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_MASK(nr)            (1UL << ((nr) % BITS_PER_LONG))
  24 #define BIT_WORD(nr)            ((nr) / BITS_PER_LONG)
  25 #define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
  26
  27 #define MAKE_64BIT_MASK(shift, length) \
  28     (((~0ULL) >> (64 - (length))) << (shift))
  29
  30 /**
  31  * set_bit - Set a bit in memory
  32  * @nr: the bit to set
  33  * @addr: the address to start counting from
  34  */
  35 static inline void set_bit(long nr, unsigned long *addr)
  36 {
  37     unsigned long mask = BIT_MASK(nr);
  38     unsigned long *p = addr + BIT_WORD(nr);
  39
  40     *p  |= mask;
  41 }
  42
  43 /**
  44  * set_bit_atomic - Set a bit in memory atomically
  45  * @nr: the bit to set
  46  * @addr: the address to start counting from
  47  */
  48 static inline void set_bit_atomic(long nr, unsigned long *addr)
  49 {
  50     unsigned long mask = BIT_MASK(nr);
  51     unsigned long *p = addr + BIT_WORD(nr);
  52
  53     atomic_or(p, mask);
  54 }
  55
  56 /**
  57  * clear_bit - Clears a bit in memory
  58  * @nr: Bit to clear
  59  * @addr: Address to start counting from
  60  */
  61 static inline void clear_bit(long nr, unsigned long *addr)
  62 {
  63     unsigned long mask = BIT_MASK(nr);
  64     unsigned long *p = addr + BIT_WORD(nr);
  65
  66     *p &= ~mask;
  67 }
  68
  69 /**
  70  * change_bit - Toggle a bit in memory
  71  * @nr: Bit to change
  72  * @addr: Address to start counting from
  73  */
  74 static inline void change_bit(long nr, unsigned long *addr)
  75 {
  76     unsigned long mask = BIT_MASK(nr);
  77     unsigned long *p = addr + BIT_WORD(nr);
  78
  79     *p ^= mask;
  80 }
  81
  82 /**
  83  * test_and_set_bit - Set a bit and return its old value
  84  * @nr: Bit to set
  85  * @addr: Address to count from
  86  */
  87 static inline int test_and_set_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_clear_bit - Clear a bit and return its old value
  99  * @nr: Bit to clear
 100  * @addr: Address to count from
 101  */
 102 static inline int test_and_clear_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_and_change_bit - Change a bit and return its old value
 114  * @nr: Bit to change
 115  * @addr: Address to count from
 116  */
 117 static inline int test_and_change_bit(long nr, unsigned long *addr)
 118 {
 119     unsigned long mask = BIT_MASK(nr);
 120     unsigned long *p = addr + BIT_WORD(nr);
 121     unsigned long old = *p;
 122
 123     *p = old ^ mask;
 124     return (old & mask) != 0;
 125 }
 126
 127 /**
 128  * test_bit - Determine whether a bit is set
 129  * @nr: bit number to test
 130  * @addr: Address to start counting from
 131  */
 132 static inline int test_bit(long nr, const unsigned long *addr)
 133 {
 134     return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
 135 }
 136
 137 /**
 138  * find_last_bit - find the last set bit in a memory region
 139  * @addr: The address to start the search at
 140  * @size: The maximum size to search
 141  *
 142  * Returns the bit number of the first set bit, or size.
 143  */
 144 unsigned long find_last_bit(const unsigned long *addr,
 145                             unsigned long size);
 146
 147 /**
 148  * find_next_bit - find the next set bit in a memory region
 149  * @addr: The address to base the search on
 150  * @offset: The bitnumber to start searching at
 151  * @size: The bitmap size in bits
 152  */
 153 unsigned long find_next_bit(const unsigned long *addr,
 154                             unsigned long size,
 155                             unsigned long offset);
 156
 157 /**
 158  * find_next_zero_bit - find the next cleared bit in a memory region
 159  * @addr: The address to base the search on
 160  * @offset: The bitnumber to start searching at
 161  * @size: The bitmap size in bits
 162  */
 163
 164 unsigned long find_next_zero_bit(const unsigned long *addr,
 165                                  unsigned long size,
 166                                  unsigned long offset);
 167
 168 /**
 169  * find_first_bit - find the first set bit in a memory region
 170  * @addr: The address to start the search at
 171  * @size: The maximum size to search
 172  *
 173  * Returns the bit number of the first set bit.
 174  */
 175 static inline unsigned long find_first_bit(const unsigned long *addr,
 176                                            unsigned long size)
 177 {
 178     unsigned long result, tmp;
 179
 180     for (result = 0; result < size; result += BITS_PER_LONG) {
 181         tmp = *addr++;
 182         if (tmp) {
 183             result += ctzl(tmp);
 184             return result < size ? result : size;
 185         }
 186     }
 187     /* Not found */
 188     return size;
 189 }
 190
 191 /**
 192  * find_first_zero_bit - find the first cleared bit in a memory region
 193  * @addr: The address to start the search at
 194  * @size: The maximum size to search
 195  *
 196  * Returns the bit number of the first cleared bit.
