xref: /qemu/include/qemu/bitops.h (revision bf8d4924) 
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 /**
28  * set_bit - Set a bit in memory
29  * @nr: the bit to set
30  * @addr: the address to start counting from
31  */
32 static inline void set_bit(long nr, unsigned long *addr)
33 {
34     unsigned long mask = BIT_MASK(nr);
35     unsigned long *p = addr + BIT_WORD(nr);
36 
37     *p  |= mask;
38 }
39 
40 /**
41  * set_bit_atomic - Set a bit in memory atomically
42  * @nr: the bit to set
43  * @addr: the address to start counting from
44  */
45 static inline void set_bit_atomic(long nr, unsigned long *addr)
46 {
47     unsigned long mask = BIT_MASK(nr);
48     unsigned long *p = addr + BIT_WORD(nr);
49 
50     atomic_or(p, mask);
51 }
52 
53 /**
54  * clear_bit - Clears a bit in memory
55  * @nr: Bit to clear
56  * @addr: Address to start counting from
57  */
58 static inline void clear_bit(long nr, unsigned long *addr)
59 {
60     unsigned long mask = BIT_MASK(nr);
61     unsigned long *p = addr + BIT_WORD(nr);
62 
63     *p &= ~mask;
64 }
65 
66 /**
67  * change_bit - Toggle a bit in memory
68  * @nr: Bit to change
69  * @addr: Address to start counting from
70  */
71 static inline void change_bit(long nr, unsigned long *addr)
72 {
73     unsigned long mask = BIT_MASK(nr);
74     unsigned long *p = addr + BIT_WORD(nr);
75 
76     *p ^= mask;
77 }
78 
79 /**
80  * test_and_set_bit - Set a bit and return its old value
81  * @nr: Bit to set
82  * @addr: Address to count from
83  */
84 static inline int test_and_set_bit(long nr, unsigned long *addr)
85 {
86     unsigned long mask = BIT_MASK(nr);
87     unsigned long *p = addr + BIT_WORD(nr);
88     unsigned long old = *p;
89 
90     *p = old | mask;
91     return (old & mask) != 0;
92 }
93 
94 /**
95  * test_and_clear_bit - Clear a bit and return its old value
96  * @nr: Bit to clear
97  * @addr: Address to count from
98  */
99 static inline int test_and_clear_bit(long nr, unsigned long *addr)
100 {
101     unsigned long mask = BIT_MASK(nr);
102     unsigned long *p = addr + BIT_WORD(nr);
103     unsigned long old = *p;
104 
105     *p = old & ~mask;
106     return (old & mask) != 0;
107 }
108 
109 /**
110  * test_and_change_bit - Change a bit and return its old value
111  * @nr: Bit to change
112  * @addr: Address to count from
113  */
114 static inline int test_and_change_bit(long nr, unsigned long *addr)
115 {
116     unsigned long mask = BIT_MASK(nr);
117     unsigned long *p = addr + BIT_WORD(nr);
118     unsigned long old = *p;
119 
120     *p = old ^ mask;
121     return (old & mask) != 0;
122 }
123 
124 /**
125  * test_bit - Determine whether a bit is set
126  * @nr: bit number to test
127  * @addr: Address to start counting from
128  */
129 static inline int test_bit(long nr, const unsigned long *addr)
130 {
131     return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
132 }
133 
134 /**
135  * find_last_bit - find the last set bit in a memory region
136  * @addr: The address to start the search at
137  * @size: The maximum size to search
138  *
139  * Returns the bit number of the first set bit, or size.
140  */
141 unsigned long find_last_bit(const unsigned long *addr,
142                             unsigned long size);
143 
144 /**
145  * find_next_bit - find the next set bit in a memory region
146  * @addr: The address to base the search on
147  * @offset: The bitnumber to start searching at
148  * @size: The bitmap size in bits
149  */
150 unsigned long find_next_bit(const unsigned long *addr,
151                             unsigned long size,
152                             unsigned long offset);
153 
154 /**
155  * find_next_zero_bit - find the next cleared bit in a memory region
156  * @addr: The address to base the search on
157  * @offset: The bitnumber to start searching at
158  * @size: The bitmap size in bits
159  */
160 
161 unsigned long find_next_zero_bit(const unsigned long *addr,
162                                  unsigned long size,
163                                  unsigned long offset);
164 
165 /**
166  * find_first_bit - find the first set bit in a memory region
167  * @addr: The address to start the search at
168  * @size: The maximum size to search
169  *
170  * Returns the bit number of the first set bit.
