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_ULL(nr)             (1ULL << (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 #define MAKE_64BIT_MASK(shift, length) \
  29     (((~0ULL) >> (64 - (length))) << (shift))
  30
  31 /**
  32  * set_bit - Set a bit in memory
  33  * @nr: the bit to set
  34  * @addr: the address to start counting from
  35  */
  36 static inline void set_bit(long nr, unsigned long *addr)
  37 {
  38     unsigned long mask = BIT_MASK(nr);
  39     unsigned long *p = addr + BIT_WORD(nr);
  40
  41     *p  |= mask;
  42 }
  43
  44 /**
  45  * set_bit_atomic - Set a bit in memory atomically
  46  * @nr: the bit to set
  47  * @addr: the address to start counting from
  48  */
  49 static inline void set_bit_atomic(long nr, unsigned long *addr)
  50 {
  51     unsigned long mask = BIT_MASK(nr);
  52     unsigned long *p = addr + BIT_WORD(nr);
  53
  54     qatomic_or(p, mask);
  55 }
  56
  57 /**
  58  * clear_bit - Clears a bit in memory
  59  * @nr: Bit to clear
  60  * @addr: Address to start counting from
  61  */
  62 static inline void clear_bit(long nr, unsigned long *addr)
  63 {
  64     unsigned long mask = BIT_MASK(nr);
  65     unsigned long *p = addr + BIT_WORD(nr);
  66
  67     *p &= ~mask;
  68 }
  69
  70 /**
  71  * change_bit - Toggle a bit in memory
  72  * @nr: Bit to change
  73  * @addr: Address to start counting from
  74  */
  75 static inline void change_bit(long nr, unsigned long *addr)
  76 {
  77     unsigned long mask = BIT_MASK(nr);
  78     unsigned long *p = addr + BIT_WORD(nr);
  79
  80     *p ^= mask;
  81 }
  82
  83 /**
  84  * test_and_set_bit - Set a bit and return its old value
  85  * @nr: Bit to set
  86  * @addr: Address to count from
  87  */
  88 static inline int test_and_set_bit(long nr, unsigned long *addr)
  89 {
  90     unsigned long mask = BIT_MASK(nr);
  91     unsigned long *p = addr + BIT_WORD(nr);
  92     unsigned long old = *p;
  93
  94     *p = old | mask;
  95     return (old & mask) != 0;
  96 }
  97
  98 /**
  99  * test_and_clear_bit - Clear a bit and return its old value
 100  * @nr: Bit to clear
 101  * @addr: Address to count from
 102  */
 103 static inline int test_and_clear_bit(long nr, unsigned long *addr)
 104 {
 105     unsigned long mask = BIT_MASK(nr);
 106     unsigned long *p = addr + BIT_WORD(nr);
 107     unsigned long old = *p;
 108
 109     *p = old & ~mask;
 110     return (old & mask) != 0;
 111 }
 112
 113 /**
 114  * test_and_change_bit - Change a bit and return its old value
 115  * @nr: Bit to change
 116  * @addr: Address to count from
 117  */
 118 static inline int test_and_change_bit(long nr, unsigned long *addr)
 119 {
 120     unsigned long mask = BIT_MASK(nr);
 121     unsigned long *p = addr + BIT_WORD(nr);
 122     unsigned long old = *p;
 123
 124     *p = old ^ mask;
 125     return (old & mask) != 0;
 126 }
 127
 128 /**
 129  * test_bit - Determine whether a bit is set
 130  * @nr: bit number to test
 131  * @addr: Address to start counting from
 132  */
 133 static inline int test_bit(long nr, const unsigned long *addr)
 134 {
 135     return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
 136 }
 137
 138 /**
 139  * find_last_bit - find the last set bit in a memory region
 140  * @addr: The address to start the search at
 141  * @size: The maximum size to search
 142  *
 143  * Returns the bit number of the last set bit,
 144  * or @size if there is no set bit in the bitmap.
 145  */
 146 unsigned long find_last_bit(const unsigned long *addr,
 147                             unsigned long size);
 148
 149 /**
 150  * find_next_bit - find the next set bit in a memory region
 151  * @addr: The address to base the search on
 152  * @offset: The bitnumber to start searching at
 153  * @size: The bitmap size in bits
 154  *
 155  * Returns the bit number of the next set bit,
 156  * or @size if there are no further set bits in the bitmap.
