| 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 | #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long)) |
| 22 | #define BITS_TO_U32S(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(uint32_t)) |
| 23 | |
| 24 | #define BIT(nr) (1UL << (nr)) |
| 25 | #define BIT_ULL(nr) (1ULL << (nr)) |
| 26 | |
| 27 | #define MAKE_64BIT_MASK(shift, length) \ |
| 28 | (((~0ULL) >> (64 - (length))) << (shift)) |
| 29 | |
| 30 | /** |
| 31 | * DOC: Functions operating on arrays of bits |
| 32 | * |
| 33 | * We provide a set of functions which work on arbitrary-length arrays of |
| 34 | * bits. These come in several flavours which vary in what the type of the |
| 35 | * underlying storage for the bits is: |
| 36 | * |
| 37 | * - Bits stored in an array of 'unsigned long': set_bit(), clear_bit(), etc |
| 38 | * - Bits stored in an array of 'uint32_t': set_bit32(), clear_bit32(), etc |
| 39 | * |
| 40 | * Because the 'unsigned long' type has a size which varies between |
| 41 | * host systems, the versions using 'uint32_t' are often preferable. |
| 42 | * This is particularly the case in a device model where there may |
| 43 | * be some guest-visible register view of the bit array. |
| 44 | * |
| 45 | * We do not currently implement uint32_t versions of find_last_bit(), |
| 46 | * find_next_bit(), find_next_zero_bit() or find_first_zero_bit(), |
| 47 | * because we haven't yet needed them. If you need them you should |
| 48 | * implement them similarly to the 'unsigned long' versions. |
| 49 | * |
| 50 | * You can declare a bitmap to be used with these functions via the |
| 51 | * DECLARE_BITMAP and DECLARE_BITMAP32 macros in bitmap.h. |
| 52 | */ |
| 53 | |
| 54 | /** |
| 55 | * DOC: 'unsigned long' bit array APIs |
| 56 | */ |
| 57 | |
| 58 | #define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG)) |
| 59 | #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) |
| 60 | |
| 61 | /** |
| 62 | * set_bit - Set a bit in memory |
| 63 | * @nr: the bit to set |
| 64 | * @addr: the address to start counting from |
| 65 | */ |
| 66 | static inline void set_bit(long nr, unsigned long *addr) |
| 67 | { |
| 68 | unsigned long mask = BIT_MASK(nr); |
| 69 | unsigned long *p = addr + BIT_WORD(nr); |
| 70 | |
| 71 | *p |= mask; |
| 72 | } |
| 73 | |
| 74 | /** |
| 75 | * set_bit_atomic - Set a bit in memory atomically |
| 76 | * @nr: the bit to set |
| 77 | * @addr: the address to start counting from |
| 78 | */ |
| 79 | static inline void set_bit_atomic(long nr, unsigned long *addr) |
| 80 | { |
| 81 | unsigned long mask = BIT_MASK(nr); |
| 82 | unsigned long *p = addr + BIT_WORD(nr); |
| 83 | |
| 84 | qatomic_or(p, mask); |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * clear_bit - Clears a bit in memory |
| 89 | * @nr: Bit to clear |
| 90 | * @addr: Address to start counting from |
| 91 | */ |
| 92 | static inline void clear_bit(long nr, unsigned long *addr) |
| 93 | { |
| 94 | unsigned long mask = BIT_MASK(nr); |
| 95 | unsigned long *p = addr + BIT_WORD(nr); |
| 96 | |
| 97 | *p &= ~mask; |
| 98 | } |
| 99 | |
| 100 | /** |
| 101 | * clear_bit_atomic - Clears a bit in memory atomically |
| 102 | * @nr: Bit to clear |
| 103 | * @addr: Address to start counting from |
| 104 | */ |
| 105 | static inline void clear_bit_atomic(long nr, unsigned long *addr) |
| 106 | { |
| 107 | unsigned long mask = BIT_MASK(nr); |
| 108 | unsigned long *p = addr + BIT_WORD(nr); |
| 109 | |
| 110 | return qatomic_and(p, ~mask); |
| 111 | } |
| 112 | |
| 113 | /** |
| 114 | * change_bit - Toggle a bit in memory |
| 115 | * @nr: Bit to change |
| 116 | * @addr: Address to start counting from |
| 117 | */ |
| 118 | static inline void change_bit(long nr, unsigned long *addr) |
