include/qemu/bitops.h

   1 /*
   2  * Bitops Module
   3  *
   4  * Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
   5  *
   6  * Mostly inspired by (stolen from) linux/bitmap.h and linux/bitops.h
   7  *
   8  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
   9  * See the COPYING.LIB file in the top-level directory.
  10  */
  11
  12 #ifndef BITOPS_H
  13 #define BITOPS_H
  14
  15
  16 #include "host-utils.h"
  17 #include "atomic.h"
  18
  19 #define BITS_PER_BYTE           CHAR_BIT
  20 #define BITS_PER_LONG           (sizeof (unsigned long) * BITS_PER_BYTE)
  21
  22 #define BIT(nr)                 (1UL << (nr))
  23 #define BIT_MASK(nr)            (1UL << ((nr) % BITS_PER_LONG))
  24 #define BIT_WORD(nr)            ((nr) / BITS_PER_LONG)
  25 #define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
  26
  27 /**
  28  * set_bit - Set a bit in memory
  29  * @nr: the bit to set
  30  * @addr: the address to start counting from
  31  */
  32 static inline void set_bit(long nr, unsigned long *addr)
  33 {
  34     unsigned long mask = BIT_MASK(nr);
  35     unsigned long *p = addr + BIT_WORD(nr);
  36
  37     *p  |= mask;
  38 }
  39
  40 /**
  41  * set_bit_atomic - Set a bit in memory atomically
  42  * @nr: the bit to set
  43  * @addr: the address to start counting from
  44  */
  45 static inline void set_bit_atomic(long nr, unsigned long *addr)
  46 {
  47     unsigned long mask = BIT_MASK(nr);
  48     unsigned long *p = addr + BIT_WORD(nr);
  49
  50     atomic_or(p, mask);
  51 }
  52
  53 /**
  54  * clear_bit - Clears a bit in memory
  55  * @nr: Bit to clear
  56  * @addr: Address to start counting from
  57  */
  58 static inline void clear_bit(long nr, unsigned long *addr)
  59 {
  60     unsigned long mask = BIT_MASK(nr);
  61     unsigned long *p = addr + BIT_WORD(nr);
  62
  63     *p &= ~mask;
  64 }
  65
  66 /**
  67  * change_bit - Toggle a bit in memory
  68  * @nr: Bit to change
  69  * @addr: Address to start counting from
  70  */
  71 static inline void change_bit(long nr, unsigned long *addr)
  72 {
  73     unsigned long mask = BIT_MASK(nr);
  74     unsigned long *p = addr + BIT_WORD(nr);
  75
  76     *p ^= mask;
  77 }
  78
  79 /**
  80  * test_and_set_bit - Set a bit and return its old value
  81  * @nr: Bit to set
  82  * @addr: Address to count from
  83  */
  84 static inline int test_and_set_bit(long nr, unsigned long *addr)
  85 {
  86     unsigned long mask = BIT_MASK(nr);
  87     unsigned long *p = addr + BIT_WORD(nr);
  88     unsigned long old = *p;
  89
  90     *p = old | mask;
  91     return (old & mask) != 0;
  92 }
  93
  94 /**
  95  * test_and_clear_bit - Clear a bit and return its old value
  96  * @nr: Bit to clear
  97  * @addr: Address to count from
  98  */
  99 static inline int test_and_clear_bit(long nr, unsigned long *addr)
 100 {
 101     unsigned long mask = BIT_MASK(nr);
 102     unsigned long *p = addr + BIT_WORD(nr);
 103     unsigned long old = *p;
 104
 105     *p = old & ~mask;
 106     return (old & mask) != 0;
 107 }
 108
 109 /**
 110  * test_and_change_bit - Change a bit and return its old value
 111  * @nr: Bit to change
 112  * @addr: Address to count from
 113  */
 114 static inline int test_and_change_bit(long nr, unsigned long *addr)
 115 {
 116     unsigned long mask = BIT_MASK(nr);
 117     unsigned long *p = addr + BIT_WORD(nr);
 118     unsigned long old = *p;
 119
 120     *p = old ^ mask;
 121     return (old & mask) != 0;
 122 }
 123
 124 /**
 125  * test_bit - Determine whether a bit is set
 126  * @nr: bit number to test
 127  * @addr: Address to start counting from
 128  */
 129 static inline int test_bit(long nr, const unsigned long *addr)
 130 {
 131     return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
 132 }
 133
 134 /**
 135  * find_last_bit - find the last set bit in a memory region
 136  * @addr: The address to start the search at
 137  * @size: The maximum size to search
 138  *
 139  * Returns the bit number of the first set bit, or size.
