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 bit set in 1st memory region and unset in 2nd. 121 */ 122 unsigned long _find_first_andnot_bit(const unsigned long *addr1, 123 const unsigned long *addr2, 124 unsigned long size) 125 { 126 return FIND_FIRST_BIT(addr1[idx] & ~addr2[idx], /* nop */, size); 127 } 128 EXPORT_SYMBOL(_find_first_andnot_bit); 129 130 /* 131 * Find the first set bit in three memory regions. 132 */ 133 unsigned long _find_first_and_and_bit(const unsigned long *addr1, 134 const unsigned long *addr2, 135 const unsigned long *addr3, 136 unsigned long size) 137 { 138 return FIND_FIRST_BIT(addr1[idx] & addr2[idx] & addr3[idx], /* nop */, size); 139 } 140 EXPORT_SYMBOL(_find_first_and_and_bit); 141 142 #ifndef find_first_zero_bit 143 /* 144 * Find the first cleared bit in a memory region. 145 */ 146 unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size) 147 { 148 return FIND_FIRST_BIT(~addr[idx], /* nop */, size); 149 } 150 EXPORT_SYMBOL(_find_first_zero_bit); 151 #endif 152 153 #ifndef find_next_bit 154 unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start) 155 { 156 return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start); 157 } 158 EXPORT_SYMBOL(_find_next_bit); 159 #endif 160 161 unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n) 162 { 163 return FIND_NTH_BIT(addr[idx], size, n); 164 } 165 EXPORT_SYMBOL(__find_nth_bit); 166 167 unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2, 168 unsigned long size, unsigned long n) 169 { 170 return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n); 171 } 172 EXPORT_SYMBOL(__find_nth_and_bit); 173 174 unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, 175 unsigned long size, unsigned long n) 176 { 177 return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n); 178 } 179 EXPORT_SYMBOL(__find_nth_andnot_bit); 180 181 unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, 182 const unsigned long *addr2, 183 const unsigned long *addr3, 184 unsigned long size, unsigned long n) 185 { 186 return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n); 187 } 188 EXPORT_SYMBOL(__find_nth_and_andnot_bit); 189 190 #ifndef find_next_and_bit 191 unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2, 192 unsigned long nbits, unsigned long start) 193 { 194 return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start); 195 } 196 EXPORT_SYMBOL(_find_next_and_bit); 197 #endif 198 199 #ifndef find_next_andnot_bit 200 unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, 201 unsigned long nbits, unsigned long start) 202 { 203 return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start); 204 } 205 EXPORT_SYMBOL(_find_next_andnot_bit); 206 #endif 207 208 #ifndef find_next_or_bit 209 unsigned long _find_next_or_bit(const unsigned long *addr1, const unsigned long *addr2, 210 unsigned long nbits, unsigned long start) 211 { 212 return FIND_NEXT_BIT(addr1[idx] | addr2[idx], /* nop */, nbits, start); 213 } 214 EXPORT_SYMBOL(_find_next_or_bit); 215 #endif 216 217 #ifndef find_next_zero_bit 218 unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits, 219 unsigned long start) 220 { 221 return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start); 222 } 223 EXPORT_SYMBOL(_find_next_zero_bit); 224 #endif 225 226 #ifndef find_last_bit 227 unsigned long _find_last_bit(const unsigned long *addr, unsigned long size) 228 { 229 if (size) { 230 unsigned long val = BITMAP_LAST_WORD_MASK(size); 231 unsigned long idx = (size-1) / BITS_PER_LONG; 232 233 do { 234 val &= addr[idx]; 235 if (val) 236 return idx * BITS_PER_LONG + __fls(val); 237 238 val = ~0ul; 239 } while (idx--); 240 } 241 return size; 242 } 243 EXPORT_SYMBOL(_find_last_bit); 244 #endif 245 246 unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr, 247 unsigned long size, unsigned long offset) 248 { 249 offset = find_next_bit(addr, size, offset); 250 if (offset == size) 251 return size; 252 253 offset = round_down(offset, 8); 254 *clump = bitmap_get_value8(addr, offset); 255 256 return offset; 257 } 258 EXPORT_SYMBOL(find_next_clump8); 259 260 #ifdef __BIG_ENDIAN 261 262 #ifndef find_first_zero_bit_le 263 /* 264 * Find the first cleared bit in an LE memory region. 265 */ 266 unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size) 267 { 268 return FIND_FIRST_BIT(~addr[idx], swab, size); 269 } 270 EXPORT_SYMBOL(_find_first_zero_bit_le); 271 272 #endif 273 274 #ifndef find_next_zero_bit_le 275 unsigned long _find_next_zero_bit_le(const unsigned long *addr, 276 unsigned long size, unsigned long offset) 277 { 278 return FIND_NEXT_BIT(~addr[idx], swab, size, offset); 279 } 280 EXPORT_SYMBOL(_find_next_zero_bit_le); 281 #endif 282 283 #ifndef find_next_bit_le 284 unsigned long _find_next_bit_le(const unsigned long *addr, 285 unsigned long size, unsigned long offset) 286 { 287 return FIND_NEXT_BIT(addr[idx], swab, size, offset); 288 } 289 EXPORT_SYMBOL(_find_next_bit_le); 290 291 #endif 292 293 #endif /* __BIG_ENDIAN */ 294