| 119 | { |
| 120 | unsigned long mask = BIT_MASK(nr); |
| 121 | unsigned long *p = addr + BIT_WORD(nr); |
| 122 | |
| 123 | *p ^= mask; |
| 124 | } |
| 125 | |
| 126 | /** |
| 127 | * test_and_set_bit - Set a bit and return its old value |
| 128 | * @nr: Bit to set |
| 129 | * @addr: Address to count from |
| 130 | */ |
| 131 | static inline int test_and_set_bit(long nr, unsigned long *addr) |
| 132 | { |
| 133 | unsigned long mask = BIT_MASK(nr); |
| 134 | unsigned long *p = addr + BIT_WORD(nr); |
| 135 | unsigned long old = *p; |
| 136 | |
| 137 | *p = old | mask; |
| 138 | return (old & mask) != 0; |
| 139 | } |
| 140 | |
| 141 | /** |
| 142 | * test_and_clear_bit - Clear a bit and return its old value |
| 143 | * @nr: Bit to clear |
| 144 | * @addr: Address to count from |
| 145 | */ |
| 146 | static inline int test_and_clear_bit(long nr, unsigned long *addr) |
| 147 | { |
| 148 | unsigned long mask = BIT_MASK(nr); |
| 149 | unsigned long *p = addr + BIT_WORD(nr); |
| 150 | unsigned long old = *p; |
| 151 | |
| 152 | *p = old & ~mask; |
| 153 | return (old & mask) != 0; |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * test_and_change_bit - Change a bit and return its old value |
| 158 | * @nr: Bit to change |
| 159 | * @addr: Address to count from |
| 160 | */ |
| 161 | static inline int test_and_change_bit(long nr, unsigned long *addr) |
| 162 | { |
| 163 | unsigned long mask = BIT_MASK(nr); |
| 164 | unsigned long *p = addr + BIT_WORD(nr); |
| 165 | unsigned long old = *p; |
| 166 | |
| 167 | *p = old ^ mask; |
| 168 | return (old & mask) != 0; |
| 169 | } |
| 170 | |
| 171 | /** |
| 172 | * test_bit - Determine whether a bit is set |
| 173 | * @nr: bit number to test |
| 174 | * @addr: Address to start counting from |
| 175 | */ |
| 176 | static inline int test_bit(long nr, const unsigned long *addr) |
| 177 | { |
| 178 | return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); |
| 179 | } |
| 180 | |
| 181 | /** |
| 182 | * find_last_bit - find the last set bit in a memory region |
| 183 | * @addr: The address to start the search at |
| 184 | * @size: The maximum size to search |
| 185 | * |
| 186 | * Returns the bit number of the last set bit, |
| 187 | * or @size if there is no set bit in the bitmap. |
| 188 | */ |
| 189 | unsigned long find_last_bit(const unsigned long *addr, |
| 190 | unsigned long size); |
| 191 | |
| 192 | /** |
| 193 | * find_next_bit - find the next set bit in a memory region |
| 194 | * @addr: The address to base the search on |
| 195 | * @offset: The bitnumber to start searching at |
| 196 | * @size: The bitmap size in bits |
| 197 | * |
| 198 | * Returns the bit number of the next set bit, |
| 199 | * or @size if there are no further set bits in the bitmap. |
| 200 | */ |
| 201 | unsigned long find_next_bit(const unsigned long *addr, |
| 202 | unsigned long size, |
| 203 | unsigned long offset); |
| 204 | |
| 205 | /** |
| 206 | * find_next_zero_bit - find the next cleared bit in a memory region |
| 207 | * @addr: The address to base the search on |
| 208 | * @offset: The bitnumber to start searching at |
| 209 | * @size: The bitmap size in bits |
| 210 | * |
| 211 | * Returns the bit number of the next cleared bit, |
| 212 | * or @size if there are no further clear bits in the bitmap. |
| 213 | */ |
| 214 | |
| 215 | unsigned long find_next_zero_bit(const unsigned long *addr, |
| 216 | unsigned long size, |
| 217 | unsigned long offset); |
| 218 | |
| 219 | /** |
| 220 | * find_first_bit - find the first set bit in a memory region |
| 221 | * @addr: The address to start the search at |
| 222 | * @size: The maximum size to search |
| 223 | * |
