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 */
35static 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 */
48static 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 */
61static 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 */
74static 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 */
87static 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 */
102static 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 */
117static 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 */
132static 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 */
144unsigned 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 */
153unsigned 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
164unsigned 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 */
175static 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 */
198static 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/**
205 * rol8 - rotate an 8-bit value left
206 * @word: value to rotate
207 * @shift: bits to roll
208 */
209static inline uint8_t rol8(uint8_t word, unsigned int shift)
210{
211 return (word << shift) | (word >> ((8 - shift) & 7));
212}
213
214/**
215 * ror8 - rotate an 8-bit value right
216 * @word: value to rotate
217 * @shift: bits to roll
218 */
219static inline uint8_t ror8(uint8_t word, unsigned int shift)
220{
221 return (word >> shift) | (word << ((8 - shift) & 7));
222}
223
224/**
225 * rol16 - rotate a 16-bit value left
226 * @word: value to rotate
227 * @shift: bits to roll
228 */
229static inline uint16_t rol16(uint16_t word, unsigned int shift)
230{
231 return (word << shift) | (word >> ((16 - shift) & 15));
232}
233
234/**
235 * ror16 - rotate a 16-bit value right
236 * @word: value to rotate
237 * @shift: bits to roll
238 */
239static inline uint16_t ror16(uint16_t word, unsigned int shift)
240{
241 return (word >> shift) | (word << ((16 - shift) & 15));
242}
243
244/**
245 * rol32 - rotate a 32-bit value left
246 * @word: value to rotate
247 * @shift: bits to roll
248 */
249static inline uint32_t rol32(uint32_t word, unsigned int shift)
250{
251 return (word << shift) | (word >> ((32 - shift) & 31));
252}
253
254/**
255 * ror32 - rotate a 32-bit value right
256 * @word: value to rotate
257 * @shift: bits to roll
258 */
259static inline uint32_t ror32(uint32_t word, unsigned int shift)
260{
261 return (word >> shift) | (word << ((32 - shift) & 31));
262}
263
264/**
265 * rol64 - rotate a 64-bit value left
266 * @word: value to rotate
267 * @shift: bits to roll
268 */
269static inline uint64_t rol64(uint64_t word, unsigned int shift)
270{
271 return (word << shift) | (word >> ((64 - shift) & 63));
272}
273
274/**
275 * ror64 - rotate a 64-bit value right
276 * @word: value to rotate
277 * @shift: bits to roll
278 */
279static inline uint64_t ror64(uint64_t word, unsigned int shift)
280{
281 return (word >> shift) | (word << ((64 - shift) & 63));
282}
283
284/**
285 * extract32:
286 * @value: the value to extract the bit field from
287 * @start: the lowest bit in the bit field (numbered from 0)
288 * @length: the length of the bit field
289 *
290 * Extract from the 32 bit input @value the bit field specified by the
291 * @start and @length parameters, and return it. The bit field must
292 * lie entirely within the 32 bit word. It is valid to request that
293 * all 32 bits are returned (ie @length 32 and @start 0).
294 *
295 * Returns: the value of the bit field extracted from the input value.
296 */
297static inline uint32_t extract32(uint32_t value, int start, int length)
298{
299 assert(start >= 0 && length > 0 && length <= 32 - start);
300 return (value >> start) & (~0U >> (32 - length));
301}
302
303/**
304 * extract64:
305 * @value: the value to extract the bit field from
306 * @start: the lowest bit in the bit field (numbered from 0)
307 * @length: the length of the bit field
308 *
309 * Extract from the 64 bit input @value the bit field specified by the
310 * @start and @length parameters, and return it. The bit field must
311 * lie entirely within the 64 bit word. It is valid to request that
312 * all 64 bits are returned (ie @length 64 and @start 0).
313 *
314 * Returns: the value of the bit field extracted from the input value.
