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 #include <stdint.h>
  16 #include <assert.h>
  17
  18 #include "host-utils.h"
  19 #include "atomic.h"
  20
  21 #define BITS_PER_BYTE           CHAR_BIT
  22 #define BITS_PER_LONG           (sizeof (unsigned long) * BITS_PER_BYTE)
  23
  24 #define BIT(nr)                 (1UL << (nr))
  25 #define BIT_MASK(nr)            (1UL << ((nr) % BITS_PER_LONG))
  26 #define BIT_WORD(nr)            ((nr) / BITS_PER_LONG)
  27 #define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
  28
  29 /**
  30  * set_bit - Set a bit in memory
  31  * @nr: the bit to set
  32  * @addr: the address to start counting from
  33  */
  34 static inline void set_bit(long nr, unsigned long *addr)
  35 {
  36     unsigned long mask = BIT_MASK(nr);
  37     unsigned long *p = addr + BIT_WORD(nr);
  38
  39     *p  |= mask;
  40 }
  41
  42 /**
  43  * set_bit_atomic - Set a bit in memory atomically
  44  * @nr: the bit to set
  45  * @addr: the address to start counting from
  46  */
  47 static inline void set_bit_atomic(long nr, unsigned long *addr)
  48 {
  49     unsigned long mask = BIT_MASK(nr);
  50     unsigned long *p = addr + BIT_WORD(nr);
  51
  52     atomic_or(p, mask);
  53 }
  54
  55 /**
  56  * clear_bit - Clears a bit in memory
  57  * @nr: Bit to clear
  58  * @addr: Address to start counting from
  59  */
  60 static inline void clear_bit(long nr, unsigned long *addr)
  61 {
  62     unsigned long mask = BIT_MASK(nr);
  63     unsigned long *p = addr + BIT_WORD(nr);
  64
  65     *p &= ~mask;
  66 }
  67
  68 /**
  69  * change_bit - Toggle a bit in memory
  70  * @nr: Bit to change
  71  * @addr: Address to start counting from
  72  */
  73 static inline void change_bit(long nr, unsigned long *addr)
  74 {
  75     unsigned long mask = BIT_MASK(nr);
  76     unsigned long *p = addr + BIT_WORD(nr);
  77
  78     *p ^= mask;
  79 }
  80
  81 /**
  82  * test_and_set_bit - Set a bit and return its old value
  83  * @nr: Bit to set
  84  * @addr: Address to count from
  85  */
  86 static inline int test_and_set_bit(long nr, unsigned long *addr)
  87 {
  88     unsigned long mask = BIT_MASK(nr);
  89     unsigned long *p = addr + BIT_WORD(nr);
  90     unsigned long old = *p;
  91
  92     *p = old | mask;
  93     return (old & mask) != 0;
  94 }
  95
  96 /**
  97  * test_and_clear_bit - Clear a bit and return its old value
  98  * @nr: Bit to clear
  99  * @addr: Address to count from
 100  */
 101 static inline int test_and_clear_bit(long nr, unsigned long *addr)
 102 {
 103     unsigned long mask = BIT_MASK(nr);
 104     unsigned long *p = addr + BIT_WORD(nr);
 105     unsigned long old = *p;
 106
 107     *p = old & ~mask;
 108     return (old & mask) != 0;
 109 }
 110
 111 /**
 112  * test_and_change_bit - Change a bit and return its old value
 113  * @nr: Bit to change
 114  * @addr: Address to count from
 115  */
 116 static inline int test_and_change_bit(long nr, unsigned long *addr)
 117 {
 118     unsigned long mask = BIT_MASK(nr);
 119     unsigned long *p = addr + BIT_WORD(nr);
 120     unsigned long old = *p;
 121
 122     *p = old ^ mask;
 123     return (old & mask) != 0;
 124 }
 125
 126 /**
 127  * test_bit - Determine whether a bit is set
 128  * @nr: bit number to test
 129  * @addr: Address to start counting from
 130  */
 131 static inline int test_bit(long nr, const unsigned long *addr)
 132 {
 133     return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
 134 }
 135
 136 /**
 137  * find_last_bit - find the last set bit in a memory region
 138  * @addr: The address to start the search at
 139  * @size: The maximum size to search
 140  *
 141  * Returns the bit number of the first set bit, or size.
 142  */
 143 unsigned long find_last_bit(const unsigned long *addr,
 144                             unsigned long size);
 145
 146 /**
 147  * find_next_bit - find the next set bit in a memory region
 148  * @addr: The address to base the search on
 149  * @offset: The bitnumber to start searching at
 150  * @size: The bitmap size in bits
 151  */
 152 unsigned long find_next_bit(const unsigned long *addr,
 153                             unsigned long size,
 154                             unsigned long offset);
 155
 156 /**
 157  * find_next_zero_bit - find the next cleared bit in a memory region
 158  * @addr: The address to base the search on
 159  * @offset: The bitnumber to start searching at
 160  * @size: The bitmap size in bits
 161  */
 162
 163 unsigned long find_next_zero_bit(const unsigned long *addr,
 164                                  unsigned long size,
 165                                  unsigned long offset);
 166
 167 /**
 168  * find_first_bit - find the first set bit in a memory region
 169  * @addr: The address to start the search at
 170  * @size: The maximum size to search
 171  *
 172  * Returns the bit number of the first set bit.
