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 | unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, |
159 | const unsigned long *addr2, |
160 | const unsigned long *addr3, |
161 | unsigned long size, unsigned long n) |
162 | { |
163 | return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n); |
164 | } |
165 | EXPORT_SYMBOL(__find_nth_and_andnot_bit); |
166 | |
167 | #ifndef find_next_and_bit |
168 | unsigned long _find_next_and_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_and_bit); |
174 | #endif |
175 | |
176 | #ifndef find_next_andnot_bit |
177 | unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, |
178 | unsigned long nbits, unsigned long start) |
179 | { |
180 | return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start); |
181 | } |
182 | EXPORT_SYMBOL(_find_next_andnot_bit); |
183 | #endif |
184 | |
185 | #ifndef find_next_or_bit |
186 | unsigned long _find_next_or_bit(const unsigned long *addr1, const unsigned long *addr2, |
187 | unsigned long nbits, unsigned long start) |
188 | { |
189 | return FIND_NEXT_BIT(addr1[idx] | addr2[idx], /* nop */, nbits, start); |
190 | } |
191 | EXPORT_SYMBOL(_find_next_or_bit); |
192 | #endif |
193 | |
194 | #ifndef find_next_zero_bit |
195 | unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits, |
196 | unsigned long start) |
197 | { |
198 | return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start); |
199 | } |
200 | EXPORT_SYMBOL(_find_next_zero_bit); |
201 | #endif |
202 | |
203 | #ifndef find_last_bit |
204 | unsigned long _find_last_bit(const unsigned long *addr, unsigned long size) |
205 | { |
206 | if (size) { |
207 | unsigned long val = BITMAP_LAST_WORD_MASK(size); |
208 | unsigned long idx = (size-1) / BITS_PER_LONG; |
209 | |
210 | do { |
211 | val &= addr[idx]; |
212 | if (val) |
213 | return idx * BITS_PER_LONG + __fls(word: val); |
214 | |
215 | val = ~0ul; |
216 | } while (idx--); |
217 | } |
218 | return size; |
219 | } |
220 | EXPORT_SYMBOL(_find_last_bit); |
221 | #endif |
222 | |
223 | unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr, |
224 | unsigned long size, unsigned long offset) |
225 | { |
226 | offset = find_next_bit(addr, size, offset); |
227 | if (offset == size) |
228 | return size; |
229 | |
230 | offset = round_down(offset, 8); |
231 | *clump = bitmap_get_value8(map: addr, start: offset); |
232 | |
233 | return offset; |
234 | } |
235 | EXPORT_SYMBOL(find_next_clump8); |
236 | |
237 | #ifdef __BIG_ENDIAN |
238 | |
239 | #ifndef find_first_zero_bit_le |
240 | /* |
241 | * Find the first cleared bit in an LE memory region. |
242 | */ |
243 | unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size) |
244 | { |
245 | return FIND_FIRST_BIT(~addr[idx], swab, size); |
246 | } |
247 | EXPORT_SYMBOL(_find_first_zero_bit_le); |
248 | |
249 | #endif |
250 | |
251 | #ifndef find_next_zero_bit_le |
252 | unsigned long _find_next_zero_bit_le(const unsigned long *addr, |
253 | unsigned long size, unsigned long offset) |
254 | { |
255 | return FIND_NEXT_BIT(~addr[idx], swab, size, offset); |
256 | } |
257 | EXPORT_SYMBOL(_find_next_zero_bit_le); |
258 | #endif |
259 | |
260 | #ifndef find_next_bit_le |
261 | unsigned long _find_next_bit_le(const unsigned long *addr, |
262 | unsigned long size, unsigned long offset) |
263 | { |
264 | return FIND_NEXT_BIT(addr[idx], swab, size, offset); |
265 | } |
266 | EXPORT_SYMBOL(_find_next_bit_le); |
267 | |
268 | #endif |
269 | |
270 | #endif /* __BIG_ENDIAN */ |
271 | |