315 */
316static inline uint64_t extract64(uint64_t value, int start, int length)
317{
318 assert(start >= 0 && length > 0 && length <= 64 - start);
319 return (value >> start) & (~0ULL >> (64 - length));
320}
321
322/**
323 * sextract32:
324 * @value: the value to extract the bit field from
325 * @start: the lowest bit in the bit field (numbered from 0)
326 * @length: the length of the bit field
327 *
328 * Extract from the 32 bit input @value the bit field specified by the
329 * @start and @length parameters, and return it, sign extended to
330 * an int32_t (ie with the most significant bit of the field propagated
331 * to all the upper bits of the return value). The bit field must lie
332 * entirely within the 32 bit word. It is valid to request that
333 * all 32 bits are returned (ie @length 32 and @start 0).
334 *
335 * Returns: the sign extended value of the bit field extracted from the
336 * input value.
337 */
338static inline int32_t sextract32(uint32_t value, int start, int length)
339{
340 assert(start >= 0 && length > 0 && length <= 32 - start);
341 /* Note that this implementation relies on right shift of signed
342 * integers being an arithmetic shift.
343 */
344 return ((int32_t)(value << (32 - length - start))) >> (32 - length);
345}
346
347/**
348 * sextract64:
349 * @value: the value to extract the bit field from
350 * @start: the lowest bit in the bit field (numbered from 0)
351 * @length: the length of the bit field
352 *
353 * Extract from the 64 bit input @value the bit field specified by the
354 * @start and @length parameters, and return it, sign extended to
355 * an int64_t (ie with the most significant bit of the field propagated
356 * to all the upper bits of the return value). The bit field must lie
357 * entirely within the 64 bit word. It is valid to request that
358 * all 64 bits are returned (ie @length 64 and @start 0).
359 *
360 * Returns: the sign extended value of the bit field extracted from the
361 * input value.
362 */
363static inline int64_t sextract64(uint64_t value, int start, int length)
364{
365 assert(start >= 0 && length > 0 && length <= 64 - start);
366 /* Note that this implementation relies on right shift of signed
367 * integers being an arithmetic shift.
368 */
369 return ((int64_t)(value << (64 - length - start))) >> (64 - length);
370}
371
372/**
373 * deposit32:
374 * @value: initial value to insert bit field into
375 * @start: the lowest bit in the bit field (numbered from 0)
376 * @length: the length of the bit field
377 * @fieldval: the value to insert into the bit field
378 *
379 * Deposit @fieldval into the 32 bit @value at the bit field specified
380 * by the @start and @length parameters, and return the modified
381 * @value. Bits of @value outside the bit field are not modified.
382 * Bits of @fieldval above the least significant @length bits are
383 * ignored. The bit field must lie entirely within the 32 bit word.
384 * It is valid to request that all 32 bits are modified (ie @length
385 * 32 and @start 0).
386 *
387 * Returns: the modified @value.
388 */
389static inline uint32_t deposit32(uint32_t value, int start, int length,
390 uint32_t fieldval)
391{
392 uint32_t mask;
393 assert(start >= 0 && length > 0 && length <= 32 - start);
394 mask = (~0U >> (32 - length)) << start;
395 return (value & ~mask) | ((fieldval << start) & mask);
396}
397
398/**
399 * deposit64:
400 * @value: initial value to insert bit field into
401 * @start: the lowest bit in the bit field (numbered from 0)
402 * @length: the length of the bit field
403 * @fieldval: the value to insert into the bit field
404 *
405 * Deposit @fieldval into the 64 bit @value at the bit field specified
406 * by the @start and @length parameters, and return the modified
407 * @value. Bits of @value outside the bit field are not modified.
408 * Bits of @fieldval above the least significant @length bits are
409 * ignored. The bit field must lie entirely within the 64 bit word.
410 * It is valid to request that all 64 bits are modified (ie @length
411 * 64 and @start 0).
412 *
413 * Returns: the modified @value.
414 */
415static inline uint64_t deposit64(uint64_t value, int start, int length,
416 uint64_t fieldval)
417{
418 uint64_t mask;
419 assert(start >= 0 && length > 0 && length <= 64 - start);
420 mask = (~0ULL >> (64 - length)) << start;
421 return (value & ~mask) | ((fieldval << start) & mask);
422}
423
424/**
425 * half_shuffle32:
426 * @value: 32-bit value (of which only the bottom 16 bits are of interest)
427 *
428 * Given an input value:
429 * xxxx xxxx xxxx xxxx ABCD EFGH IJKL MNOP
430 * return the value where the bottom 16 bits are spread out into
431 * the odd bits in the word, and the even bits are zeroed:
432 * 0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N 0O0P
433 *
434 * Any bits set in the top half of the input are ignored.