 173  */
 174 static inline unsigned long find_first_bit(const unsigned long *addr,
 175                                            unsigned long size)
 176 {
 177     unsigned long result, tmp;
 178
 179     for (result = 0; result < size; result += BITS_PER_LONG) {
 180         tmp = *addr++;
 181         if (tmp) {
 182             result += ctzl(tmp);
 183             return result < size ? result : size;
 184         }
 185     }
 186     /* Not found */
 187     return size;
 188 }
 189
 190 /**
 191  * find_first_zero_bit - find the first cleared bit in a memory region
 192  * @addr: The address to start the search at
 193  * @size: The maximum size to search
 194  *
 195  * Returns the bit number of the first cleared bit.
 196  */
 197 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
 198                                                 unsigned long size)
 199 {
 200     return find_next_zero_bit(addr, size, 0);
 201 }
 202
 203 static inline unsigned long hweight_long(unsigned long w)
 204 {
 205     unsigned long count;
 206
 207     for (count = 0; w; w >>= 1) {
 208         count += w & 1;
 209     }
 210     return count;
 211 }
 212
 213 /**
 214  * rol8 - rotate an 8-bit value left
 215  * @word: value to rotate
 216  * @shift: bits to roll
 217  */
 218 static inline uint8_t rol8(uint8_t word, unsigned int shift)
 219 {
 220     return (word << shift) | (word >> (8 - shift));
 221 }
 222
 223 /**
 224  * ror8 - rotate an 8-bit value right
 225  * @word: value to rotate
 226  * @shift: bits to roll
 227  */
 228 static inline uint8_t ror8(uint8_t word, unsigned int shift)
 229 {
 230     return (word >> shift) | (word << (8 - shift));
 231 }
 232
 233 /**
 234  * rol16 - rotate a 16-bit value left
 235  * @word: value to rotate
 236  * @shift: bits to roll
 237  */
 238 static inline uint16_t rol16(uint16_t word, unsigned int shift)
 239 {
 240     return (word << shift) | (word >> (16 - shift));
 241 }
 242
 243 /**
 244  * ror16 - rotate a 16-bit value right
 245  * @word: value to rotate
 246  * @shift: bits to roll
 247  */
 248 static inline uint16_t ror16(uint16_t word, unsigned int shift)
 249 {
 250     return (word >> shift) | (word << (16 - shift));
 251 }
 252
 253 /**
 254  * rol32 - rotate a 32-bit value left
 255  * @word: value to rotate
 256  * @shift: bits to roll
 257  */
 258 static inline uint32_t rol32(uint32_t word, unsigned int shift)
 259 {
 260     return (word << shift) | (word >> (32 - shift));
 261 }
 262
 263 /**
 264  * ror32 - rotate a 32-bit value right
 265  * @word: value to rotate
 266  * @shift: bits to roll
 267  */
 268 static inline uint32_t ror32(uint32_t word, unsigned int shift)
 269 {
 270     return (word >> shift) | (word << (32 - shift));
 271 }
 272
 273 /**
 274  * rol64 - rotate a 64-bit value left
 275  * @word: value to rotate
 276  * @shift: bits to roll
 277  */
 278 static inline uint64_t rol64(uint64_t word, unsigned int shift)
 279 {
 280     return (word << shift) | (word >> (64 - shift));
 281 }
 282
 283 /**
 284  * ror64 - rotate a 64-bit value right
 285  * @word: value to rotate
 286  * @shift: bits to roll
 287  */
 288 static inline uint64_t ror64(uint64_t word, unsigned int shift)
 289 {
 290     return (word >> shift) | (word << (64 - shift));
 291 }
 292
 293 /**
 294  * extract32:
 295  * @value: the value to extract the bit field from
 296  * @start: the lowest bit in the bit field (numbered from 0)
 297  * @length: the length of the bit field
 298  *
 299  * Extract from the 32 bit input @value the bit field specified by the
 300  * @start and @length parameters, and return it. The bit field must
 301  * lie entirely within the 32 bit word. It is valid to request that
 302  * all 32 bits are returned (ie @length 32 and @start 0).
 303  *
 304  * Returns: the value of the bit field extracted from the input value.
 305  */
 306 static inline uint32_t extract32(uint32_t value, int start, int length)
 307 {
 308     assert(start >= 0 && length > 0 && length <= 32 - start);
 309     return (value >> start) & (~0U >> (32 - length));
 310 }
 311
 312 /**
 313  * extract64:
 314  * @value: the value to extract the bit field from
 315  * @start: the lowest bit in the bit field (numbered from 0)
 316  * @length: the length of the bit field
 317  *
 318  * Extract from the 64 bit input @value the bit field specified by the
 319  * @start and @length parameters, and return it. The bit field must
 320  * lie entirely within the 64 bit word. It is valid to request that
 321  * all 64 bits are returned (ie @length 64 and @start 0).
