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 first set bit, or size.
 144  */
 145 unsigned long find_last_bit(const unsigned long *addr,
 146                             unsigned long size);
 147
 148 /**
 149  * find_next_bit - find the next set bit in a memory region
 150  * @addr: The address to base the search on
 151  * @offset: The bitnumber to start searching at
 152  * @size: The bitmap size in bits
 153  */
 154 unsigned long find_next_bit(const unsigned long *addr,
 155                             unsigned long size,
 156                             unsigned long offset);
 157
 158 /**
 159  * find_next_zero_bit - find the next cleared bit in a memory region
 160  * @addr: The address to base the search on
 161  * @offset: The bitnumber to start searching at
 162  * @size: The bitmap size in bits
 163  */
 164
 165 unsigned long find_next_zero_bit(const unsigned long *addr,
 166                                  unsigned long size,
 167                                  unsigned long offset);
 168
 169 /**
 170  * find_first_bit - find the first set bit in a memory region
 171  * @addr: The address to start the search at
 172  * @size: The maximum size to search
 173  *
 174  * Returns the bit number of the first set bit.
 175  */
 176 static inline unsigned long find_first_bit(const unsigned long *addr,
 177                                            unsigned long size)
 178 {
 179     unsigned long result, tmp;
 180
 181     for (result = 0; result < size; result += BITS_PER_LONG) {
 182         tmp = *addr++;
 183         if (tmp) {
 184             result += ctzl(tmp);
 185             return result < size ? result : size;
 186         }
 187     }
 188     /* Not found */
 189     return size;
 190 }
 191
 192 /**
 193  * find_first_zero_bit - find the first cleared bit in a memory region
 194  * @addr: The address to start the search at
 195  * @size: The maximum size to search
 196  *
 197  * Returns the bit number of the first cleared bit.
 198  */
 199 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
 200                                                 unsigned long size)
 201 {
 202     return find_next_zero_bit(addr, size, 0);
 203 }
 204
 205 /**
 206  * rol8 - rotate an 8-bit value left
 207  * @word: value to rotate
 208  * @shift: bits to roll
 209  */
 210 static inline uint8_t rol8(uint8_t word, unsigned int shift)
 211 {
 212     return (word << shift) | (word >> ((8 - shift) & 7));
 213 }
 214
 215 /**
 216  * ror8 - rotate an 8-bit value right
 217  * @word: value to rotate
 218  * @shift: bits to roll
 219  */
 220 static inline uint8_t ror8(uint8_t word, unsigned int shift)
 221 {
 222     return (word >> shift) | (word << ((8 - shift) & 7));
 223 }
 224
 225 /**
 226  * rol16 - rotate a 16-bit value left
 227  * @word: value to rotate
 228  * @shift: bits to roll
 229  */
 230 static inline uint16_t rol16(uint16_t word, unsigned int shift)
 231 {
 232     return (word << shift) | (word >> ((16 - shift) & 15));
 233 }
 234
 235 /**
 236  * ror16 - rotate a 16-bit value right
 237  * @word: value to rotate
 238  * @shift: bits to roll
 239  */
 240 static inline uint16_t ror16(uint16_t word, unsigned int shift)
 241 {
 242     return (word >> shift) | (word << ((16 - shift) & 15));
 243 }
 244
 245 /**
 246  * rol32 - rotate a 32-bit value left
 247  * @word: value to rotate
 248  * @shift: bits to roll
 249  */
 250 static inline uint32_t rol32(uint32_t word, unsigned int shift)
 251 {
 252     return (word << shift) | (word >> ((32 - shift) & 31));
 253 }
 254
 255 /**
 256  * ror32 - rotate a 32-bit value right
 257  * @word: value to rotate
 258  * @shift: bits to roll
 259  */
 260 static inline uint32_t ror32(uint32_t word, unsigned int shift)
 261 {
 262     return (word >> shift) | (word << ((32 - shift) & 31));
 263 }
 264
 265 /**
 266  * rol64 - rotate a 64-bit value left
 267  * @word: value to rotate
 268  * @shift: bits to roll
 269  */
 270 static inline uint64_t rol64(uint64_t word, unsigned int shift)
 271 {
 272     return (word << shift) | (word >> ((64 - shift) & 63));
 273 }
 274
 275 /**
 276  * ror64 - rotate a 64-bit value right
 277  * @word: value to rotate
 278  * @shift: bits to roll
 279  */
 280 static inline uint64_t ror64(uint64_t word, unsigned int shift)
 281 {
 282     return (word >> shift) | (word << ((64 - shift) & 63));
 283 }
 284
 285 /**
 286  * extract32:
 287  * @value: the value to extract the bit field from
 288  * @start: the lowest bit in the bit field (numbered from 0)
 289  * @length: the length of the bit field
 290  *
 291  * Extract from the 32 bit input @value the bit field specified by the
 292  * @start and @length parameters, and return it. The bit field must
 293  * lie entirely within the 32 bit word. It is valid to request that
 294  * all 32 bits are returned (ie @length 32 and @start 0).
