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1// SPDX-License-Identifier: GPL-2.0-or-later2/* bit search implementation3 *4 * Copied from lib/find_bit.c to tools/lib/find_bit.c5 *6 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.7 * Written by David Howells (dhowells@redhat.com)8 *9 * Copyright (C) 2008 IBM Corporation10 * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>11 * (Inspired by David Howell's find_next_bit implementation)12 *13 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease14 * size and improve performance, 2015.15 */16 17#include <linux/bitops.h>18#include <linux/bitmap.h>19#include <linux/kernel.h>20 21/*22 * Common helper for find_bit() function family23 * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)24 * @MUNGE: The expression that post-processes a word containing found bit (may be empty)25 * @size: The bitmap size in bits26 */27#define FIND_FIRST_BIT(FETCH, MUNGE, size) \28({ \29 unsigned long idx, val, sz = (size); \30 \31 for (idx = 0; idx * BITS_PER_LONG < sz; idx++) { \32 val = (FETCH); \33 if (val) { \34 sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz); \35 break; \36 } \37 } \38 \39 sz; \40})41 42/*43 * Common helper for find_next_bit() function family44 * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)45 * @MUNGE: The expression that post-processes a word containing found bit (may be empty)46 * @size: The bitmap size in bits47 * @start: The bitnumber to start searching at48 */49#define FIND_NEXT_BIT(FETCH, MUNGE, size, start) \50({ \51 unsigned long mask, idx, tmp, sz = (size), __start = (start); \52 \53 if (unlikely(__start >= sz)) \54 goto out; \55 \56 mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start)); \57 idx = __start / BITS_PER_LONG; \58 \59 for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) { \60 if ((idx + 1) * BITS_PER_LONG >= sz) \61 goto out; \62 idx++; \63 } \64 \65 sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz); \66out: \67 sz; \68})69 70#ifndef find_first_bit71/*72 * Find the first set bit in a memory region.73 */74unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)75{76 return FIND_FIRST_BIT(addr[idx], /* nop */, size);77}78#endif79 80#ifndef find_first_and_bit81/*82 * Find the first set bit in two memory regions.83 */84unsigned long _find_first_and_bit(const unsigned long *addr1,85 const unsigned long *addr2,86 unsigned long size)87{88 return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size);89}90#endif91 92#ifndef find_first_zero_bit93/*94 * Find the first cleared bit in a memory region.95 */96unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)97{98 return FIND_FIRST_BIT(~addr[idx], /* nop */, size);99}100#endif101 102#ifndef find_next_bit103unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)104{105 return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);106}107#endif108 109#ifndef find_next_and_bit110unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,111 unsigned long nbits, unsigned long start)112{113 return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);114}115#endif116 117#ifndef find_next_zero_bit118unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,119 unsigned long start)120{121 return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);122}123#endif124