 157  */
 158 unsigned long find_next_bit(const unsigned long *addr,
 159                             unsigned long size,
 160                             unsigned long offset);
 161
 162 /**
 163  * find_next_zero_bit - find the next cleared bit in a memory region
 164  * @addr: The address to base the search on
 165  * @offset: The bitnumber to start searching at
 166  * @size: The bitmap size in bits
 167  *
 168  * Returns the bit number of the next cleared bit,
 169  * or @size if there are no further clear bits in the bitmap.
 170  */
 171
 172 unsigned long find_next_zero_bit(const unsigned long *addr,
 173                                  unsigned long size,
 174                                  unsigned long offset);
 175
 176 /**
 177  * find_first_bit - find the first set 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 set bit,
 182  * or @size if there is no set bit in the bitmap.
 183  */
 184 static inline unsigned long find_first_bit(const unsigned long *addr,
 185                                            unsigned long size)
 186 {
 187     unsigned long result, tmp;
 188
 189     for (result = 0; result < size; result += BITS_PER_LONG) {
 190         tmp = *addr++;
 191         if (tmp) {
 192             result += ctzl(tmp);
 193             return result < size ? result : size;
 194         }
 195     }
 196     /* Not found */
 197     return size;
 198 }
 199
 200 /**
 201  * find_first_zero_bit - find the first cleared bit in a memory region
 202  * @addr: The address to start the search at
 203  * @size: The maximum size to search
 204  *
 205  * Returns the bit number of the first cleared bit,
 206  * or @size if there is no clear bit in the bitmap.
 207  */
 208 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
 209                                                 unsigned long size)
 210 {
 211     return find_next_zero_bit(addr, size, 0);
 212 }
 213
 214 /**
 215  * rol8 - rotate an 8-bit value left
 216  * @word: value to rotate
 217  * @shift: bits to roll
 218  */
 219 static inline uint8_t rol8(uint8_t word, unsigned int shift)
 220 {
 221     return (word << shift) | (word >> ((8 - shift) & 7));
 222 }
 223
 224 /**
 225  * ror8 - rotate an 8-bit value right
 226  * @word: value to rotate
 227  * @shift: bits to roll
 228  */
 229 static inline uint8_t ror8(uint8_t word, unsigned int shift)
 230 {
 231     return (word >> shift) | (word << ((8 - shift) & 7));
 232 }
 233
 234 /**
 235  * rol16 - rotate a 16-bit value left
 236  * @word: value to rotate
 237  * @shift: bits to roll
 238  */
 239 static inline uint16_t rol16(uint16_t word, unsigned int shift)
 240 {
 241     return (word << shift) | (word >> ((16 - shift) & 15));
 242 }
 243
 244 /**
 245  * ror16 - rotate a 16-bit value right
 246  * @word: value to rotate
 247  * @shift: bits to roll
 248  */
 249 static inline uint16_t ror16(uint16_t word, unsigned int shift)
 250 {
 251     return (word >> shift) | (word << ((16 - shift) & 15));
 252 }
 253
 254 /**
 255  * rol32 - rotate a 32-bit value left
 256  * @word: value to rotate
 257  * @shift: bits to roll
 258  */
 259 static inline uint32_t rol32(uint32_t word, unsigned int shift)
 260 {
 261     return (word << shift) | (word >> ((32 - shift) & 31));
 262 }
 263
 264 /**
 265  * ror32 - rotate a 32-bit value right
 266  * @word: value to rotate
 267  * @shift: bits to roll
 268  */
 269 static inline uint32_t ror32(uint32_t word, unsigned int shift)
 270 {
 271     return (word >> shift) | (word << ((32 - shift) & 31));
 272 }
 273
 274 /**
 275  * rol64 - rotate a 64-bit value left
 276  * @word: value to rotate
 277  * @shift: bits to roll
 278  */
 279 static inline uint64_t rol64(uint64_t word, unsigned int shift)
 280 {
 281     return (word << shift) | (word >> ((64 - shift) & 63));
 282 }
 283
 284 /**
 285  * ror64 - rotate a 64-bit value right
 286  * @word: value to rotate
 287  * @shift: bits to roll
 288  */
 289 static inline uint64_t ror64(uint64_t word, unsigned int shift)
 290 {
 291     return (word >> shift) | (word << ((64 - shift) & 63));
 292 }
 293
 294 /**
 295  * extract32:
 296  * @value: the value to extract the bit field from
 297  * @start: the lowest bit in the bit field (numbered from 0)
 298  * @length: the length of the bit field
 299  *
 300  * Extract from the 32 bit input @value the bit field specified by the
 301  * @start and @length parameters, and return it. The bit field must
 302  * lie entirely within the 32 bit word. It is valid to request that
 303  * all 32 bits are returned (ie @length 32 and @start 0).