 295  *
 296  * Returns: the value of the bit field extracted from the input value.
 297  */
 298 static inline uint32_t extract32(uint32_t value, int start, int length)
 299 {
 300     assert(start >= 0 && length > 0 && length <= 32 - start);
 301     return (value >> start) & (~0U >> (32 - length));
 302 }
 303
 304 /**
 305  * extract8:
 306  * @value: the value to extract the bit field from
 307  * @start: the lowest bit in the bit field (numbered from 0)
 308  * @length: the length of the bit field
 309  *
 310  * Extract from the 8 bit input @value the bit field specified by the
 311  * @start and @length parameters, and return it. The bit field must
 312  * lie entirely within the 8 bit word. It is valid to request that
 313  * all 8 bits are returned (ie @length 8 and @start 0).
 314  *
 315  * Returns: the value of the bit field extracted from the input value.
 316  */
 317 static inline uint8_t extract8(uint8_t value, int start, int length)
 318 {
 319     assert(start >= 0 && length > 0 && length <= 8 - start);
 320     return extract32(value, start, length);
 321 }
 322
 323 /**
 324  * extract16:
 325  * @value: the value to extract the bit field from
 326  * @start: the lowest bit in the bit field (numbered from 0)
 327  * @length: the length of the bit field
 328  *
 329  * Extract from the 16 bit input @value the bit field specified by the
 330  * @start and @length parameters, and return it. The bit field must
 331  * lie entirely within the 16 bit word. It is valid to request that
 332  * all 16 bits are returned (ie @length 16 and @start 0).
 333  *
 334  * Returns: the value of the bit field extracted from the input value.
 335  */
 336 static inline uint16_t extract16(uint16_t value, int start, int length)
 337 {
 338     assert(start >= 0 && length > 0 && length <= 16 - start);
 339     return extract32(value, start, length);
 340 }
 341
 342 /**
 343  * extract64:
 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. The bit field must
 350  * lie entirely within the 64 bit word. It is valid to request that
 351  * all 64 bits are returned (ie @length 64 and @start 0).
 352  *
 353  * Returns: the value of the bit field extracted from the input value.
 354  */
 355 static inline uint64_t extract64(uint64_t value, int start, int length)
 356 {
 357     assert(start >= 0 && length > 0 && length <= 64 - start);
 358     return (value >> start) & (~0ULL >> (64 - length));
 359 }
 360
 361 /**
 362  * sextract32:
 363  * @value: the value to extract the bit field from
 364  * @start: the lowest bit in the bit field (numbered from 0)
 365  * @length: the length of the bit field
 366  *
 367  * Extract from the 32 bit input @value the bit field specified by the
 368  * @start and @length parameters, and return it, sign extended to
 369  * an int32_t (ie with the most significant bit of the field propagated
 370  * to all the upper bits of the return value). The bit field must lie
 371  * entirely within the 32 bit word. It is valid to request that
 372  * all 32 bits are returned (ie @length 32 and @start 0).
 373  *
 374  * Returns: the sign extended value of the bit field extracted from the
 375  * input value.
 376  */
 377 static inline int32_t sextract32(uint32_t value, int start, int length)
 378 {
 379     assert(start >= 0 && length > 0 && length <= 32 - start);
 380     /* Note that this implementation relies on right shift of signed
 381      * integers being an arithmetic shift.