 140  */
 141 unsigned long find_last_bit(const unsigned long *addr,
 142                             unsigned long size);
 143
 144 /**
 145  * find_next_bit - find the next set bit in a memory region
 146  * @addr: The address to base the search on
 147  * @offset: The bitnumber to start searching at
 148  * @size: The bitmap size in bits
 149  */
 150 unsigned long find_next_bit(const unsigned long *addr,
 151                             unsigned long size,
 152                             unsigned long offset);
 153
 154 /**
 155  * find_next_zero_bit - find the next cleared bit in a memory region
 156  * @addr: The address to base the search on
 157  * @offset: The bitnumber to start searching at
 158  * @size: The bitmap size in bits
 159  */
 160
 161 unsigned long find_next_zero_bit(const unsigned long *addr,
 162                                  unsigned long size,
 163                                  unsigned long offset);
 164
 165 /**
 166  * find_first_bit - find the first set bit in a memory region
 167  * @addr: The address to start the search at
 168  * @size: The maximum size to search
 169  *
 170  * Returns the bit number of the first set bit.
 171  */
 172 static inline unsigned long find_first_bit(const unsigned long *addr,
 173                                            unsigned long size)
 174 {
 175     unsigned long result, tmp;
 176
 177     for (result = 0; result < size; result += BITS_PER_LONG) {
 178         tmp = *addr++;
 179         if (tmp) {
 180             result += ctzl(tmp);
 181             return result < size ? result : size;
 182         }
 183     }
 184     /* Not found */
 185     return size;
 186 }
 187
 188 /**
 189  * find_first_zero_bit - find the first cleared bit in a memory region
 190  * @addr: The address to start the search at
 191  * @size: The maximum size to search
 192  *
 193  * Returns the bit number of the first cleared bit.
 194  */
 195 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
 196                                                 unsigned long size)
 197 {
 198     return find_next_zero_bit(addr, size, 0);
 199 }
 200
 201 static inline unsigned long hweight_long(unsigned long w)
 202 {
 203     unsigned long count;
 204
 205     for (count = 0; w; w >>= 1) {
 206         count += w & 1;
 207     }
 208     return count;
 209 }
 210
 211 /**
 212  * rol8 - rotate an 8-bit value left
 213  * @word: value to rotate
 214  * @shift: bits to roll
 215  */
 216 static inline uint8_t rol8(uint8_t word, unsigned int shift)
 217 {
 218     return (word << shift) | (word >> (8 - shift));
 219 }
 220
 221 /**
 222  * ror8 - rotate an 8-bit value right
 223  * @word: value to rotate
 224  * @shift: bits to roll
 225  */
 226 static inline uint8_t ror8(uint8_t word, unsigned int shift)
 227 {
 228     return (word >> shift) | (word << (8 - shift));
 229 }
 230
 231 /**
 232  * rol16 - rotate a 16-bit value left
 233  * @word: value to rotate
 234  * @shift: bits to roll
 235  */
 236 static inline uint16_t rol16(uint16_t word, unsigned int shift)
 237 {
 238     return (word << shift) | (word >> (16 - shift));
 239 }
 240
 241 /**
 242  * ror16 - rotate a 16-bit value right
 243  * @word: value to rotate
 244  * @shift: bits to roll
 245  */
 246 static inline uint16_t ror16(uint16_t word, unsigned int shift)
 247 {
 248     return (word >> shift) | (word << (16 - shift));
 249 }
 250
 251 /**
 252  * rol32 - rotate a 32-bit value left
 253  * @word: value to rotate
 254  * @shift: bits to roll
 255  */
 256 static inline uint32_t rol32(uint32_t word, unsigned int shift)
 257 {
 258     return (word << shift) | (word >> (32 - shift));
 259 }
 260
 261 /**
 262  * ror32 - rotate a 32-bit value right
 263  * @word: value to rotate
 264  * @shift: bits to roll
 265  */
 266 static inline uint32_t ror32(uint32_t word, unsigned int shift)
 267 {
 268     return (word >> shift) | (word << (32 - shift));
 269 }
 270
 271 /**
 272  * rol64 - rotate a 64-bit value left
 273  * @word: value to rotate
 274  * @shift: bits to roll
 275  */
 276 static inline uint64_t rol64(uint64_t word, unsigned int shift)
 277 {
 278     return (word << shift) | (word >> (64 - shift));
 279 }
 280
 281 /**
 282  * ror64 - rotate a 64-bit value right
 283  * @word: value to rotate
 284  * @shift: bits to roll
 285  */
 286 static inline uint64_t ror64(uint64_t word, unsigned int shift)
 287 {
 288     return (word >> shift) | (word << (64 - shift));
 289 }
 290
 291 /**
 292  * extract32:
 293  * @value: the value to extract the bit field from
 294  * @start: the lowest bit in the bit field (numbered from 0)
 295  * @length: the length of the bit field
 296  *
 297  * Extract from the 32 bit input @value the bit field specified by the
 298  * @start and @length parameters, and return it. The bit field must
 299  * lie entirely within the 32 bit word. It is valid to request that
 300  * all 32 bits are returned (ie @length 32 and @start 0).
 301  *
 302  * Returns: the value of the bit field extracted from the input value.