 304  *
 305  * Returns: the value of the bit field extracted from the input value.
 306  */
 307 static inline uint32_t extract32(uint32_t value, int start, int length)
 308 {
 309     assert(start >= 0 && length > 0 && length <= 32 - start);
 310     return (value >> start) & (~0U >> (32 - length));
 311 }
 312
 313 /**
 314  * extract8:
 315  * @value: the value to extract the bit field from
 316  * @start: the lowest bit in the bit field (numbered from 0)
 317  * @length: the length of the bit field
 318  *
 319  * Extract from the 8 bit input @value the bit field specified by the
 320  * @start and @length parameters, and return it. The bit field must
 321  * lie entirely within the 8 bit word. It is valid to request that
 322  * all 8 bits are returned (ie @length 8 and @start 0).
 323  *
 324  * Returns: the value of the bit field extracted from the input value.
 325  */
 326 static inline uint8_t extract8(uint8_t value, int start, int length)
 327 {
 328     assert(start >= 0 && length > 0 && length <= 8 - start);
 329     return extract32(value, start, length);
 330 }
 331
 332 /**
 333  * extract16:
 334  * @value: the value to extract the bit field from
 335  * @start: the lowest bit in the bit field (numbered from 0)
 336  * @length: the length of the bit field
 337  *
 338  * Extract from the 16 bit input @value the bit field specified by the
 339  * @start and @length parameters, and return it. The bit field must
 340  * lie entirely within the 16 bit word. It is valid to request that
 341  * all 16 bits are returned (ie @length 16 and @start 0).
 342  *
 343  * Returns: the value of the bit field extracted from the input value.
 344  */
 345 static inline uint16_t extract16(uint16_t value, int start, int length)
 346 {
 347     assert(start >= 0 && length > 0 && length <= 16 - start);
 348     return extract32(value, start, length);
 349 }
 350
 351 /**
 352  * extract64:
 353  * @value: the value to extract the bit field from
 354  * @start: the lowest bit in the bit field (numbered from 0)
 355  * @length: the length of the bit field
 356  *
 357  * Extract from the 64 bit input @value the bit field specified by the
 358  * @start and @length parameters, and return it. The bit field must
 359  * lie entirely within the 64 bit word. It is valid to request that
 360  * all 64 bits are returned (ie @length 64 and @start 0).
 361  *
 362  * Returns: the value of the bit field extracted from the input value.
 363  */
 364 static inline uint64_t extract64(uint64_t value, int start, int length)
 365 {
 366     assert(start >= 0 && length > 0 && length <= 64 - start);
 367     return (value >> start) & (~0ULL >> (64 - length));
 368 }
 369
 370 /**
 371  * sextract32:
 372  * @value: the value to extract the bit field from
 373  * @start: the lowest bit in the bit field (numbered from 0)
 374  * @length: the length of the bit field
 375  *
 376  * Extract from the 32 bit input @value the bit field specified by the
 377  * @start and @length parameters, and return it, sign extended to
 378  * an int32_t (ie with the most significant bit of the field propagated
 379  * to all the upper bits of the return value). The bit field must lie
 380  * entirely within the 32 bit word. It is valid to request that
 381  * all 32 bits are returned (ie @length 32 and @start 0).
 382  *
 383  * Returns: the sign extended value of the bit field extracted from the
 384  * input value.
