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  * hswap32 - swap 16-bit halfwords within a 32-bit value
 296  * @h: value to swap
 297  */
 298 static inline uint32_t hswap32(uint32_t h)
 299 {
 300     return rol32(h, 16);
 301 }
 302
 303 /**
 304  * hswap64 - swap 16-bit halfwords within a 64-bit value
 305  * @h: value to swap
 306  */
 307 static inline uint64_t hswap64(uint64_t h)
 308 {
 309     uint64_t m = 0x0000ffff0000ffffull;
 310     h = rol64(h, 32);
 311     return ((h & m) << 16) | ((h >> 16) & m);
 312 }
 313
 314 /**
 315  * wswap64 - swap 32-bit words within a 64-bit value
 316  * @h: value to swap
 317  */
 318 static inline uint64_t wswap64(uint64_t h)
 319 {
 320     return rol64(h, 32);
 321 }
 322
 323 /**
 324  * extract32:
 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 32 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 32 bit word. It is valid to request that
 332  * all 32 bits are returned (ie @length 32 and @start 0).
 333  *
 334  * Returns: the value of the bit field extracted from the input value.
 335  */
 336 static inline uint32_t extract32(uint32_t value, int start, int length)
 337 {
 338     assert(start >= 0 && length > 0 && length <= 32 - start);
 339     return (value >> start) & (~0U >> (32 - length));
 340 }
 341
 342 /**
 343  * extract8:
 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 8 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 8 bit word. It is valid to request that
 351  * all 8 bits are returned (ie @length 8 and @start 0).
 352  *
 353  * Returns: the value of the bit field extracted from the input value.
 354  */
 355 static inline uint8_t extract8(uint8_t value, int start, int length)
 356 {
 357     assert(start >= 0 && length > 0 && length <= 8 - start);
 358     return extract32(value, start, length);
 359 }
 360
 361 /**
 362  * extract16:
 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 16 bit input @value the bit field specified by the
 368  * @start and @length parameters, and return it. The bit field must
 369  * lie entirely within the 16 bit word. It is valid to request that
 370  * all 16 bits are returned (ie @length 16 and @start 0).
 371  *
 372  * Returns: the value of the bit field extracted from the input value.
 373  */
 374 static inline uint16_t extract16(uint16_t value, int start, int length)
 375 {
 376     assert(start >= 0 && length > 0 && length <= 16 - start);
 377     return extract32(value, start, length);
 378 }
 379
 380 /**
 381  * extract64:
 382  * @value: the value to extract the bit field from
 383  * @start: the lowest bit in the bit field (numbered from 0)
 384  * @length: the length of the bit field
 385  *
 386  * Extract from the 64 bit input @value the bit field specified by the
 387  * @start and @length parameters, and return it. The bit field must
 388  * lie entirely within the 64 bit word. It is valid to request that
 389  * all 64 bits are returned (ie @length 64 and @start 0).
 390  *
 391  * Returns: the value of the bit field extracted from the input value.
 392  */
 393 static inline uint64_t extract64(uint64_t value, int start, int length)
 394 {
 395     assert(start >= 0 && length > 0 && length <= 64 - start);
 396     return (value >> start) & (~0ULL >> (64 - length));
 397 }
 398
 399 /**
 400  * sextract32:
 401  * @value: the value to extract the bit field from
 402  * @start: the lowest bit in the bit field (numbered from 0)
 403  * @length: the length of the bit field
 404  *
 405  * Extract from the 32 bit input @value the bit field specified by the
 406  * @start and @length parameters, and return it, sign extended to
 407  * an int32_t (ie with the most significant bit of the field propagated
 408  * to all the upper bits of the return value). The bit field must lie
 409  * entirely within the 32 bit word. It is valid to request that
 410  * all 32 bits are returned (ie @length 32 and @start 0).
 411  *
 412  * Returns: the sign extended value of the bit field extracted from the
 413  * input value.
 414  */
 415 static inline int32_t sextract32(uint32_t value, int start, int length)
 416 {
 417     assert(start >= 0 && length > 0 && length <= 32 - start);
 418     /* Note that this implementation relies on right shift of signed
 419      * integers being an arithmetic shift.