 303  */
 304 static inline uint32_t extract32(uint32_t value, int start, int length)
 305 {
 306     assert(start >= 0 && length > 0 && length <= 32 - start);
 307     return (value >> start) & (~0U >> (32 - length));
 308 }
 309
 310 /**
 311  * extract64:
 312  * @value: the value to extract the bit field from
 313  * @start: the lowest bit in the bit field (numbered from 0)
 314  * @length: the length of the bit field
 315  *
 316  * Extract from the 64 bit input @value the bit field specified by the
 317  * @start and @length parameters, and return it. The bit field must
 318  * lie entirely within the 64 bit word. It is valid to request that
 319  * all 64 bits are returned (ie @length 64 and @start 0).
 320  *
 321  * Returns: the value of the bit field extracted from the input value.
 322  */
 323 static inline uint64_t extract64(uint64_t value, int start, int length)
 324 {
 325     assert(start >= 0 && length > 0 && length <= 64 - start);
 326     return (value >> start) & (~0ULL >> (64 - length));
 327 }
 328
 329 /**
 330  * sextract32:
 331  * @value: the value to extract the bit field from
 332  * @start: the lowest bit in the bit field (numbered from 0)
 333  * @length: the length of the bit field
 334  *
 335  * Extract from the 32 bit input @value the bit field specified by the
 336  * @start and @length parameters, and return it, sign extended to
 337  * an int32_t (ie with the most significant bit of the field propagated
 338  * to all the upper bits of the return value). The bit field must lie
 339  * entirely within the 32 bit word. It is valid to request that
 340  * all 32 bits are returned (ie @length 32 and @start 0).
 341  *
 342  * Returns: the sign extended value of the bit field extracted from the
 343  * input value.
 344  */
 345 static inline int32_t sextract32(uint32_t value, int start, int length)
 346 {
 347     assert(start >= 0 && length > 0 && length <= 32 - start);
 348     /* Note that this implementation relies on right shift of signed
 349      * integers being an arithmetic shift.
 350      */
 351     return ((int32_t)(value << (32 - length - start))) >> (32 - length);
 352 }
 353
 354 /**
 355  * sextract64:
 356  * @value: the value to extract the bit field from
 357  * @start: the lowest bit in the bit field (numbered from 0)
 358  * @length: the length of the bit field
 359  *
 360  * Extract from the 64 bit input @value the bit field specified by the
 361  * @start and @length parameters, and return it, sign extended to
 362  * an int64_t (ie with the most significant bit of the field propagated
 363  * to all the upper bits of the return value). The bit field must lie
 364  * entirely within the 64 bit word. It is valid to request that
 365  * all 64 bits are returned (ie @length 64 and @start 0).
 366  *
 367  * Returns: the sign extended value of the bit field extracted from the
 368  * input value.
 369  */
 370 static inline int64_t sextract64(uint64_t value, int start, int length)
 371 {
 372     assert(start >= 0 && length > 0 && length <= 64 - start);
 373     /* Note that this implementation relies on right shift of signed
 374      * integers being an arithmetic shift.
 375      */
 376     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
 377 }
 378
 379 /**
 380  * deposit32:
 381  * @value: initial value to insert bit field into
 382  * @start: the lowest bit in the bit field (numbered from 0)
 383  * @length: the length of the bit field
 384  * @fieldval: the value to insert into the bit field
 385  *
 386  * Deposit @fieldval into the 32 bit @value at the bit field specified
 387  * by the @start and @length parameters, and return the modified
 388  * @value. Bits of @value outside the bit field are not modified.
 389  * Bits of @fieldval above the least significant @length bits are
 390  * ignored. The bit field must lie entirely within the 32 bit word.
 391  * It is valid to request that all 32 bits are modified (ie @length
 392  * 32 and @start 0).
 393  *
 394  * Returns: the modified @value.
 395  */
 396 static inline uint32_t deposit32(uint32_t value, int start, int length,
 397                                  uint32_t fieldval)
 398 {
 399     uint32_t mask;
 400     assert(start >= 0 && length > 0 && length <= 32 - start);
 401     mask = (~0U >> (32 - length)) << start;
 402     return (value & ~mask) | ((fieldval << start) & mask);
 403 }
 404
 405 /**
 406  * deposit64:
 407  * @value: initial value to insert bit field into
 408  * @start: the lowest bit in the bit field (numbered from 0)
 409  * @length: the length of the bit field
 410  * @fieldval: the value to insert into the bit field
 411  *
 412  * Deposit @fieldval into the 64 bit @value at the bit field specified
 413  * by the @start and @length parameters, and return the modified
 414  * @value. Bits of @value outside the bit field are not modified.
 415  * Bits of @fieldval above the least significant @length bits are
 416  * ignored. The bit field must lie entirely within the 64 bit word.
 417  * It is valid to request that all 64 bits are modified (ie @length
 418  * 64 and @start 0).
 419  *
 420  * Returns: the modified @value.
 421  */
 422 static inline uint64_t deposit64(uint64_t value, int start, int length,
 423                                  uint64_t fieldval)
 424 {
 425     uint64_t mask;
 426     assert(start >= 0 && length > 0 && length <= 64 - start);
 427     mask = (~0ULL >> (64 - length)) << start;
 428     return (value & ~mask) | ((fieldval << start) & mask);
 429 }
 430
 431 #endif