171  */
172 static inline unsigned long find_first_bit(const unsigned long *addr,
173                                            unsigned long size)
174 {
175     unsigned long result, tmp;
176 
177     for (result = 0; result < size; result += BITS_PER_LONG) {
178         tmp = *addr++;
179         if (tmp) {
180             result += ctzl(tmp);
181             return result < size ? result : size;
182         }
183     }
184     /* Not found */
185     return size;
186 }
187 
188 /**
189  * find_first_zero_bit - find the first cleared bit in a memory region
190  * @addr: The address to start the search at
191  * @size: The maximum size to search
192  *
193  * Returns the bit number of the first cleared bit.
194  */
195 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
196                                                 unsigned long size)
197 {
198     return find_next_zero_bit(addr, size, 0);
199 }
200 
201 static inline unsigned long hweight_long(unsigned long w)
202 {
203     unsigned long count;
204 
205     for (count = 0; w; w >>= 1) {
206         count += w & 1;
207     }
208     return count;
209 }
210 
211 /**
212  * rol8 - rotate an 8-bit value left
213  * @word: value to rotate
214  * @shift: bits to roll
215  */
216 static inline uint8_t rol8(uint8_t word, unsigned int shift)
217 {
218     return (word << shift) | (word >> (8 - shift));
219 }
220 
221 /**
222  * ror8 - rotate an 8-bit value right
223  * @word: value to rotate
224  * @shift: bits to roll
225  */
226 static inline uint8_t ror8(uint8_t word, unsigned int shift)
227 {
228     return (word >> shift) | (word << (8 - shift));
229 }
230 
231 /**
232  * rol16 - rotate a 16-bit value left
233  * @word: value to rotate
234  * @shift: bits to roll
235  */
236 static inline uint16_t rol16(uint16_t word, unsigned int shift)
237 {
238     return (word << shift) | (word >> (16 - shift));
239 }
240 
241 /**
242  * ror16 - rotate a 16-bit value right
243  * @word: value to rotate
244  * @shift: bits to roll
245  */
246 static inline uint16_t ror16(uint16_t word, unsigned int shift)
247 {
248     return (word >> shift) | (word << (16 - shift));
249 }
250 
251 /**
252  * rol32 - rotate a 32-bit value left
253  * @word: value to rotate
254  * @shift: bits to roll
255  */
256 static inline uint32_t rol32(uint32_t word, unsigned int shift)
257 {
258     return (word << shift) | (word >> (32 - shift));
259 }
260 
261 /**
262  * ror32 - rotate a 32-bit value right
263  * @word: value to rotate
264  * @shift: bits to roll
265  */
266 static inline uint32_t ror32(uint32_t word, unsigned int shift)
267 {
268     return (word >> shift) | (word << (32 - shift));
269 }
270 
271 /**
272  * rol64 - rotate a 64-bit value left
273  * @word: value to rotate
274  * @shift: bits to roll
275  */
276 static inline uint64_t rol64(uint64_t word, unsigned int shift)
277 {
278     return (word << shift) | (word >> (64 - shift));
279 }
280 
281 /**
282  * ror64 - rotate a 64-bit value right
283  * @word: value to rotate
284  * @shift: bits to roll
285  */
286 static inline uint64_t ror64(uint64_t word, unsigned int shift)
287 {
288     return (word >> shift) | (word << (64 - shift));
289 }
290 
291 /**
292  * extract32:
293  * @value: the value to extract the bit field from
294  * @start: the lowest bit in the bit field (numbered from 0)
295  * @length: the length of the bit field
296  *
297  * Extract from the 32 bit input @value the bit field specified by the
298  * @start and @length parameters, and return it. The bit field must
299  * lie entirely within the 32 bit word. It is valid to request that
300  * all 32 bits are returned (ie @length 32 and @start 0).
301  *
302  * Returns: the value of the bit field extracted from the input value.
303  */
304 static inline uint32_t extract32(uint32_t value, int start, int length)
305 {
306     assert(start >= 0 && length > 0 && length <= 32 - start);
307     return (value >> start) & (~0U >> (32 - length));
308 }
309 
310 /**
311  * extract64:
312  * @value: the value to extract the bit field from
313  * @start: the lowest bit in the bit field (numbered from 0)
314  * @length: the length of the bit field
315  *
316  * Extract from the 64 bit input @value the bit field specified by the
317  * @start and @length parameters, and return it. The bit field must
318  * lie entirely within the 64 bit word. It is valid to request that
319  * all 64 bits are returned (ie @length 64 and @start 0).
