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