 382      */
 383     return ((int32_t)(value << (32 - length - start))) >> (32 - length);
 384 }
 385
 386 /**
 387  * sextract64:
 388  * @value: the value to extract the bit field from
 389  * @start: the lowest bit in the bit field (numbered from 0)
 390  * @length: the length of the bit field
 391  *
 392  * Extract from the 64 bit input @value the bit field specified by the
 393  * @start and @length parameters, and return it, sign extended to
 394  * an int64_t (ie with the most significant bit of the field propagated
 395  * to all the upper bits of the return value). The bit field must lie
 396  * entirely within the 64 bit word. It is valid to request that
 397  * all 64 bits are returned (ie @length 64 and @start 0).
 398  *
 399  * Returns: the sign extended value of the bit field extracted from the
 400  * input value.
 401  */
 402 static inline int64_t sextract64(uint64_t value, int start, int length)
 403 {
 404     assert(start >= 0 && length > 0 && length <= 64 - start);
 405     /* Note that this implementation relies on right shift of signed
 406      * integers being an arithmetic shift.
 407      */
 408     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
 409 }
 410
 411 /**
 412  * deposit32:
 413  * @value: initial value to insert bit field into
 414  * @start: the lowest bit in the bit field (numbered from 0)
 415  * @length: the length of the bit field
 416  * @fieldval: the value to insert into the bit field
 417  *
 418  * Deposit @fieldval into the 32 bit @value at the bit field specified
 419  * by the @start and @length parameters, and return the modified
 420  * @value. Bits of @value outside the bit field are not modified.
 421  * Bits of @fieldval above the least significant @length bits are
 422  * ignored. The bit field must lie entirely within the 32 bit word.
 423  * It is valid to request that all 32 bits are modified (ie @length
 424  * 32 and @start 0).
 425  *
 426  * Returns: the modified @value.
 427  */
 428 static inline uint32_t deposit32(uint32_t value, int start, int length,
 429                                  uint32_t fieldval)
 430 {
 431     uint32_t mask;
 432     assert(start >= 0 && length > 0 && length <= 32 - start);
 433     mask = (~0U >> (32 - length)) << start;
 434     return (value & ~mask) | ((fieldval << start) & mask);
 435 }
 436
 437 /**
 438  * deposit64:
 439  * @value: initial value to insert bit field into
 440  * @start: the lowest bit in the bit field (numbered from 0)
 441  * @length: the length of the bit field
 442  * @fieldval: the value to insert into the bit field
 443  *
 444  * Deposit @fieldval into the 64 bit @value at the bit field specified
 445  * by the @start and @length parameters, and return the modified
 446  * @value. Bits of @value outside the bit field are not modified.
 447  * Bits of @fieldval above the least significant @length bits are
 448  * ignored. The bit field must lie entirely within the 64 bit word.
 449  * It is valid to request that all 64 bits are modified (ie @length
 450  * 64 and @start 0).
 451  *
 452  * Returns: the modified @value.
 453  */
 454 static inline uint64_t deposit64(uint64_t value, int start, int length,
 455                                  uint64_t fieldval)
 456 {
 457     uint64_t mask;
 458     assert(start >= 0 && length > 0 && length <= 64 - start);
 459     mask = (~0ULL >> (64 - length)) << start;
 460     return (value & ~mask) | ((fieldval << start) & mask);
 461 }
 462
 463 /**
 464  * half_shuffle32:
 465  * @x: 32-bit value (of which only the bottom 16 bits are of interest)
 466  *
 467  * Given an input value::
 468  *
 469  *   xxxx xxxx xxxx xxxx ABCD EFGH IJKL MNOP
 470  *
 471  * return the value where the bottom 16 bits are spread out into
 472  * the odd bits in the word, and the even bits are zeroed::
 473  *
 474  *   0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N 0O0P
 475  *
 476  * Any bits set in the top half of the input are ignored.
 477  *
 478  * Returns: the shuffled bits.
 479  */
 480 static inline uint32_t half_shuffle32(uint32_t x)
 481 {
 482     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 483      * It ignores any bits set in the top half of the input.