| 224 | * Returns the bit number of the first set bit, |
| 225 | * or @size if there is no set bit in the bitmap. |
| 226 | */ |
| 227 | static inline unsigned long find_first_bit(const unsigned long *addr, |
| 228 | unsigned long size) |
| 229 | { |
| 230 | unsigned long result, tmp; |
| 231 | |
| 232 | for (result = 0; result < size; result += BITS_PER_LONG) { |
| 233 | tmp = *addr++; |
| 234 | if (tmp) { |
| 235 | result += ctzl(tmp); |
| 236 | return result < size ? result : size; |
| 237 | } |
| 238 | } |
| 239 | /* Not found */ |
| 240 | return size; |
| 241 | } |
| 242 | |
| 243 | /** |
| 244 | * find_first_zero_bit - find the first cleared bit in a memory region |
| 245 | * @addr: The address to start the search at |
| 246 | * @size: The maximum size to search |
| 247 | * |
| 248 | * Returns the bit number of the first cleared bit, |
| 249 | * or @size if there is no clear bit in the bitmap. |
| 250 | */ |
| 251 | static inline unsigned long find_first_zero_bit(const unsigned long *addr, |
| 252 | unsigned long size) |
| 253 | { |
| 254 | return find_next_zero_bit(addr, size, 0); |
| 255 | } |
| 256 | |
| 257 | /** |
| 258 | * DOC: 'uint32_t' bit array APIs |
| 259 | */ |
| 260 | |
| 261 | #define BIT32_MASK(nr) (1UL << ((nr) % 32)) |
| 262 | #define BIT32_WORD(nr) ((nr) / 32) |
| 263 | |
| 264 | /** |
| 265 | * set_bit32 - Set a bit in memory |
| 266 | * @nr: the bit to set |
| 267 | * @addr: the address to start counting from |
| 268 | */ |
| 269 | static inline void set_bit32(long nr, uint32_t *addr) |
| 270 | { |
| 271 | uint32_t mask = BIT32_MASK(nr); |
| 272 | uint32_t *p = addr + BIT32_WORD(nr); |
| 273 | |
| 274 | *p |= mask; |
| 275 | } |
| 276 | |
| 277 | /** |
| 278 | * set_bit32_atomic - Set a bit in memory atomically |
| 279 | * @nr: the bit to set |
| 280 | * @addr: the address to start counting from |
| 281 | */ |
| 282 | static inline void set_bit32_atomic(long nr, uint32_t *addr) |
| 283 | { |
| 284 | uint32_t mask = BIT32_MASK(nr); |
| 285 | uint32_t *p = addr + BIT32_WORD(nr); |
| 286 | |
| 287 | qatomic_or(p, mask); |
| 288 | } |
| 289 | |
| 290 | /** |
| 291 | * clear_bit32 - Clears a bit in memory |
| 292 | * @nr: Bit to clear |
| 293 | * @addr: Address to start counting from |
| 294 | */ |
| 295 | static inline void clear_bit32(long nr, uint32_t *addr) |
| 296 | { |
| 297 | uint32_t mask = BIT32_MASK(nr); |
| 298 | uint32_t *p = addr + BIT32_WORD(nr); |
| 299 | |
| 300 | *p &= ~mask; |
| 301 | } |
| 302 | |
| 303 | /** |
| 304 | * clear_bit32_atomic - Clears a bit in memory atomically |
| 305 | * @nr: Bit to clear |
| 306 | * @addr: Address to start counting from |
| 307 | */ |
| 308 | static inline void clear_bit32_atomic(long nr, uint32_t *addr) |
| 309 | { |
| 310 | uint32_t mask = BIT32_MASK(nr); |
| 311 | uint32_t *p = addr + BIT32_WORD(nr); |
| 312 | |
| 313 | return qatomic_and(p, ~mask); |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * change_bit32 - Toggle a bit in memory |
| 318 | * @nr: Bit to change |
| 319 | * @addr: Address to start counting from |
| 320 | */ |
| 321 | static inline void change_bit32(long nr, uint32_t *addr) |
| 322 | { |
| 323 | uint32_t mask = BIT32_MASK(nr); |
| 324 | uint32_t *p = addr + BIT32_WORD(nr); |
| 325 | |
| 326 | *p ^= mask; |
| 327 | } |
| 328 | |
| 329 | /** |
| 330 | * test_and_set_bit32 - Set a bit and return its old value |
| 331 | * @nr: Bit to set |
| 332 | * @addr: Address to count from |
| 333 | */ |
| 334 | static inline int test_and_set_bit32(long nr, uint32_t *addr) |
| 335 | { |
| 336 | uint32_t mask = BIT32_MASK(nr); |
| 337 | uint32_t *p = addr + BIT32_WORD(nr); |
| 338 | uint32_t old = *p; |
| 339 | |
| 340 | *p = old | mask; |
| 341 | return (old & mask) != 0; |
