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_zero_bit 186 unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits, 187 unsigned long start) 188 { 189 return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start); 190 } 191 EXPORT_SYMBOL(_find_next_zero_bit); 192 #endif 193 194 #ifndef find_last_bit 195 unsigned long _find_last_bit(const unsigned long *addr, unsigned long size) 196 { 197 if (size) { 198 unsigned long val = BITMAP_LAST_WORD_MASK(size); 199 unsigned long idx = (size-1) / BITS_PER_LONG; 200 201 do { 202 val &= addr[idx]; 203 if (val) 204 return idx * BITS_PER_LONG + __fls(val); 205 206 val = ~0ul; 207 } while (idx--); 208 } 209 return size; 210 } 211 EXPORT_SYMBOL(_find_last_bit); 212 #endif 213 214 unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr, 215 unsigned long size, unsigned long offset) 216 { 217 offset = find_next_bit(addr, size, offset); 218 if (offset == size) 219 return size; 220 221 offset = round_down(offset, 8); 222 *clump = bitmap_get_value8(addr, offset); 223 224 return offset; 225 } 226 EXPORT_SYMBOL(find_next_clump8); 227 228 #ifdef __BIG_ENDIAN 229 230 #ifndef find_first_zero_bit_le 231 /* 232 * Find the first cleared bit in an LE memory region. 233 */ 234 unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size) 235 { 236 return FIND_FIRST_BIT(~addr[idx], swab, size); 237 } 238 EXPORT_SYMBOL(_find_first_zero_bit_le); 239 240 #endif 241 242 #ifndef find_next_zero_bit_le 243 unsigned long _find_next_zero_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_zero_bit_le); 249 #endif 250 251 #ifndef find_next_bit_le 252 unsigned long _find_next_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_bit_le); 258 259 #endif 260 261 #endif /* __BIG_ENDIAN */ 262