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 /* 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