xref: /qemu/include/qemu/bitops.h (revision 6402cbbb) 
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 /**
205  * rol8 - rotate an 8-bit value left
206  * @word: value to rotate
207  * @shift: bits to roll
208  */
209 static 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  */
219 static 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  */
229 static 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  */
239 static 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  */
249 static 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  */
259 static 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  */
269 static 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  */
279 static 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  */
297 static 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  */
316 static 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  */
338 static 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  */
363 static 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  */
389 static 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  */
415 static 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  */
438 static 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  */
464 static 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  */
491 static 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  */
518 static 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