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 = idx * BITS_PER_LONG + fns(tmp, nr); \
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 /*
120 * Find the first set bit in three memory regions.
121 */
122 unsigned long _find_first_and_and_bit(const unsigned long *addr1,
123 const unsigned long *addr2,
124 const unsigned long *addr3,
125 unsigned long size)
126 {
127 return FIND_FIRST_BIT(addr1[idx] & addr2[idx] & addr3[idx], /* nop */, size);
128 }
129 EXPORT_SYMBOL(_find_first_and_and_bit);
130
131 #ifndef find_first_zero_bit
132 /*
133 * Find the first cleared bit in a memory region.
134 */
135 unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
136 {
137 return FIND_FIRST_BIT(~addr[idx], /* nop */, size);
138 }
139 EXPORT_SYMBOL(_find_first_zero_bit);
140 #endif
141
142 #ifndef find_next_bit
143 unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
144 {
145 return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
146 }
147 EXPORT_SYMBOL(_find_next_bit);
148 #endif
149
150 unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n)
151 {
152 return FIND_NTH_BIT(addr[idx], size, n);
153 }
154 EXPORT_SYMBOL(__find_nth_bit);
155
156 unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2,
157 unsigned long size, unsigned long n)
158 {
159 return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n);
160 }
161 EXPORT_SYMBOL(__find_nth_and_bit);
162
163 unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
164 unsigned long size, unsigned long n)
165 {
166 return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n);
167 }
168 EXPORT_SYMBOL(__find_nth_andnot_bit);
169
170 unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1,
171 const unsigned long *addr2,
172 const unsigned long *addr3,
173 unsigned long size, unsigned long n)
174 {
175 return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n);
176 }
177 EXPORT_SYMBOL(__find_nth_and_andnot_bit);
178
179 #ifndef find_next_and_bit
180 unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,
181 unsigned long nbits, unsigned long start)
182 {
183 return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);
184 }
185 EXPORT_SYMBOL(_find_next_and_bit);
186 #endif
187
188 #ifndef find_next_andnot_bit
189 unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
190 unsigned long nbits, unsigned long start)
191 {
192 return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start);
193 }
194 EXPORT_SYMBOL(_find_next_andnot_bit);
195 #endif
196
197 #ifndef find_next_or_bit
198 unsigned long _find_next_or_bit(const unsigned long *addr1, const unsigned long *addr2,
199 unsigned long nbits, unsigned long start)
200 {
201 return FIND_NEXT_BIT(addr1[idx] | addr2[idx], /* nop */, nbits, start);
202 }
203 EXPORT_SYMBOL(_find_next_or_bit);
204 #endif
205
206 #ifndef find_next_zero_bit
207 unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
208 unsigned long start)
209 {
210 return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
211 }
212 EXPORT_SYMBOL(_find_next_zero_bit);
213 #endif
214
215 #ifndef find_last_bit
216 unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
217 {
218 if (size) {
219 unsigned long val = BITMAP_LAST_WORD_MASK(size);
220 unsigned long idx = (size-1) / BITS_PER_LONG;
221
222 do {
223 val &= addr[idx];
224 if (val)
225 return idx * BITS_PER_LONG + __fls(val);
226
227 val = ~0ul;
228 } while (idx--);
229 }
230 return size;
231 }
232 EXPORT_SYMBOL(_find_last_bit);
233 #endif
234
235 unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
236 unsigned long size, unsigned long offset)
237 {
238 offset = find_next_bit(addr, size, offset);
239 if (offset == size)
240 return size;
241
242 offset = round_down(offset, 8);
243 *clump = bitmap_get_value8(addr, offset);
244
245 return offset;
246 }
247 EXPORT_SYMBOL(find_next_clump8);
248
249 #ifdef __BIG_ENDIAN
250
251 #ifndef find_first_zero_bit_le
252 /*
253 * Find the first cleared bit in an LE memory region.
254 */
255 unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size)
256 {
257 return FIND_FIRST_BIT(~addr[idx], swab, size);
258 }
259 EXPORT_SYMBOL(_find_first_zero_bit_le);
260
261 #endif
262
263 #ifndef find_next_zero_bit_le
264 unsigned long _find_next_zero_bit_le(const unsigned long *addr,
265 unsigned long size, unsigned long offset)
266 {
267 return FIND_NEXT_BIT(~addr[idx], swab, size, offset);
268 }
269 EXPORT_SYMBOL(_find_next_zero_bit_le);
270 #endif
271
272 #ifndef find_next_bit_le
273 unsigned long _find_next_bit_le(const unsigned long *addr,
274 unsigned long size, unsigned long offset)
275 {
276 return FIND_NEXT_BIT(addr[idx], swab, size, offset);
277 }
278 EXPORT_SYMBOL(_find_next_bit_le);
279
280 #endif
281
282 #endif /* __BIG_ENDIAN */
283
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