 385  */
 386 static inline int32_t sextract32(uint32_t value, int start, int length)
 387 {
 388     assert(start >= 0 && length > 0 && length <= 32 - start);
 389     /* Note that this implementation relies on right shift of signed
 390      * integers being an arithmetic shift.
 391      */
 392     return ((int32_t)(value << (32 - length - start))) >> (32 - length);
 393 }
 394
 395 /**
 396  * sextract64:
 397  * @value: the value to extract the bit field from
 398  * @start: the lowest bit in the bit field (numbered from 0)
 399  * @length: the length of the bit field
 400  *
 401  * Extract from the 64 bit input @value the bit field specified by the
 402  * @start and @length parameters, and return it, sign extended to
 403  * an int64_t (ie with the most significant bit of the field propagated
 404  * to all the upper bits of the return value). The bit field must lie
 405  * entirely within the 64 bit word. It is valid to request that
 406  * all 64 bits are returned (ie @length 64 and @start 0).
 407  *
 408  * Returns: the sign extended value of the bit field extracted from the
 409  * input value.
 410  */
 411 static inline int64_t sextract64(uint64_t value, int start, int length)
 412 {
 413     assert(start >= 0 && length > 0 && length <= 64 - start);
 414     /* Note that this implementation relies on right shift of signed
 415      * integers being an arithmetic shift.
 416      */
 417     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
 418 }
 419
 420 /**
 421  * deposit32:
 422  * @value: initial value to insert bit field into
 423  * @start: the lowest bit in the bit field (numbered from 0)
 424  * @length: the length of the bit field
 425  * @fieldval: the value to insert into the bit field
 426  *
 427  * Deposit @fieldval into the 32 bit @value at the bit field specified
 428  * by the @start and @length parameters, and return the modified
 429  * @value. Bits of @value outside the bit field are not modified.
 430  * Bits of @fieldval above the least significant @length bits are
 431  * ignored. The bit field must lie entirely within the 32 bit word.
 432  * It is valid to request that all 32 bits are modified (ie @length
 433  * 32 and @start 0).
 434  *
 435  * Returns: the modified @value.
 436  */
 437 static inline uint32_t deposit32(uint32_t value, int start, int length,
 438                                  uint32_t fieldval)
 439 {
 440     uint32_t mask;
 441     assert(start >= 0 && length > 0 && length <= 32 - start);
 442     mask = (~0U >> (32 - length)) << start;
 443     return (value & ~mask) | ((fieldval << start) & mask);
 444 }
 445
 446 /**
 447  * deposit64:
 448  * @value: initial value to insert bit field into
 449  * @start: the lowest bit in the bit field (numbered from 0)
 450  * @length: the length of the bit field
 451  * @fieldval: the value to insert into the bit field
 452  *
 453  * Deposit @fieldval into the 64 bit @value at the bit field specified
 454  * by the @start and @length parameters, and return the modified
 455  * @value. Bits of @value outside the bit field are not modified.
 456  * Bits of @fieldval above the least significant @length bits are
 457  * ignored. The bit field must lie entirely within the 64 bit word.
 458  * It is valid to request that all 64 bits are modified (ie @length
 459  * 64 and @start 0).
 460  *
 461  * Returns: the modified @value.
 462  */
 463 static inline uint64_t deposit64(uint64_t value, int start, int length,
 464                                  uint64_t fieldval)
 465 {
 466     uint64_t mask;
 467     assert(start >= 0 && length > 0 && length <= 64 - start);
 468     mask = (~0ULL >> (64 - length)) << start;
 469     return (value & ~mask) | ((fieldval << start) & mask);
 470 }
 471
 472 /**
 473  * half_shuffle32:
 474  * @x: 32-bit value (of which only the bottom 16 bits are of interest)
 475  *
 476  * Given an input value::
 477  *
 478  *   xxxx xxxx xxxx xxxx ABCD EFGH IJKL MNOP
 479  *
 480  * return the value where the bottom 16 bits are spread out into
 481  * the odd bits in the word, and the even bits are zeroed::
 482  *
 483  *   0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N 0O0P
 484  *
 485  * Any bits set in the top half of the input are ignored.
 486  *
 487  * Returns: the shuffled bits.