| 342 | } |
| 343 | |
| 344 | /** |
| 345 | * test_and_clear_bit32 - Clear a bit and return its old value |
| 346 | * @nr: Bit to clear |
| 347 | * @addr: Address to count from |
| 348 | */ |
| 349 | static inline int test_and_clear_bit32(long nr, uint32_t *addr) |
| 350 | { |
| 351 | uint32_t mask = BIT32_MASK(nr); |
| 352 | uint32_t *p = addr + BIT32_WORD(nr); |
| 353 | uint32_t old = *p; |
| 354 | |
| 355 | *p = old & ~mask; |
| 356 | return (old & mask) != 0; |
| 357 | } |
| 358 | |
| 359 | /** |
| 360 | * test_and_change_bit32 - Change a bit and return its old value |
| 361 | * @nr: Bit to change |
| 362 | * @addr: Address to count from |
| 363 | */ |
| 364 | static inline int test_and_change_bit32(long nr, uint32_t *addr) |
| 365 | { |
| 366 | uint32_t mask = BIT32_MASK(nr); |
| 367 | uint32_t *p = addr + BIT32_WORD(nr); |
| 368 | uint32_t old = *p; |
| 369 | |
| 370 | *p = old ^ mask; |
| 371 | return (old & mask) != 0; |
| 372 | } |
| 373 | |
| 374 | /** |
| 375 | * test_bit32 - Determine whether a bit is set |
| 376 | * @nr: bit number to test |
| 377 | * @addr: Address to start counting from |
| 378 | */ |
| 379 | static inline int test_bit32(long nr, const uint32_t *addr) |
| 380 | { |
| 381 | return 1U & (addr[BIT32_WORD(nr)] >> (nr & 31)); |
| 382 | } |
| 383 | |
| 384 | /** |
| 385 | * find_first_bit32 - find the first set bit in a memory region |
| 386 | * @addr: The address to start the search at |
| 387 | * @size: The maximum size to search |
| 388 | * |
| 389 | * Returns the bit number of the first set bit, |
| 390 | * or @size if there is no set bit in the bitmap. |
| 391 | */ |
| 392 | static inline uint32_t find_first_bit32(const uint32_t *addr, uint32_t size) |
| 393 | { |
| 394 | uint32_t result; |
| 395 | |
| 396 | for (result = 0; result < size; result += 32) { |
| 397 | uint32_t tmp = *addr++; |
| 398 | if (tmp) { |
| 399 | result += ctz32(tmp); |
| 400 | return result < size ? result : size; |
| 401 | } |
| 402 | } |
| 403 | /* Not found */ |
| 404 | return size; |
| 405 | } |
| 406 | |
| 407 | /** |
| 408 | * DOC: Miscellaneous bit operations on single values |
| 409 | * |
| 410 | * These functions are a collection of useful operations |
| 411 | * (rotations, bit extract, bit deposit, etc) on single |
| 412 | * integer values. |
| 413 | */ |
| 414 | |
| 415 | /** |
| 416 | * rol8 - rotate an 8-bit value left |
| 417 | * @word: value to rotate |
| 418 | * @shift: bits to roll |
| 419 | */ |
| 420 | static inline uint8_t rol8(uint8_t word, unsigned int shift) |
| 421 | { |
| 422 | return (word << (shift & 7)) | (word >> (-shift & 7)); |
| 423 | } |
| 424 | |
| 425 | /** |
| 426 | * ror8 - rotate an 8-bit value right |
| 427 | * @word: value to rotate |
| 428 | * @shift: bits to roll |
| 429 | */ |
| 430 | static inline uint8_t ror8(uint8_t word, unsigned int shift) |
| 431 | { |
| 432 | return (word >> (shift & 7)) | (word << (-shift & 7)); |
| 433 | } |
| 434 | |
| 435 | /** |
| 436 | * rol16 - rotate a 16-bit value left |
| 437 | * @word: value to rotate |
| 438 | * @shift: bits to roll |
| 439 | */ |
| 440 | static inline uint16_t rol16(uint16_t word, unsigned int shift) |
| 441 | { |
| 442 | return (word << (shift & 15)) | (word >> (-shift & 15)); |
| 443 | } |
| 444 | |
| 445 | /** |
| 446 | * ror16 - rotate a 16-bit value right |
| 447 | * @word: value to rotate |
| 448 | * @shift: bits to roll |
| 449 | */ |
| 450 | static inline uint16_t ror16(uint16_t word, unsigned int shift) |
| 451 | { |
| 452 | return (word >> (shift & 15)) | (word << (-shift & 15)); |
| 453 | } |
| 454 | |
| 455 | /** |
| 456 | * rol32 - rotate a 32-bit value left |
| 457 | * @word: value to rotate |
| 458 | * @shift: bits to roll |