 420      */
 421     return ((int32_t)(value << (32 - length - start))) >> (32 - length);
 422 }
 423
 424 /**
 425  * sextract64:
 426  * @value: the value to extract the bit field from
 427  * @start: the lowest bit in the bit field (numbered from 0)
 428  * @length: the length of the bit field
 429  *
 430  * Extract from the 64 bit input @value the bit field specified by the
 431  * @start and @length parameters, and return it, sign extended to
 432  * an int64_t (ie with the most significant bit of the field propagated
 433  * to all the upper bits of the return value). The bit field must lie
 434  * entirely within the 64 bit word. It is valid to request that
 435  * all 64 bits are returned (ie @length 64 and @start 0).
 436  *
 437  * Returns: the sign extended value of the bit field extracted from the
 438  * input value.
 439  */
 440 static inline int64_t sextract64(uint64_t value, int start, int length)
 441 {
 442     assert(start >= 0 && length > 0 && length <= 64 - start);
 443     /* Note that this implementation relies on right shift of signed
 444      * integers being an arithmetic shift.
 445      */
 446     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
 447 }
 448
 449 /**
 450  * deposit32:
 451  * @value: initial value to insert bit field into
 452  * @start: the lowest bit in the bit field (numbered from 0)
 453  * @length: the length of the bit field
 454  * @fieldval: the value to insert into the bit field
 455  *
 456  * Deposit @fieldval into the 32 bit @value at the bit field specified
 457  * by the @start and @length parameters, and return the modified
 458  * @value. Bits of @value outside the bit field are not modified.
 459  * Bits of @fieldval above the least significant @length bits are
 460  * ignored. The bit field must lie entirely within the 32 bit word.
 461  * It is valid to request that all 32 bits are modified (ie @length
 462  * 32 and @start 0).
 463  *
 464  * Returns: the modified @value.
 465  */
 466 static inline uint32_t deposit32(uint32_t value, int start, int length,
 467                                  uint32_t fieldval)
 468 {
 469     uint32_t mask;
 470     assert(start >= 0 && length > 0 && length <= 32 - start);
 471     mask = (~0U >> (32 - length)) << start;
 472     return (value & ~mask) | ((fieldval << start) & mask);
 473 }
 474
 475 /**
 476  * deposit64:
 477  * @value: initial value to insert bit field into
 478  * @start: the lowest bit in the bit field (numbered from 0)
 479  * @length: the length of the bit field
 480  * @fieldval: the value to insert into the bit field
 481  *
 482  * Deposit @fieldval into the 64 bit @value at the bit field specified
 483  * by the @start and @length parameters, and return the modified
 484  * @value. Bits of @value outside the bit field are not modified.
 485  * Bits of @fieldval above the least significant @length bits are
 486  * ignored. The bit field must lie entirely within the 64 bit word.
 487  * It is valid to request that all 64 bits are modified (ie @length
 488  * 64 and @start 0).
 489  *
 490  * Returns: the modified @value.
 491  */
 492 static inline uint64_t deposit64(uint64_t value, int start, int length,
 493                                  uint64_t fieldval)
 494 {
 495     uint64_t mask;
 496     assert(start >= 0 && length > 0 && length <= 64 - start);
 497     mask = (~0ULL >> (64 - length)) << start;
 498     return (value & ~mask) | ((fieldval << start) & mask);
 499 }
 500
 501 /**
 502  * half_shuffle32:
 503  * @x: 32-bit value (of which only the bottom 16 bits are of interest)
 504  *
 505  * Given an input value::
 506  *
 507  *   xxxx xxxx xxxx xxxx ABCD EFGH IJKL MNOP
 508  *
 509  * return the value where the bottom 16 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 0O0P
 513  *
 514  * Any bits set in the top half of the input are ignored.
 515  *
 516  * Returns: the shuffled bits.
 517  */
 518 static inline uint32_t half_shuffle32(uint32_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 & 0xFF00) << 8) | (x & 0x00FF);
 524     x = ((x << 4) | x) & 0x0F0F0F0F;
 525     x = ((x << 2) | x) & 0x33333333;
 526     x = ((x << 1) | x) & 0x55555555;
 527     return x;
 528 }
 529
 530 /**
 531  * half_shuffle64:
 532  * @x: 64-bit value (of which only the bottom 32 bits are of interest)
 533  *
 534  * Given an input value::
 535  *
 536  *   xxxx xxxx xxxx .... xxxx xxxx ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
 537  *
 538  * return the value where the bottom 32 bits are spread out into
 539  * the odd bits in the word, and the even bits are zeroed::
 540  *
 541  *   0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N .... 0U0V 0W0X 0Y0Z 0a0b 0c0d 0e0f
 542  *
 543  * Any bits set in the top half of the input are ignored.