 197  */
 198 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
 199                                                 unsigned long size)
 200 {
 201     return find_next_zero_bit(addr, size, 0);
 202 }
 203
 204 static inline unsigned long hweight_long(unsigned long w)
 205 {
 206     unsigned long count;
 207
 208     for (count = 0; w; w >>= 1) {
 209         count += w & 1;
 210     }
 211     return count;
 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));
 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));
 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));
 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));
 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));
 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));
 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));
 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));
 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  * extract64:
 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 64 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 64 bit word. It is valid to request that
 322  * all 64 bits are returned (ie @length 64 and @start 0).
 323  *
 324  * Returns: the value of the bit field extracted from the input value.
 325  */
 326 static inline uint64_t extract64(uint64_t value, int start, int length)
 327 {
 328     assert(start >= 0 && length > 0 && length <= 64 - start);
 329     return (value >> start) & (~0ULL >> (64 - length));
 330 }
 331
 332 /**
 333  * sextract32:
 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 32 bit input @value the bit field specified by the
 339  * @start and @length parameters, and return it, sign extended to
 340  * an int32_t (ie with the most significant bit of the field propagated
 341  * to all the upper bits of the return value). The bit field must lie
 342  * entirely within the 32 bit word. It is valid to request that
 343  * all 32 bits are returned (ie @length 32 and @start 0).
 344  *
 345  * Returns: the sign extended value of the bit field extracted from the
 346  * input value.
 347  */
 348 static inline int32_t sextract32(uint32_t value, int start, int length)
 349 {
 350     assert(start >= 0 && length > 0 && length <= 32 - start);
 351     /* Note that this implementation relies on right shift of signed
 352      * integers being an arithmetic shift.
 353      */
 354     return ((int32_t)(value << (32 - length - start))) >> (32 - length);
 355 }
 356
 357 /**
 358  * sextract64:
 359  * @value: the value to extract the bit field from
 360  * @start: the lowest bit in the bit field (numbered from 0)
 361  * @length: the length of the bit field
 362  *
 363  * Extract from the 64 bit input @value the bit field specified by the
 364  * @start and @length parameters, and return it, sign extended to
 365  * an int64_t (ie with the most significant bit of the field propagated
 366  * to all the upper bits of the return value). The bit field must lie
 367  * entirely within the 64 bit word. It is valid to request that
 368  * all 64 bits are returned (ie @length 64 and @start 0).
 369  *
 370  * Returns: the sign extended value of the bit field extracted from the
 371  * input value.
 372  */
 373 static inline int64_t sextract64(uint64_t value, int start, int length)
 374 {
 375     assert(start >= 0 && length > 0 && length <= 64 - start);
 376     /* Note that this implementation relies on right shift of signed
 377      * integers being an arithmetic shift.
 378      */
 379     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
 380 }
 381
 382 /**
 383  * deposit32:
 384  * @value: initial value to insert bit field into
 385  * @start: the lowest bit in the bit field (numbered from 0)
 386  * @length: the length of the bit field
 387  * @fieldval: the value to insert into the bit field
 388  *
 389  * Deposit @fieldval into the 32 bit @value at the bit field specified
 390  * by the @start and @length parameters, and return the modified
 391  * @value. Bits of @value outside the bit field are not modified.
 392  * Bits of @fieldval above the least significant @length bits are
 393  * ignored. The bit field must lie entirely within the 32 bit word.
 394  * It is valid to request that all 32 bits are modified (ie @length
 395  * 32 and @start 0).
 396  *
 397  * Returns: the modified @value.
 398  */
 399 static inline uint32_t deposit32(uint32_t value, int start, int length,
 400                                  uint32_t fieldval)
 401 {
 402     uint32_t mask;
 403     assert(start >= 0 && length > 0 && length <= 32 - start);
 404     mask = (~0U >> (32 - length)) << start;
 405     return (value & ~mask) | ((fieldval << start) & mask);
 406 }
 407
 408 /**
 409  * deposit64:
 410  * @value: initial value to insert bit field into
 411  * @start: the lowest bit in the bit field (numbered from 0)
 412  * @length: the length of the bit field
 413  * @fieldval: the value to insert into the bit field
 414  *
 415  * Deposit @fieldval into the 64 bit @value at the bit field specified
 416  * by the @start and @length parameters, and return the modified
 417  * @value. Bits of @value outside the bit field are not modified.
 418  * Bits of @fieldval above the least significant @length bits are
 419  * ignored. The bit field must lie entirely within the 64 bit word.
 420  * It is valid to request that all 64 bits are modified (ie @length
 421  * 64 and @start 0).
 422  *
 423  * Returns: the modified @value.