435 *
436 * Returns: the shuffled bits.
437 */
438static inline uint32_t half_shuffle32(uint32_t x)
439{
440 /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
441 * It ignores any bits set in the top half of the input.
442 */
443 x = ((x & 0xFF00) << 8) | (x & 0x00FF);
444 x = ((x << 4) | x) & 0x0F0F0F0F;
445 x = ((x << 2) | x) & 0x33333333;
446 x = ((x << 1) | x) & 0x55555555;
447 return x;
448}
449
450/**
451 * half_shuffle64:
452 * @value: 64-bit value (of which only the bottom 32 bits are of interest)
453 *
454 * Given an input value:
455 * xxxx xxxx xxxx .... xxxx xxxx ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
456 * return the value where the bottom 32 bits are spread out into
457 * the odd bits in the word, and the even bits are zeroed:
458 * 0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N .... 0U0V 0W0X 0Y0Z 0a0b 0c0d 0e0f
459 *
460 * Any bits set in the top half of the input are ignored.
461 *
462 * Returns: the shuffled bits.
463 */
464static inline uint64_t half_shuffle64(uint64_t x)
465{
466 /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
467 * It ignores any bits set in the top half of the input.
468 */
469 x = ((x & 0xFFFF0000ULL) << 16) | (x & 0xFFFF);
470 x = ((x << 8) | x) & 0x00FF00FF00FF00FFULL;
471 x = ((x << 4) | x) & 0x0F0F0F0F0F0F0F0FULL;
472 x = ((x << 2) | x) & 0x3333333333333333ULL;
473 x = ((x << 1) | x) & 0x5555555555555555ULL;
474 return x;
475}
476
477/**
478 * half_unshuffle32:
479 * @value: 32-bit value (of which only the odd bits are of interest)
480 *
481 * Given an input value:
482 * xAxB xCxD xExF xGxH xIxJ xKxL xMxN xOxP
483 * return the value where all the odd bits are compressed down
484 * into the low half of the word, and the high half is zeroed:
485 * 0000 0000 0000 0000 ABCD EFGH IJKL MNOP
486 *
487 * Any even bits set in the input are ignored.
488 *
489 * Returns: the unshuffled bits.
490 */
491static inline uint32_t half_unshuffle32(uint32_t x)
492{
493 /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
494 * where it is called an inverse half shuffle.
495 */
496 x &= 0x55555555;
497 x = ((x >> 1) | x) & 0x33333333;
498 x = ((x >> 2) | x) & 0x0F0F0F0F;
499 x = ((x >> 4) | x) & 0x00FF00FF;
500 x = ((x >> 8) | x) & 0x0000FFFF;
501 return x;
502}
503
504/**
505 * half_unshuffle64:
506 * @value: 64-bit value (of which only the odd bits are of interest)
507 *
508 * Given an input value:
509 * xAxB xCxD xExF xGxH xIxJ xKxL xMxN .... xUxV xWxX xYxZ xaxb xcxd xexf
510 * return the value where all the odd bits are compressed down
511 * into the low half of the word, and the high half is zeroed:
512 * 0000 0000 0000 .... 0000 0000 ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
513 *
514 * Any even bits set in the input are ignored.
515 *
516 * Returns: the unshuffled bits.
517 */
518static inline uint64_t half_unshuffle64(uint64_t x)
519{
520 /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
521 * where it is called an inverse half shuffle.
522 */
523 x &= 0x5555555555555555ULL;
524 x = ((x >> 1) | x) & 0x3333333333333333ULL;
525 x = ((x >> 2) | x) & 0x0F0F0F0F0F0F0F0FULL;
526 x = ((x >> 4) | x) & 0x00FF00FF00FF00FFULL;
527 x = ((x >> 8) | x) & 0x0000FFFF0000FFFFULL;
528 x = ((x >> 16) | x) & 0x00000000FFFFFFFFULL;
529 return x;
530}
531
532#endif
533