320  *
321  * Returns: the value of the bit field extracted from the input value.
322  */
323 static inline uint64_t extract64(uint64_t value, int start, int length)
324 {
325     assert(start >= 0 && length > 0 && length <= 64 - start);
326     return (value >> start) & (~0ULL >> (64 - length));
327 }
328 
329 /**
330  * sextract32:
331  * @value: the value to extract the bit field from
332  * @start: the lowest bit in the bit field (numbered from 0)
333  * @length: the length of the bit field
334  *
335  * Extract from the 32 bit input @value the bit field specified by the
336  * @start and @length parameters, and return it, sign extended to
337  * an int32_t (ie with the most significant bit of the field propagated
338  * to all the upper bits of the return value). The bit field must lie
339  * entirely within the 32 bit word. It is valid to request that
340  * all 32 bits are returned (ie @length 32 and @start 0).
341  *
342  * Returns: the sign extended value of the bit field extracted from the
343  * input value.
344  */
345 static inline int32_t sextract32(uint32_t value, int start, int length)
346 {
347     assert(start >= 0 && length > 0 && length <= 32 - start);
348     /* Note that this implementation relies on right shift of signed
349      * integers being an arithmetic shift.
350      */
351     return ((int32_t)(value << (32 - length - start))) >> (32 - length);
352 }
353 
354 /**
355  * sextract64:
356  * @value: the value to extract the bit field from
357  * @start: the lowest bit in the bit field (numbered from 0)
358  * @length: the length of the bit field
359  *
360  * Extract from the 64 bit input @value the bit field specified by the
361  * @start and @length parameters, and return it, sign extended to
362  * an int64_t (ie with the most significant bit of the field propagated
363  * to all the upper bits of the return value). The bit field must lie
364  * entirely within the 64 bit word. It is valid to request that
365  * all 64 bits are returned (ie @length 64 and @start 0).
366  *
367  * Returns: the sign extended value of the bit field extracted from the
368  * input value.
369  */
370 static inline int64_t sextract64(uint64_t value, int start, int length)
371 {
372     assert(start >= 0 && length > 0 && length <= 64 - start);
373     /* Note that this implementation relies on right shift of signed
374      * integers being an arithmetic shift.
375      */
376     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
377 }
378 
379 /**
380  * deposit32:
381  * @value: initial value to insert bit field into
382  * @start: the lowest bit in the bit field (numbered from 0)
383  * @length: the length of the bit field
384  * @fieldval: the value to insert into the bit field
385  *
386  * Deposit @fieldval into the 32 bit @value at the bit field specified
387  * by the @start and @length parameters, and return the modified
388  * @value. Bits of @value outside the bit field are not modified.
389  * Bits of @fieldval above the least significant @length bits are
390  * ignored. The bit field must lie entirely within the 32 bit word.
391  * It is valid to request that all 32 bits are modified (ie @length
392  * 32 and @start 0).
393  *
394  * Returns: the modified @value.
395  */
396 static inline uint32_t deposit32(uint32_t value, int start, int length,
397                                  uint32_t fieldval)
398 {
399     uint32_t mask;
400     assert(start >= 0 && length > 0 && length <= 32 - start);
401     mask = (~0U >> (32 - length)) << start;
402     return (value & ~mask) | ((fieldval << start) & mask);
403 }
404 
405 /**
406  * deposit64:
407  * @value: initial value to insert bit field into
408  * @start: the lowest bit in the bit field (numbered from 0)
409  * @length: the length of the bit field
410  * @fieldval: the value to insert into the bit field
411  *
412  * Deposit @fieldval into the 64 bit @value at the bit field specified
413  * by the @start and @length parameters, and return the modified
414  * @value. Bits of @value outside the bit field are not modified.
415  * Bits of @fieldval above the least significant @length bits are
416  * ignored. The bit field must lie entirely within the 64 bit word.
417  * It is valid to request that all 64 bits are modified (ie @length
418  * 64 and @start 0).
419  *
420  * Returns: the modified @value.
