Merge tag 'mm-stable-2022-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git...
[platform/kernel/linux-starfive.git] / lib / find_bit.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* bit search implementation
3  *
4  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  *
7  * Copyright (C) 2008 IBM Corporation
8  * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
9  * (Inspired by David Howell's find_next_bit implementation)
10  *
11  * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
12  * size and improve performance, 2015.
13  */
14
15 #include <linux/bitops.h>
16 #include <linux/bitmap.h>
17 #include <linux/export.h>
18 #include <linux/math.h>
19 #include <linux/minmax.h>
20 #include <linux/swab.h>
21
22 /*
23  * Common helper for find_bit() function family
24  * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
25  * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
26  * @size: The bitmap size in bits
27  */
28 #define FIND_FIRST_BIT(FETCH, MUNGE, size)                                      \
29 ({                                                                              \
30         unsigned long idx, val, sz = (size);                                    \
31                                                                                 \
32         for (idx = 0; idx * BITS_PER_LONG < sz; idx++) {                        \
33                 val = (FETCH);                                                  \
34                 if (val) {                                                      \
35                         sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz);  \
36                         break;                                                  \
37                 }                                                               \
38         }                                                                       \
39                                                                                 \
40         sz;                                                                     \
41 })
42
43 /*
44  * Common helper for find_next_bit() function family
45  * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
46  * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
47  * @size: The bitmap size in bits
48  * @start: The bitnumber to start searching at
49  */
50 #define FIND_NEXT_BIT(FETCH, MUNGE, size, start)                                \
51 ({                                                                              \
52         unsigned long mask, idx, tmp, sz = (size), __start = (start);           \
53                                                                                 \
54         if (unlikely(__start >= sz))                                            \
55                 goto out;                                                       \
56                                                                                 \
57         mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start));                          \
58         idx = __start / BITS_PER_LONG;                                          \
59                                                                                 \
60         for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) {                       \
61                 if ((idx + 1) * BITS_PER_LONG >= sz)                            \
62                         goto out;                                               \
63                 idx++;                                                          \
64         }                                                                       \
65                                                                                 \
66         sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz);                  \
67 out:                                                                            \
68         sz;                                                                     \
69 })
70
71 #define FIND_NTH_BIT(FETCH, size, num)                                          \
72 ({                                                                              \
73         unsigned long sz = (size), nr = (num), idx, w, tmp;                     \
74                                                                                 \
75         for (idx = 0; (idx + 1) * BITS_PER_LONG <= sz; idx++) {                 \
76                 if (idx * BITS_PER_LONG + nr >= sz)                             \
77                         goto out;                                               \
78                                                                                 \
79                 tmp = (FETCH);                                                  \
80                 w = hweight_long(tmp);                                          \
81                 if (w > nr)                                                     \
82                         goto found;                                             \
83                                                                                 \
84                 nr -= w;                                                        \
85         }                                                                       \
86                                                                                 \
87         if (sz % BITS_PER_LONG)                                                 \
88                 tmp = (FETCH) & BITMAP_LAST_WORD_MASK(sz);                      \
89 found:                                                                          \
90         sz = min(idx * BITS_PER_LONG + fns(tmp, nr), sz);                       \
91 out:                                                                            \
92         sz;                                                                     \
93 })
94
95 #ifndef find_first_bit
96 /*
97  * Find the first set bit in a memory region.
98  */
99 unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
100 {
101         return FIND_FIRST_BIT(addr[idx], /* nop */, size);
102 }
103 EXPORT_SYMBOL(_find_first_bit);
104 #endif
105
106 #ifndef find_first_and_bit
107 /*
108  * Find the first set bit in two memory regions.
109  */
110 unsigned long _find_first_and_bit(const unsigned long *addr1,
111                                   const unsigned long *addr2,
112                                   unsigned long size)
113 {
114         return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size);
115 }
116 EXPORT_SYMBOL(_find_first_and_bit);
117 #endif
118
119 #ifndef find_first_zero_bit
120 /*
121  * Find the first cleared bit in a memory region.
122  */
123 unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
124 {
125         return FIND_FIRST_BIT(~addr[idx], /* nop */, size);
126 }
127 EXPORT_SYMBOL(_find_first_zero_bit);
128 #endif
129
130 #ifndef find_next_bit
131 unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
132 {
133         return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
134 }
135 EXPORT_SYMBOL(_find_next_bit);
136 #endif
137
138 unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n)
139 {
140         return FIND_NTH_BIT(addr[idx], size, n);
141 }
142 EXPORT_SYMBOL(__find_nth_bit);
143
144 unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2,
145                                  unsigned long size, unsigned long n)
146 {
147         return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n);
148 }
149 EXPORT_SYMBOL(__find_nth_and_bit);
150
151 unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
152                                  unsigned long size, unsigned long n)
153 {
154         return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n);
155 }
156 EXPORT_SYMBOL(__find_nth_andnot_bit);
157
158 #ifndef find_next_and_bit
159 unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,
160                                         unsigned long nbits, unsigned long start)
161 {
162         return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);
163 }
164 EXPORT_SYMBOL(_find_next_and_bit);
165 #endif
166
167 #ifndef find_next_andnot_bit
168 unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
169                                         unsigned long nbits, unsigned long start)
170 {
171         return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start);
172 }
173 EXPORT_SYMBOL(_find_next_andnot_bit);
174 #endif
175
176 #ifndef find_next_zero_bit
177 unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
178                                          unsigned long start)
179 {
180         return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
181 }
182 EXPORT_SYMBOL(_find_next_zero_bit);
183 #endif
184
185 #ifndef find_last_bit
186 unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
187 {
188         if (size) {
189                 unsigned long val = BITMAP_LAST_WORD_MASK(size);
190                 unsigned long idx = (size-1) / BITS_PER_LONG;
191
192                 do {
193                         val &= addr[idx];
194                         if (val)
195                                 return idx * BITS_PER_LONG + __fls(val);
196
197                         val = ~0ul;
198                 } while (idx--);
199         }
200         return size;
201 }
202 EXPORT_SYMBOL(_find_last_bit);
203 #endif
204
205 unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
206                                unsigned long size, unsigned long offset)
207 {
208         offset = find_next_bit(addr, size, offset);
209         if (offset == size)
210                 return size;
211
212         offset = round_down(offset, 8);
213         *clump = bitmap_get_value8(addr, offset);
214
215         return offset;
216 }
217 EXPORT_SYMBOL(find_next_clump8);
218
219 #ifdef __BIG_ENDIAN
220
221 #ifndef find_first_zero_bit_le
222 /*
223  * Find the first cleared bit in an LE memory region.
224  */
225 unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size)
226 {
227         return FIND_FIRST_BIT(~addr[idx], swab, size);
228 }
229 EXPORT_SYMBOL(_find_first_zero_bit_le);
230
231 #endif
232
233 #ifndef find_next_zero_bit_le
234 unsigned long _find_next_zero_bit_le(const unsigned long *addr,
235                                         unsigned long size, unsigned long offset)
236 {
237         return FIND_NEXT_BIT(~addr[idx], swab, size, offset);
238 }
239 EXPORT_SYMBOL(_find_next_zero_bit_le);
240 #endif
241
242 #ifndef find_next_bit_le
243 unsigned long _find_next_bit_le(const unsigned long *addr,
244                                 unsigned long size, unsigned long offset)
245 {
246         return FIND_NEXT_BIT(addr[idx], swab, size, offset);
247 }
248 EXPORT_SYMBOL(_find_next_bit_le);
249
250 #endif
251
252 #endif /* __BIG_ENDIAN */