| 459 | */ |
| 460 | static inline uint32_t rol32(uint32_t word, unsigned int shift) |
| 461 | { |
| 462 | return (word << (shift & 31)) | (word >> (-shift & 31)); |
| 463 | } |
| 464 | |
| 465 | /** |
| 466 | * ror32 - rotate a 32-bit value right |
| 467 | * @word: value to rotate |
| 468 | * @shift: bits to roll |
| 469 | */ |
| 470 | static inline uint32_t ror32(uint32_t word, unsigned int shift) |
| 471 | { |
| 472 | return (word >> (shift & 31)) | (word << (-shift & 31)); |
| 473 | } |
| 474 | |
| 475 | /** |
| 476 | * rol64 - rotate a 64-bit value left |
| 477 | * @word: value to rotate |
| 478 | * @shift: bits to roll |
| 479 | */ |
| 480 | static inline uint64_t rol64(uint64_t word, unsigned int shift) |
| 481 | { |
| 482 | return (word << (shift & 63)) | (word >> (-shift & 63)); |
| 483 | } |
| 484 | |
| 485 | /** |
| 486 | * ror64 - rotate a 64-bit value right |
| 487 | * @word: value to rotate |
| 488 | * @shift: bits to roll |
| 489 | */ |
| 490 | static inline uint64_t ror64(uint64_t word, unsigned int shift) |
| 491 | { |
| 492 | return (word >> (shift & 63)) | (word << (-shift & 63)); |
| 493 | } |
| 494 | |
| 495 | /** |
| 496 | * hswap32 - swap 16-bit halfwords within a 32-bit value |
| 497 | * @h: value to swap |
| 498 | */ |
| 499 | static inline uint32_t hswap32(uint32_t h) |
| 500 | { |
| 501 | return rol32(h, 16); |
| 502 | } |
| 503 | |
| 504 | /** |
| 505 | * hswap64 - swap 16-bit halfwords within a 64-bit value |
| 506 | * @h: value to swap |
| 507 | */ |
| 508 | static inline uint64_t hswap64(uint64_t h) |
| 509 | { |
| 510 | uint64_t m = 0x0000ffff0000ffffull; |
| 511 | h = rol64(h, 32); |
| 512 | return ((h & m) << 16) | ((h >> 16) & m); |
| 513 | } |
| 514 | |
| 515 | /** |
| 516 | * wswap64 - swap 32-bit words within a 64-bit value |
| 517 | * @h: value to swap |
| 518 | */ |
| 519 | static inline uint64_t wswap64(uint64_t h) |
| 520 | { |
| 521 | return rol64(h, 32); |
| 522 | } |
| 523 | |
| 524 | /** |
| 525 | * extract32: |
| 526 | * @value: the value to extract the bit field from |
| 527 | * @start: the lowest bit in the bit field (numbered from 0) |
| 528 | * @length: the length of the bit field |
| 529 | * |
| 530 | * Extract from the 32 bit input @value the bit field specified by the |
| 531 | * @start and @length parameters, and return it. The bit field must |
| 532 | * lie entirely within the 32 bit word. It is valid to request that |
| 533 | * all 32 bits are returned (ie @length 32 and @start 0). |
| 534 | * |
| 535 | * Returns: the value of the bit field extracted from the input value. |
| 536 | */ |
| 537 | static inline uint32_t extract32(uint32_t value, int start, int length) |
| 538 | { |
| 539 | assert(start >= 0 && length > 0 && length <= 32 - start); |
| 540 | return (value >> start) & (~0U >> (32 - length)); |
| 541 | } |
| 542 | |
| 543 | /** |
| 544 | * extract8: |
| 545 | * @value: the value to extract the bit field from |
| 546 | * @start: the lowest bit in the bit field (numbered from 0) |
| 547 | * @length: the length of the bit field |
| 548 | * |
| 549 | * Extract from the 8 bit input @value the bit field specified by the |
| 550 | * @start and @length parameters, and return it. The bit field must |
| 551 | * lie entirely within the 8 bit word. It is valid to request that |
| 552 | * all 8 bits are returned (ie @length 8 and @start 0). |
| 553 | * |
| 554 | * Returns: the value of the bit field extracted from the input value. |
| 555 | */ |
| 556 | static inline uint8_t extract8(uint8_t value, int start, int length) |
| 557 | { |
| 558 | assert(start >= 0 && length > 0 && length <= 8 - start); |
| 559 | return extract32(value, start, length); |
| 560 | } |
| 561 | |