 424  */
 425 static inline uint64_t deposit64(uint64_t value, int start, int length,
 426                                  uint64_t fieldval)
 427 {
 428     uint64_t mask;
 429     assert(start >= 0 && length > 0 && length <= 64 - start);
 430     mask = (~0ULL >> (64 - length)) << start;
 431     return (value & ~mask) | ((fieldval << start) & mask);
 432 }
 433
 434 /**
 435  * half_shuffle32:
 436  * @value: 32-bit value (of which only the bottom 16 bits are of interest)
 437  *
 438  * Given an input value:
 439  *  xxxx xxxx xxxx xxxx ABCD EFGH IJKL MNOP
 440  * return the value where the bottom 16 bits are spread out into
 441  * the odd bits in the word, and the even bits are zeroed:
 442  *  0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N 0O0P
 443  *
 444  * Any bits set in the top half of the input are ignored.
 445  *
 446  * Returns: the shuffled bits.
 447  */
 448 static inline uint32_t half_shuffle32(uint32_t x)
 449 {
 450     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 451      * It ignores any bits set in the top half of the input.
 452      */
 453     x = ((x & 0xFF00) << 8) | (x & 0x00FF);
 454     x = ((x << 4) | x) & 0x0F0F0F0F;
 455     x = ((x << 2) | x) & 0x33333333;
 456     x = ((x << 1) | x) & 0x55555555;
 457     return x;
 458 }
 459
 460 /**
 461  * half_shuffle64:
 462  * @value: 64-bit value (of which only the bottom 32 bits are of interest)
 463  *
 464  * Given an input value:
 465  *  xxxx xxxx xxxx .... xxxx xxxx ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
 466  * return the value where the bottom 32 bits are spread out into
 467  * the odd bits in the word, and the even bits are zeroed:
 468  *  0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N .... 0U0V 0W0X 0Y0Z 0a0b 0c0d 0e0f
 469  *
 470  * Any bits set in the top half of the input are ignored.
 471  *
 472  * Returns: the shuffled bits.
 473  */
 474 static inline uint64_t half_shuffle64(uint64_t x)
 475 {
 476     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 477      * It ignores any bits set in the top half of the input.
 478      */
 479     x = ((x & 0xFFFF0000ULL) << 16) | (x & 0xFFFF);
 480     x = ((x << 8) | x) & 0x00FF00FF00FF00FFULL;
 481     x = ((x << 4) | x) & 0x0F0F0F0F0F0F0F0FULL;
 482     x = ((x << 2) | x) & 0x3333333333333333ULL;
 483     x = ((x << 1) | x) & 0x5555555555555555ULL;
 484     return x;
 485 }
 486
 487 /**
 488  * half_unshuffle32:
 489  * @value: 32-bit value (of which only the odd bits are of interest)
 490  *
 491  * Given an input value:
 492  *  xAxB xCxD xExF xGxH xIxJ xKxL xMxN xOxP
 493  * return the value where all the odd bits are compressed down
 494  * into the low half of the word, and the high half is zeroed:
 495  *  0000 0000 0000 0000 ABCD EFGH IJKL MNOP
 496  *
 497  * Any even bits set in the input are ignored.
 498  *
 499  * Returns: the unshuffled bits.
 500  */
 501 static inline uint32_t half_unshuffle32(uint32_t x)
 502 {
 503     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 504      * where it is called an inverse half shuffle.
 505      */
 506     x &= 0x55555555;
 507     x = ((x >> 1) | x) & 0x33333333;
 508     x = ((x >> 2) | x) & 0x0F0F0F0F;
 509     x = ((x >> 4) | x) & 0x00FF00FF;
 510     x = ((x >> 8) | x) & 0x0000FFFF;
 511     return x;
 512 }
 513
 514 /**
 515  * half_unshuffle64:
 516  * @value: 64-bit value (of which only the odd bits are of interest)
 517  *
 518  * Given an input value:
 519  *  xAxB xCxD xExF xGxH xIxJ xKxL xMxN .... xUxV xWxX xYxZ xaxb xcxd xexf
 520  * return the value where all the odd bits are compressed down
 521  * into the low half of the word, and the high half is zeroed:
 522  *  0000 0000 0000 .... 0000 0000 ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
 523  *
 524  * Any even bits set in the input are ignored.
 525  *
 526  * Returns: the unshuffled bits.
 527  */
 528 static inline uint64_t half_unshuffle64(uint64_t x)
 529 {
 530     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
 531      * where it is called an inverse half shuffle.
 532      */
 533     x &= 0x5555555555555555ULL;
 534     x = ((x >> 1) | x) & 0x3333333333333333ULL;
 535     x = ((x >> 2) | x) & 0x0F0F0F0F0F0F0F0FULL;
 536     x = ((x >> 4) | x) & 0x00FF00FF00FF00FFULL;
 537     x = ((x >> 8) | x) & 0x0000FFFF0000FFFFULL;
 538     x = ((x >> 16) | x) & 0x00000000FFFFFFFFULL;
 539     return x;
 540 }
 541
 542 #endif