421  */
422 static inline uint64_t deposit64(uint64_t value, int start, int length,
423                                  uint64_t fieldval)
424 {
425     uint64_t mask;
426     assert(start >= 0 && length > 0 && length <= 64 - start);
427     mask = (~0ULL >> (64 - length)) << start;
428     return (value & ~mask) | ((fieldval << start) & mask);
429 }
430 
431 /**
432  * half_shuffle32:
433  * @value: 32-bit value (of which only the bottom 16 bits are of interest)
434  *
435  * Given an input value:
436  *  xxxx xxxx xxxx xxxx ABCD EFGH IJKL MNOP
437  * return the value where the bottom 16 bits are spread out into
438  * the odd bits in the word, and the even bits are zeroed:
439  *  0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N 0O0P
440  *
441  * Any bits set in the top half of the input are ignored.
442  *
443  * Returns: the shuffled bits.
444  */
445 static inline uint32_t half_shuffle32(uint32_t x)
446 {
447     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
448      * It ignores any bits set in the top half of the input.
449      */
450     x = ((x & 0xFF00) << 8) | (x & 0x00FF);
451     x = ((x << 4) | x) & 0x0F0F0F0F;
452     x = ((x << 2) | x) & 0x33333333;
453     x = ((x << 1) | x) & 0x55555555;
454     return x;
455 }
456 
457 /**
458  * half_shuffle64:
459  * @value: 64-bit value (of which only the bottom 32 bits are of interest)
460  *
461  * Given an input value:
462  *  xxxx xxxx xxxx .... xxxx xxxx ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
463  * return the value where the bottom 32 bits are spread out into
464  * the odd bits in the word, and the even bits are zeroed:
465  *  0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N .... 0U0V 0W0X 0Y0Z 0a0b 0c0d 0e0f
466  *
467  * Any bits set in the top half of the input are ignored.
468  *
469  * Returns: the shuffled bits.
470  */
471 static inline uint64_t half_shuffle64(uint64_t x)
472 {
473     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
474      * It ignores any bits set in the top half of the input.
475      */
476     x = ((x & 0xFFFF0000ULL) << 16) | (x & 0xFFFF);
477     x = ((x << 8) | x) & 0x00FF00FF00FF00FFULL;
478     x = ((x << 4) | x) & 0x0F0F0F0F0F0F0F0FULL;
479     x = ((x << 2) | x) & 0x3333333333333333ULL;
480     x = ((x << 1) | x) & 0x5555555555555555ULL;
481     return x;
482 }
483 
484 /**
485  * half_unshuffle32:
486  * @value: 32-bit value (of which only the odd bits are of interest)
487  *
488  * Given an input value:
489  *  xAxB xCxD xExF xGxH xIxJ xKxL xMxN xOxP
490  * return the value where all the odd bits are compressed down
491  * into the low half of the word, and the high half is zeroed:
492  *  0000 0000 0000 0000 ABCD EFGH IJKL MNOP
493  *
494  * Any even bits set in the input are ignored.
495  *
496  * Returns: the unshuffled bits.
497  */
498 static inline uint32_t half_unshuffle32(uint32_t x)
499 {
500     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
501      * where it is called an inverse half shuffle.
502      */
503     x &= 0x55555555;
504     x = ((x >> 1) | x) & 0x33333333;
505     x = ((x >> 2) | x) & 0x0F0F0F0F;
506     x = ((x >> 4) | x) & 0x00FF00FF;
507     x = ((x >> 8) | x) & 0x0000FFFF;
508     return x;
509 }
510 
511 /**
512  * half_unshuffle64:
513  * @value: 64-bit value (of which only the odd bits are of interest)
514  *
515  * Given an input value:
516  *  xAxB xCxD xExF xGxH xIxJ xKxL xMxN .... xUxV xWxX xYxZ xaxb xcxd xexf
517  * return the value where all the odd bits are compressed down
518  * into the low half of the word, and the high half is zeroed:
519  *  0000 0000 0000 .... 0000 0000 ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
520  *
521  * Any even bits set in the input are ignored.
522  *
523  * Returns: the unshuffled bits.
524  */
525 static inline uint64_t half_unshuffle64(uint64_t x)
526 {
527     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
528      * where it is called an inverse half shuffle.
529      */
530     x &= 0x5555555555555555ULL;
531     x = ((x >> 1) | x) & 0x3333333333333333ULL;
532     x = ((x >> 2) | x) & 0x0F0F0F0F0F0F0F0FULL;
533     x = ((x >> 4) | x) & 0x00FF00FF00FF00FFULL;
534     x = ((x >> 8) | x) & 0x0000FFFF0000FFFFULL;
535     x = ((x >> 16) | x) & 0x00000000FFFFFFFFULL;
536     return x;
537 }
538 
539 #endif
540