| 562 | /** |
| 563 | * extract16: |
| 564 | * @value: the value to extract the bit field from |
| 565 | * @start: the lowest bit in the bit field (numbered from 0) |
| 566 | * @length: the length of the bit field |
| 567 | * |
| 568 | * Extract from the 16 bit input @value the bit field specified by the |
| 569 | * @start and @length parameters, and return it. The bit field must |
| 570 | * lie entirely within the 16 bit word. It is valid to request that |
| 571 | * all 16 bits are returned (ie @length 16 and @start 0). |
| 572 | * |
| 573 | * Returns: the value of the bit field extracted from the input value. |
| 574 | */ |
| 575 | static inline uint16_t extract16(uint16_t value, int start, int length) |
| 576 | { |
| 577 | assert(start >= 0 && length > 0 && length <= 16 - start); |
| 578 | return extract32(value, start, length); |
| 579 | } |
| 580 | |
| 581 | /** |
| 582 | * extract64: |
| 583 | * @value: the value to extract the bit field from |
| 584 | * @start: the lowest bit in the bit field (numbered from 0) |
| 585 | * @length: the length of the bit field |
| 586 | * |
| 587 | * Extract from the 64 bit input @value the bit field specified by the |
| 588 | * @start and @length parameters, and return it. The bit field must |
| 589 | * lie entirely within the 64 bit word. It is valid to request that |
| 590 | * all 64 bits are returned (ie @length 64 and @start 0). |
| 591 | * |
| 592 | * Returns: the value of the bit field extracted from the input value. |
| 593 | */ |
| 594 | static inline uint64_t extract64(uint64_t value, int start, int length) |
| 595 | { |
| 596 | assert(start >= 0 && length > 0 && length <= 64 - start); |
| 597 | return (value >> start) & (~0ULL >> (64 - length)); |
| 598 | } |
| 599 | |
| 600 | /** |
| 601 | * sextract32: |
| 602 | * @value: the value to extract the bit field from |
| 603 | * @start: the lowest bit in the bit field (numbered from 0) |
| 604 | * @length: the length of the bit field |
| 605 | * |
| 606 | * Extract from the 32 bit input @value the bit field specified by the |
| 607 | * @start and @length parameters, and return it, sign extended to |
| 608 | * an int32_t (ie with the most significant bit of the field propagated |
| 609 | * to all the upper bits of the return value). The bit field must lie |
| 610 | * entirely within the 32 bit word. It is valid to request that |
| 611 | * all 32 bits are returned (ie @length 32 and @start 0). |
| 612 | * |
| 613 | * Returns: the sign extended value of the bit field extracted from the |
| 614 | * input value. |
| 615 | */ |
| 616 | static inline int32_t sextract32(uint32_t value, int start, int length) |
| 617 | { |
| 618 | assert(start >= 0 && length > 0 && length <= 32 - start); |
| 619 | /* Note that this implementation relies on right shift of signed |
| 620 | * integers being an arithmetic shift. |
| 621 | */ |
| 622 | return ((int32_t)(value << (32 - length - start))) >> (32 - length); |
| 623 | } |
| 624 | |
| 625 | /** |
| 626 | * sextract64: |
| 627 | * @value: the value to extract the bit field from |
| 628 | * @start: the lowest bit in the bit field (numbered from 0) |
| 629 | * @length: the length of the bit field |
| 630 | * |
| 631 | * Extract from the 64 bit input @value the bit field specified by the |
| 632 | * @start and @length parameters, and return it, sign extended to |
| 633 | * an int64_t (ie with the most significant bit of the field propagated |
| 634 | * to all the upper bits of the return value). The bit field must lie |
| 635 | * entirely within the 64 bit word. It is valid to request that |
| 636 | * all 64 bits are returned (ie @length 64 and @start 0). |
| 637 | * |
| 638 | * Returns: the sign extended value of the bit field extracted from the |