 488  */
 489 static inline uint32_t half_shuffle32(uint32_t x)
 490 {
 491     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 492      * It ignores any bits set in the top half of the input.
 493      */
 494     x = ((x & 0xFF00) << 8) | (x & 0x00FF);
 495     x = ((x << 4) | x) & 0x0F0F0F0F;
 496     x = ((x << 2) | x) & 0x33333333;
 497     x = ((x << 1) | x) & 0x55555555;
 498     return x;
 499 }
 500
 501 /**
 502  * half_shuffle64:
 503  * @x: 64-bit value (of which only the bottom 32 bits are of interest)
 504  *
 505  * Given an input value::
 506  *
 507  *   xxxx xxxx xxxx .... xxxx xxxx ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
 508  *
 509  * return the value where the bottom 32 bits are spread out into
 510  * the odd bits in the word, and the even bits are zeroed::
 511  *
 512  *   0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N .... 0U0V 0W0X 0Y0Z 0a0b 0c0d 0e0f
 513  *
 514  * Any bits set in the top half of the input are ignored.
 515  *
 516  * Returns: the shuffled bits.
 517  */
 518 static inline uint64_t half_shuffle64(uint64_t x)
 519 {
 520     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 521      * It ignores any bits set in the top half of the input.
 522      */
 523     x = ((x & 0xFFFF0000ULL) << 16) | (x & 0xFFFF);
 524     x = ((x << 8) | x) & 0x00FF00FF00FF00FFULL;
 525     x = ((x << 4) | x) & 0x0F0F0F0F0F0F0F0FULL;
 526     x = ((x << 2) | x) & 0x3333333333333333ULL;
 527     x = ((x << 1) | x) & 0x5555555555555555ULL;
 528     return x;
 529 }
 530
 531 /**
 532  * half_unshuffle32:
 533  * @x: 32-bit value (of which only the odd bits are of interest)
 534  *
 535  * Given an input value::
 536  *
 537  *   xAxB xCxD xExF xGxH xIxJ xKxL xMxN xOxP
 538  *
 539  * return the value where all the odd bits are compressed down
 540  * into the low half of the word, and the high half is zeroed::
 541  *
 542  *   0000 0000 0000 0000 ABCD EFGH IJKL MNOP
 543  *
 544  * Any even bits set in the input are ignored.
 545  *
 546  * Returns: the unshuffled bits.
 547  */
 548 static inline uint32_t half_unshuffle32(uint32_t x)
 549 {
 550     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 551      * where it is called an inverse half shuffle.
 552      */
 553     x &= 0x55555555;
 554     x = ((x >> 1) | x) & 0x33333333;
 555     x = ((x >> 2) | x) & 0x0F0F0F0F;
 556     x = ((x >> 4) | x) & 0x00FF00FF;
 557     x = ((x >> 8) | x) & 0x0000FFFF;
 558     return x;
 559 }
 560
 561 /**
 562  * half_unshuffle64:
 563  * @x: 64-bit value (of which only the odd bits are of interest)
 564  *
 565  * Given an input value::
 566  *
 567  *   xAxB xCxD xExF xGxH xIxJ xKxL xMxN .... xUxV xWxX xYxZ xaxb xcxd xexf
 568  *
 569  * return the value where all the odd bits are compressed down
 570  * into the low half of the word, and the high half is zeroed::
 571  *
 572  *   0000 0000 0000 .... 0000 0000 ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
 573  *
 574  * Any even bits set in the input are ignored.
 575  *
 576  * Returns: the unshuffled bits.
 577  */
 578 static inline uint64_t half_unshuffle64(uint64_t x)
 579 {
 580     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 581      * where it is called an inverse half shuffle.
 582      */
 583     x &= 0x5555555555555555ULL;
 584     x = ((x >> 1) | x) & 0x3333333333333333ULL;
 585     x = ((x >> 2) | x) & 0x0F0F0F0F0F0F0F0FULL;
 586     x = ((x >> 4) | x) & 0x00FF00FF00FF00FFULL;
 587     x = ((x >> 8) | x) & 0x0000FFFF0000FFFFULL;
 588     x = ((x >> 16) | x) & 0x00000000FFFFFFFFULL;
 589     return x;
 590 }
 591
 592 #endif