 484      */
 485     x = ((x & 0xFF00) << 8) | (x & 0x00FF);
 486     x = ((x << 4) | x) & 0x0F0F0F0F;
 487     x = ((x << 2) | x) & 0x33333333;
 488     x = ((x << 1) | x) & 0x55555555;
 489     return x;
 490 }
 491
 492 /**
 493  * half_shuffle64:
 494  * @x: 64-bit value (of which only the bottom 32 bits are of interest)
 495  *
 496  * Given an input value::
 497  *
 498  *   xxxx xxxx xxxx .... xxxx xxxx ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
 499  *
 500  * return the value where the bottom 32 bits are spread out into
 501  * the odd bits in the word, and the even bits are zeroed::
 502  *
 503  *   0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N .... 0U0V 0W0X 0Y0Z 0a0b 0c0d 0e0f
 504  *
 505  * Any bits set in the top half of the input are ignored.
 506  *
 507  * Returns: the shuffled bits.
 508  */
 509 static inline uint64_t half_shuffle64(uint64_t x)
 510 {
 511     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 512      * It ignores any bits set in the top half of the input.
 513      */
 514     x = ((x & 0xFFFF0000ULL) << 16) | (x & 0xFFFF);
 515     x = ((x << 8) | x) & 0x00FF00FF00FF00FFULL;
 516     x = ((x << 4) | x) & 0x0F0F0F0F0F0F0F0FULL;
 517     x = ((x << 2) | x) & 0x3333333333333333ULL;
 518     x = ((x << 1) | x) & 0x5555555555555555ULL;
 519     return x;
 520 }
 521
 522 /**
 523  * half_unshuffle32:
 524  * @x: 32-bit value (of which only the odd bits are of interest)
 525  *
 526  * Given an input value::
 527  *
 528  *   xAxB xCxD xExF xGxH xIxJ xKxL xMxN xOxP
 529  *
 530  * return the value where all the odd bits are compressed down
 531  * into the low half of the word, and the high half is zeroed::
 532  *
 533  *   0000 0000 0000 0000 ABCD EFGH IJKL MNOP
 534  *
 535  * Any even bits set in the input are ignored.
 536  *
 537  * Returns: the unshuffled bits.
 538  */
 539 static inline uint32_t half_unshuffle32(uint32_t x)
 540 {
 541     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 542      * where it is called an inverse half shuffle.
 543      */
 544     x &= 0x55555555;
 545     x = ((x >> 1) | x) & 0x33333333;
 546     x = ((x >> 2) | x) & 0x0F0F0F0F;
 547     x = ((x >> 4) | x) & 0x00FF00FF;
 548     x = ((x >> 8) | x) & 0x0000FFFF;
 549     return x;
 550 }
 551
 552 /**
 553  * half_unshuffle64:
 554  * @x: 64-bit value (of which only the odd bits are of interest)
 555  *
 556  * Given an input value::
 557  *
 558  *   xAxB xCxD xExF xGxH xIxJ xKxL xMxN .... xUxV xWxX xYxZ xaxb xcxd xexf
 559  *
 560  * return the value where all the odd bits are compressed down
 561  * into the low half of the word, and the high half is zeroed::
 562  *
 563  *   0000 0000 0000 .... 0000 0000 ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
 564  *
 565  * Any even bits set in the input are ignored.
 566  *
 567  * Returns: the unshuffled bits.
 568  */
 569 static inline uint64_t half_unshuffle64(uint64_t x)
 570 {
 571     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 572      * where it is called an inverse half shuffle.
 573      */
 574     x &= 0x5555555555555555ULL;
 575     x = ((x >> 1) | x) & 0x3333333333333333ULL;
 576     x = ((x >> 2) | x) & 0x0F0F0F0F0F0F0F0FULL;
 577     x = ((x >> 4) | x) & 0x00FF00FF00FF00FFULL;
 578     x = ((x >> 8) | x) & 0x0000FFFF0000FFFFULL;
 579     x = ((x >> 16) | x) & 0x00000000FFFFFFFFULL;
 580     return x;
 581 }
 582
 583 #endif