| 639 | * input value. |
| 640 | */ |
| 641 | static inline int64_t sextract64(uint64_t value, int start, int length) |
| 642 | { |
| 643 | assert(start >= 0 && length > 0 && length <= 64 - start); |
| 644 | /* Note that this implementation relies on right shift of signed |
| 645 | * integers being an arithmetic shift. |
| 646 | */ |
| 647 | return ((int64_t)(value << (64 - length - start))) >> (64 - length); |
| 648 | } |
| 649 | |
| 650 | /** |
| 651 | * deposit32: |
| 652 | * @value: initial value to insert bit field into |
| 653 | * @start: the lowest bit in the bit field (numbered from 0) |
| 654 | * @length: the length of the bit field |
| 655 | * @fieldval: the value to insert into the bit field |
| 656 | * |
| 657 | * Deposit @fieldval into the 32 bit @value at the bit field specified |
| 658 | * by the @start and @length parameters, and return the modified |
| 659 | * @value. Bits of @value outside the bit field are not modified. |
| 660 | * Bits of @fieldval above the least significant @length bits are |
| 661 | * ignored. The bit field must lie entirely within the 32 bit word. |
| 662 | * It is valid to request that all 32 bits are modified (ie @length |
| 663 | * 32 and @start 0). |
| 664 | * |
| 665 | * Returns: the modified @value. |
| 666 | */ |
| 667 | static inline uint32_t deposit32(uint32_t value, int start, int length, |
| 668 | uint32_t fieldval) |
| 669 | { |
| 670 | uint32_t mask; |
| 671 | assert(start >= 0 && length > 0 && length <= 32 - start); |
| 672 | mask = (~0U >> (32 - length)) << start; |
| 673 | return (value & ~mask) | ((fieldval << start) & mask); |
| 674 | } |
| 675 | |
| 676 | /** |
| 677 | * deposit64: |
| 678 | * @value: initial value to insert bit field into |
| 679 | * @start: the lowest bit in the bit field (numbered from 0) |
| 680 | * @length: the length of the bit field |
| 681 | * @fieldval: the value to insert into the bit field |
| 682 | * |
| 683 | * Deposit @fieldval into the 64 bit @value at the bit field specified |
| 684 | * by the @start and @length parameters, and return the modified |
| 685 | * @value. Bits of @value outside the bit field are not modified. |
| 686 | * Bits of @fieldval above the least significant @length bits are |
| 687 | * ignored. The bit field must lie entirely within the 64 bit word. |
| 688 | * It is valid to request that all 64 bits are modified (ie @length |
| 689 | * 64 and @start 0). |
| 690 | * |
| 691 | * Returns: the modified @value. |
| 692 | */ |
| 693 | static inline uint64_t deposit64(uint64_t value, int start, int length, |
| 694 | uint64_t fieldval) |
| 695 | { |
| 696 | uint64_t mask; |
| 697 | assert(start >= 0 && length > 0 && length <= 64 - start); |
| 698 | mask = (~0ULL >> (64 - length)) << start; |
| 699 | return (value & ~mask) | ((fieldval << start) & mask); |
| 700 | } |
| 701 | |
| 702 | /** |
| 703 | * half_shuffle32: |
| 704 | * @x: 32-bit value (of which only the bottom 16 bits are of interest) |
| 705 | * |
| 706 | * Given an input value:: |
| 707 | * |
| 708 | * xxxx xxxx xxxx xxxx ABCD EFGH IJKL MNOP |
| 709 | * |
| 710 | * return the value where the bottom 16 bits are spread out into |
| 711 | * the odd bits in the word, and the even bits are zeroed:: |
| 712 | * |
| 713 | * 0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N 0O0P |
| 714 | * |
| 715 | * Any bits set in the top half of the input are ignored. |
| 716 | * |
| 717 | * Returns: the shuffled bits. |
| 718 | */ |
| 719 | static inline uint32_t half_shuffle32(uint32_t x) |
| 720 | { |
| 721 | /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits". |
| 722 | * It ignores any bits set in the top half of the input. |
| 723 | */ |