 322  *
 323  * Returns: the value of the bit field extracted from the input value.
 324  */
 325 static inline uint64_t extract64(uint64_t value, int start, int length)
 326 {
 327     assert(start >= 0 && length > 0 && length <= 64 - start);
 328     return (value >> start) & (~0ULL >> (64 - length));
 329 }
 330
 331 /**
 332  * sextract32:
 333  * @value: the value to extract the bit field from
 334  * @start: the lowest bit in the bit field (numbered from 0)
 335  * @length: the length of the bit field
 336  *
 337  * Extract from the 32 bit input @value the bit field specified by the
 338  * @start and @length parameters, and return it, sign extended to
 339  * an int32_t (ie with the most significant bit of the field propagated
 340  * to all the upper bits of the return value). The bit field must lie
 341  * entirely within the 32 bit word. It is valid to request that
 342  * all 32 bits are returned (ie @length 32 and @start 0).
 343  *
 344  * Returns: the sign extended value of the bit field extracted from the
 345  * input value.
 346  */
 347 static inline int32_t sextract32(uint32_t value, int start, int length)
 348 {
 349     assert(start >= 0 && length > 0 && length <= 32 - start);
 350     /* Note that this implementation relies on right shift of signed
 351      * integers being an arithmetic shift.
 352      */
 353     return ((int32_t)(value << (32 - length - start))) >> (32 - length);
 354 }
 355
 356 /**
 357  * sextract64:
 358  * @value: the value to extract the bit field from
 359  * @start: the lowest bit in the bit field (numbered from 0)
 360  * @length: the length of the bit field
 361  *
 362  * Extract from the 64 bit input @value the bit field specified by the
 363  * @start and @length parameters, and return it, sign extended to
 364  * an int64_t (ie with the most significant bit of the field propagated
 365  * to all the upper bits of the return value). The bit field must lie
 366  * entirely within the 64 bit word. It is valid to request that
 367  * all 64 bits are returned (ie @length 64 and @start 0).
 368  *
 369  * Returns: the sign extended value of the bit field extracted from the
 370  * input value.
 371  */
 372 static inline int64_t sextract64(uint64_t value, int start, int length)
 373 {
 374     assert(start >= 0 && length > 0 && length <= 64 - start);
 375     /* Note that this implementation relies on right shift of signed
 376      * integers being an arithmetic shift.
 377      */
 378     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
 379 }
 380
 381 /**
 382  * deposit32:
 383  * @value: initial value to insert bit field into
 384  * @start: the lowest bit in the bit field (numbered from 0)
 385  * @length: the length of the bit field
 386  * @fieldval: the value to insert into the bit field
 387  *
 388  * Deposit @fieldval into the 32 bit @value at the bit field specified
 389  * by the @start and @length parameters, and return the modified
 390  * @value. Bits of @value outside the bit field are not modified.
 391  * Bits of @fieldval above the least significant @length bits are
 392  * ignored. The bit field must lie entirely within the 32 bit word.
 393  * It is valid to request that all 32 bits are modified (ie @length
 394  * 32 and @start 0).
 395  *
 396  * Returns: the modified @value.
 397  */
 398 static inline uint32_t deposit32(uint32_t value, int start, int length,
 399                                  uint32_t fieldval)
 400 {
 401     uint32_t mask;
 402     assert(start >= 0 && length > 0 && length <= 32 - start);
 403     mask = (~0U >> (32 - length)) << start;
 404     return (value & ~mask) | ((fieldval << start) & mask);
 405 }
 406
 407 /**
 408  * deposit64:
 409  * @value: initial value to insert bit field into
 410  * @start: the lowest bit in the bit field (numbered from 0)
 411  * @length: the length of the bit field
 412  * @fieldval: the value to insert into the bit field
 413  *
 414  * Deposit @fieldval into the 64 bit @value at the bit field specified
 415  * by the @start and @length parameters, and return the modified
 416  * @value. Bits of @value outside the bit field are not modified.
 417  * Bits of @fieldval above the least significant @length bits are
 418  * ignored. The bit field must lie entirely within the 64 bit word.
 419  * It is valid to request that all 64 bits are modified (ie @length
 420  * 64 and @start 0).
 421  *
 422  * Returns: the modified @value.
 423  */
 424 static inline uint64_t deposit64(uint64_t value, int start, int length,
 425                                  uint64_t fieldval)
 426 {
 427     uint64_t mask;
 428     assert(start >= 0 && length > 0 && length <= 64 - start);
 429     mask = (~0ULL >> (64 - length)) << start;
 430     return (value & ~mask) | ((fieldval << start) & mask);
 431 }
 432
 433 #endif