count -= BITMAP_ULONG_BITS) {
 141         *bitmap_unit__(bitmap, start) = (unsigned long)!value - 1;
 142         start += BITMAP_ULONG_BITS;
 143     }
 144     if (count) {
 145         bitmap_set_n__(bitmap, start, count, value);
 146     }
 147     return bitmap;
 148 }
 149
 150 /* Returns the number of 1-bits in the 'n'-bit bitmap at 'bitmap'. */
 151 static inline size_t
 152 bitmap_count1(const unsigned long int *bitmap, size_t n)
 153 {
 154     size_t i;
 155     size_t count = 0;
 156
 157     BUILD_ASSERT(ULONG_MAX <= UINT64_MAX);
 158     for (i = 0; i < BITMAP_N_LONGS(n); i++) {
 159         count += count_1bits(bitmap[i]);
 160     }
 161     return count;
 162 }
 163
 164 /* "dst &= arg;" for n-bit dst and arg.  */
 165 static inline unsigned long *
 166 bitmap_and(unsigned long *dst, const unsigned long *arg, size_t n)
 167 {
 168     size_t i;
 169
 170     for (i = 0; i < BITMAP_N_LONGS(n); i++) {
 171         dst[i] &= arg[i];
 172     }
 173     return dst;
 174 }
 175
 176 /* "dst |= arg;" for n-bit dst and arg.  */
 177 static inline unsigned long *
 178 bitmap_or(unsigned long *dst, const unsigned long *arg, size_t n)
 179 {
 180     size_t i;
 181
 182     for (i = 0; i < BITMAP_N_LONGS(n); i++) {
 183         dst[i] |= arg[i];
 184     }
 185     return dst;
 186 }
 187
 188 /* "dst = ~dst;" for n-bit dst.  */
 189 static inline unsigned long *
 190 bitmap_not(unsigned long *dst, size_t n)
 191 {
 192     size_t i;
 193
 194     for (i = 0; i < n / BITMAP_ULONG_BITS; i++) {
 195         dst[i] = ~dst[i];
 196     }
 197     if (n % BITMAP_ULONG_BITS) {
 198         dst[i] ^= (1UL << (n % BITMAP_ULONG_BITS)) - 1;
 199     }
 200     return dst;
 201 }
 202
 203 /* Compares the 'n' bits in bitmaps 'a' and 'b'.  Returns true if all bits are
 204  * equal, false otherwise. */
 205 static inline bool
 206 bitmap_equal(const unsigned long *a, const unsigned long *b, size_t n)
 207 {
 208     if (memcmp(a, b, n / BITMAP_ULONG_BITS * sizeof(unsigned long))) {
 209         return false;
 210     }
 211     if (n % BITMAP_ULONG_BITS) {
 212         unsigned long mask = (1UL << n % BITMAP_ULONG_BITS) - 1;
 213         unsigned long diff = *bitmap_unit__(a, n) ^ *bitmap_unit__(b, n);
 214
 215         return !(diff & mask);
 216     }
 217     return true;
 218 }
 219
 220 /* Scans 'bitmap' from bit offset 'start' to 'end', excluding 'end' itself.
 221  * Returns the bit offset of the lowest-numbered bit set to 'target', or 'end'
 222  * if all of the bits are set to '!target'.  'target' is typically a
 223  * compile-time constant, so it makes sense to inline this.  Compiler may also
 224  * optimize parts away depending on the 'start' and 'end' values passed in. */
 225 static inline size_t
 226 bitmap_scan(const unsigned long *bitmap, bool target, size_t start, size_t end)
 227 {
 228     if (OVS_LIKELY(start < end)) {
 229         unsigned long *p, unit;
 230
 231         p = bitmap_unit__(bitmap, start);
 232         unit = (target ? *p : ~*p) >> (start % BITMAP_ULONG_BITS);
 233         if (!unit) {
 234             start -= start % BITMAP_ULONG_BITS; /* Round down. */
 235             start += BITMAP_ULONG_BITS; /* Start of the next unit. */
 236
 237             for (; start < end; start += BITMAP_ULONG_BITS) {
 238                 unit = target ? *++p : ~*++p;
 239                 if (unit) {
 240                     goto found;
 241                 }
 242             }
 243             return end;
 244         }
 245 found:
 246         start += raw_ctz(unit);  /* unit != 0 */
 247         if (OVS_LIKELY(start < end)) {
 248             return start;
 249         }
 250     }
 251     return end;
 252 }
 253
 254 /* Returns true if the 1-bits in 'super' are a superset of the 1-bits in 'sub',
 255  * false otherwise.  'super' and 'sub' both have 'n_bits' bits. */
 256 static inline bool
 257 bitmap_is_superset(const unsigned long int *super,
 258                    const unsigned long int *sub, size_t n_bits)
 259 {
 260     size_t n_longs = bitmap_n_longs(n_bits);
 261     for (size_t i = 0; i < n_longs; i++) {
 262         if (!uint_is_superset(super[i], sub[i])) {
 263             return false;
 264         }
 265     }
 266     return true;
 267 }
 268
 269 /* Returns true if all of the 'n' bits in 'bitmap' are 0,
 270  * false if at least one bit is a 1.*/
 271 static inline bool
 272 bitmap_is_all_zeros(const unsigned long *bitmap, size_t n)
 273 {
 274     return bitmap_scan(bitmap, true, 0, n) == n;
 275 }
 276
 277 #define BITMAP_FOR_EACH_1_RANGE(IDX, BEGIN, END, BITMAP)           \
 278     for ((IDX) = bitmap_scan(BITMAP, true, BEGIN, END); (IDX) < (END);   \
 279          (IDX) = bitmap_scan(BITMAP, true, (IDX) + 1, END))
 280 #define BITMAP_FOR_EACH_1(IDX, SIZE, BITMAP)        \
 281     BITMAP_FOR_EACH_1_RANGE(IDX, 0, SIZE, BITMAP)
 282
 283 /* More efficient access to a map of single ullong. */
 284 #define ULLONG_FOR_EACH_1(IDX, MAP)                 \
 285     for (uint64_t map__ = (MAP);                    \
 286          map__ && (((IDX) = raw_ctz(map__)), true); \
 287          map__ = zero_rightmost_1bit(map__))
 288
 289 #define ULLONG_SET0(MAP, OFFSET) ((MAP) &= ~(1ULL << (OFFSET)))
 290 #define ULLONG_SET1(MAP, OFFSET) ((MAP) |= 1ULL << (OFFSET))
 291
 292 /* Returns the value of a bit in a map as a bool. */
 293 #define ULLONG_GET(MAP, OFFSET) !!((MAP) & (1ULL << (OFFSET)))
 294
 295 #endif /* bitmap.h */