| 724 | x = ((x & 0xFF00) << 8) | (x & 0x00FF); |
| 725 | x = ((x << 4) | x) & 0x0F0F0F0F; |
| 726 | x = ((x << 2) | x) & 0x33333333; |
| 727 | x = ((x << 1) | x) & 0x55555555; |
| 728 | return x; |
| 729 | } |
| 730 | |
| 731 | /** |
| 732 | * half_shuffle64: |
| 733 | * @x: 64-bit value (of which only the bottom 32 bits are of interest) |
| 734 | * |
| 735 | * Given an input value:: |
| 736 | * |
| 737 | * xxxx xxxx xxxx .... xxxx xxxx ABCD EFGH IJKL MNOP QRST UVWX YZab cdef |
| 738 | * |
| 739 | * return the value where the bottom 32 bits are spread out into |
| 740 | * the odd bits in the word, and the even bits are zeroed:: |
| 741 | * |
| 742 | * 0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N .... 0U0V 0W0X 0Y0Z 0a0b 0c0d 0e0f |
| 743 | * |
| 744 | * Any bits set in the top half of the input are ignored. |
| 745 | * |
| 746 | * Returns: the shuffled bits. |
| 747 | */ |
| 748 | static inline uint64_t half_shuffle64(uint64_t x) |
| 749 | { |
| 750 | /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits". |
| 751 | * It ignores any bits set in the top half of the input. |
| 752 | */ |
| 753 | x = ((x & 0xFFFF0000ULL) << 16) | (x & 0xFFFF); |
| 754 | x = ((x << 8) | x) & 0x00FF00FF00FF00FFULL; |
| 755 | x = ((x << 4) | x) & 0x0F0F0F0F0F0F0F0FULL; |
| 756 | x = ((x << 2) | x) & 0x3333333333333333ULL; |
| 757 | x = ((x << 1) | x) & 0x5555555555555555ULL; |
| 758 | return x; |
| 759 | } |
| 760 | |
| 761 | /** |
| 762 | * half_unshuffle32: |
| 763 | * @x: 32-bit value (of which only the odd bits are of interest) |
| 764 | * |
| 765 | * Given an input value:: |
| 766 | * |
| 767 | * xAxB xCxD xExF xGxH xIxJ xKxL xMxN xOxP |
| 768 | * |
| 769 | * return the value where all the odd bits are compressed down |
| 770 | * into the low half of the word, and the high half is zeroed:: |
| 771 | * |
| 772 | * 0000 0000 0000 0000 ABCD EFGH IJKL MNOP |
| 773 | * |
| 774 | * Any even bits set in the input are ignored. |
| 775 | * |
| 776 | * Returns: the unshuffled bits. |
| 777 | */ |
| 778 | static inline uint32_t half_unshuffle32(uint32_t x) |
| 779 | { |
| 780 | /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits". |
| 781 | * where it is called an inverse half shuffle. |
| 782 | */ |
| 783 | x &= 0x55555555; |
| 784 | x = ((x >> 1) | x) & 0x33333333; |
| 785 | x = ((x >> 2) | x) & 0x0F0F0F0F; |
| 786 | x = ((x >> 4) | x) & 0x00FF00FF; |
| 787 | x = ((x >> 8) | x) & 0x0000FFFF; |
| 788 | return x; |
| 789 | } |
| 790 | |
| 791 | /** |
| 792 | * half_unshuffle64: |
| 793 | * @x: 64-bit value (of which only the odd bits are of interest) |
| 794 | * |
| 795 | * Given an input value:: |
| 796 | * |
| 797 | * xAxB xCxD xExF xGxH xIxJ xKxL xMxN .... xUxV xWxX xYxZ xaxb xcxd xexf |
| 798 | * |
| 799 | * return the value where all the odd bits are compressed down |
| 800 | * into the low half of the word, and the high half is zeroed:: |
| 801 | * |
| 802 | * 0000 0000 0000 .... 0000 0000 ABCD EFGH IJKL MNOP QRST UVWX YZab cdef |
| 803 | * |
| 804 | * Any even bits set in the input are ignored. |
| 805 | * |
| 806 | * Returns: the unshuffled bits. |
| 807 | */ |
| 808 | static inline uint64_t half_unshuffle64(uint64_t x) |
| 809 | { |
| 810 | /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits". |
| 811 | * where it is called an inverse half shuffle. |
| 812 | */ |
| 813 | x &= 0x5555555555555555ULL; |
| 814 | x = ((x >> 1) | x) & 0x3333333333333333ULL; |
| 815 | x = ((x >> 2) | x) & 0x0F0F0F0F0F0F0F0FULL; |
| 816 | x = ((x >> 4) | x) & 0x00FF00FF00FF00FFULL; |
| 817 | x = ((x >> 8) | x) & 0x0000FFFF0000FFFFULL; |
| 818 | x = ((x >> 16) | x) & 0x00000000FFFFFFFFULL; |
| 819 | return x; |
| 820 | } |
| 821 | |
| 822 | #endif |