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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 | // SPDX-License-Identifier: GPL-2.0-or-later /* bit search implementation * * Copied from lib/find_bit.c to tools/lib/find_bit.c * * 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 <linux/bitops.h> #include <linux/bitmap.h> #include <linux/kernel.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); } #endif #ifndef find_first_and_bit /* * Find the first set bit in two memory regions. */ unsigned long _find_first_and_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long size) { return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size); } #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); } #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); } #endif #ifndef find_next_and_bit unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2, unsigned long nbits, unsigned long start) { return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start); } #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); } #endif |