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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124// 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_bitunsigned 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_bitunsigned 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_bitunsigned 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