 544  *
 545  * Returns: the shuffled bits.
 546  */
 547 static inline uint64_t half_shuffle64(uint64_t x)
 548 {
 549     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 550      * It ignores any bits set in the top half of the input.
 551      */
 552     x = ((x & 0xFFFF0000ULL) << 16) | (x & 0xFFFF);
 553     x = ((x << 8) | x) & 0x00FF00FF00FF00FFULL;
 554     x = ((x << 4) | x) & 0x0F0F0F0F0F0F0F0FULL;
 555     x = ((x << 2) | x) & 0x3333333333333333ULL;
 556     x = ((x << 1) | x) & 0x5555555555555555ULL;
 557     return x;
 558 }
 559
 560 /**
 561  * half_unshuffle32:
 562  * @x: 32-bit value (of which only the odd bits are of interest)
 563  *
 564  * Given an input value::
 565  *
 566  *   xAxB xCxD xExF xGxH xIxJ xKxL xMxN xOxP
 567  *
 568  * return the value where all the odd bits are compressed down
 569  * into the low half of the word, and the high half is zeroed::
 570  *
 571  *   0000 0000 0000 0000 ABCD EFGH IJKL MNOP
 572  *
 573  * Any even bits set in the input are ignored.
 574  *
 575  * Returns: the unshuffled bits.
 576  */
 577 static inline uint32_t half_unshuffle32(uint32_t x)
 578 {
 579     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 580      * where it is called an inverse half shuffle.
 581      */
 582     x &= 0x55555555;
 583     x = ((x >> 1) | x) & 0x33333333;
 584     x = ((x >> 2) | x) & 0x0F0F0F0F;
 585     x = ((x >> 4) | x) & 0x00FF00FF;
 586     x = ((x >> 8) | x) & 0x0000FFFF;
 587     return x;
 588 }
 589
 590 /**
 591  * half_unshuffle64:
 592  * @x: 64-bit value (of which only the odd bits are of interest)
 593  *
 594  * Given an input value::
 595  *
 596  *   xAxB xCxD xExF xGxH xIxJ xKxL xMxN .... xUxV xWxX xYxZ xaxb xcxd xexf
 597  *
 598  * return the value where all the odd bits are compressed down
 599  * into the low half of the word, and the high half is zeroed::
 600  *
 601  *   0000 0000 0000 .... 0000 0000 ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
 602  *
 603  * Any even bits set in the input are ignored.
 604  *
 605  * Returns: the unshuffled bits.
 606  */
 607 static inline uint64_t half_unshuffle64(uint64_t x)
 608 {
 609     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 610      * where it is called an inverse half shuffle.
 611      */
 612     x &= 0x5555555555555555ULL;
 613     x = ((x >> 1) | x) & 0x3333333333333333ULL;
 614     x = ((x >> 2) | x) & 0x0F0F0F0F0F0F0F0FULL;
 615     x = ((x >> 4) | x) & 0x00FF00FF00FF00FFULL;
 616     x = ((x >> 8) | x) & 0x0000FFFF0000FFFFULL;
 617     x = ((x >> 16) | x) & 0x00000000FFFFFFFFULL;
 618     return x;
 619 }
 620
 621 /**
 622  * bitrev8:
 623  * @x: 8-bit value to be reversed
 624  *
 625  * Given an input value with bits::
 626  *
 627  *   ABCDEFGH
 628  *
 629  * return the value with its bits reversed from left to right::
 630  *
 631  *   HGFEDCBA
 632  *
 633  * Returns: the bit-reversed value.
 634  */
 635 static inline uint8_t bitrev8(uint8_t x)
 636 {
 637     x = ((x >> 1) & 0x55) | ((x << 1) & 0xaa);
 638     x = ((x >> 2) & 0x33) | ((x << 2) & 0xcc);
 639     x = (x >> 4) | (x << 4) ;
 640     return x;
 641 }
 642
 643 #endif