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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 | // SPDX-License-Identifier: GPL-2.0-or-later /* bit search implementation * * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * Copyright (C) 2008 IBM Corporation * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au> * (Inspired by David Howell's find_next_bit implementation) * * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease * size and improve performance, 2015. */ #include <asm/byteorder.h> #include <linux/bitops.h> #include <linux/bitmap.h> #include <linux/export.h> /* * Common helper for find_bit() function family * @FETCH: The expression that fetches and pre-processes each word of bitmap(s) * @MUNGE: The expression that post-processes a word containing found bit (may be empty) * @size: The bitmap size in bits */ #define FIND_FIRST_BIT(FETCH, MUNGE, size) \ ({ \ unsigned long idx, val, sz = (size); \ \ for (idx = 0; idx * BITS_PER_LONG < sz; idx++) { \ val = (FETCH); \ if (val) { \ sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz); \ break; \ } \ } \ \ sz; \ }) /* * Common helper for find_next_bit() function family * @FETCH: The expression that fetches and pre-processes each word of bitmap(s) * @MUNGE: The expression that post-processes a word containing found bit (may be empty) * @size: The bitmap size in bits * @start: The bitnumber to start searching at */ #define FIND_NEXT_BIT(FETCH, MUNGE, size, start) \ ({ \ unsigned long mask, idx, tmp, sz = (size), __start = (start); \ \ if (unlikely(__start >= sz)) \ goto out; \ \ mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start)); \ idx = __start / BITS_PER_LONG; \ \ for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) { \ if ((idx + 1) * BITS_PER_LONG >= sz) \ goto out; \ idx++; \ } \ \ sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz); \ out: \ sz; \ }) #ifndef find_first_bit /* * Find the first set bit in a memory region. */ unsigned long _find_first_bit(const unsigned long *addr, unsigned long size) { return FIND_FIRST_BIT(addr[idx], /* nop */, size); } EXPORT_SYMBOL(_find_first_bit); #endif #ifndef find_first_zero_bit /* * Find the first cleared bit in a memory region. */ unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size) { return FIND_FIRST_BIT(~addr[idx], /* nop */, size); } EXPORT_SYMBOL(_find_first_zero_bit); #endif #ifndef find_next_bit unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start) { return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start); } EXPORT_SYMBOL(_find_next_bit); #endif #ifndef find_next_zero_bit unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits, unsigned long start) { return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start); } EXPORT_SYMBOL(_find_next_zero_bit); #endif #ifndef find_last_bit unsigned long _find_last_bit(const unsigned long *addr, unsigned long size) { if (size) { unsigned long val = BITMAP_LAST_WORD_MASK(size); unsigned long idx = (size-1) / BITS_PER_LONG; do { val &= addr[idx]; if (val) return idx * BITS_PER_LONG + __fls(val); val = ~0ul; } while (idx--); } return size; } EXPORT_SYMBOL(_find_last_bit); #endif /* * Wrapper functions matching sandbox's asm/bitops.h declarations. * These provide the expected function signatures for sandbox platform. */ int find_first_zero_bit(void *addr, unsigned int size) { return _find_first_zero_bit(addr, size); } EXPORT_SYMBOL(find_first_zero_bit); int find_next_zero_bit(void *addr, int size, int offset) { return _find_next_zero_bit(addr, size, offset); } EXPORT_SYMBOL(find_next_zero_bit); |