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- // 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 <linux/bitops.h>
- #include <linux/bitmap.h>
- #include <linux/export.h>
- #include <linux/kernel.h>
- #include <linux/minmax.h>
- #if !defined(find_next_bit) || !defined(find_next_zero_bit) || \
- !defined(find_next_bit_le) || !defined(find_next_zero_bit_le) || \
- !defined(find_next_and_bit)
- /*
- * This is a common helper function for find_next_bit, find_next_zero_bit, and
- * find_next_and_bit. The differences are:
- * - The "invert" argument, which is XORed with each fetched word before
- * searching it for one bits.
- * - The optional "addr2", which is anded with "addr1" if present.
- */
- static unsigned long _find_next_bit(const unsigned long *addr1,
- const unsigned long *addr2, unsigned long nbits,
- unsigned long start, unsigned long invert, unsigned long le)
- {
- unsigned long tmp, mask;
- if (unlikely(start >= nbits))
- return nbits;
- tmp = addr1[start / BITS_PER_LONG];
- if (addr2)
- tmp &= addr2[start / BITS_PER_LONG];
- tmp ^= invert;
- /* Handle 1st word. */
- mask = BITMAP_FIRST_WORD_MASK(start);
- if (le)
- mask = swab(mask);
- tmp &= mask;
- start = round_down(start, BITS_PER_LONG);
- while (!tmp) {
- start += BITS_PER_LONG;
- if (start >= nbits)
- return nbits;
- tmp = addr1[start / BITS_PER_LONG];
- if (addr2)
- tmp &= addr2[start / BITS_PER_LONG];
- tmp ^= invert;
- }
- if (le)
- tmp = swab(tmp);
- return min(start + __ffs(tmp), nbits);
- }
- #endif
- #ifndef find_next_bit
- /*
- * Find the next set bit in a memory region.
- */
- unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
- unsigned long offset)
- {
- return _find_next_bit(addr, NULL, size, offset, 0UL, 0);
- }
- EXPORT_SYMBOL(find_next_bit);
- #endif
- #ifndef find_next_zero_bit
- unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
- unsigned long offset)
- {
- return _find_next_bit(addr, NULL, size, offset, ~0UL, 0);
- }
- EXPORT_SYMBOL(find_next_zero_bit);
- #endif
- #if !defined(find_next_and_bit)
- unsigned long find_next_and_bit(const unsigned long *addr1,
- const unsigned long *addr2, unsigned long size,
- unsigned long offset)
- {
- return _find_next_bit(addr1, addr2, size, offset, 0UL, 0);
- }
- EXPORT_SYMBOL(find_next_and_bit);
- #endif
- #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)
- {
- unsigned long idx;
- for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
- if (addr[idx])
- return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
- }
- return 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)
- {
- unsigned long idx;
- for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
- if (addr[idx] != ~0UL)
- return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
- }
- return size;
- }
- EXPORT_SYMBOL(find_first_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
- #ifdef __BIG_ENDIAN
- #ifndef find_next_zero_bit_le
- unsigned long find_next_zero_bit_le(const void *addr, unsigned
- long size, unsigned long offset)
- {
- return _find_next_bit(addr, NULL, size, offset, ~0UL, 1);
- }
- EXPORT_SYMBOL(find_next_zero_bit_le);
- #endif
- #ifndef find_next_bit_le
- unsigned long find_next_bit_le(const void *addr, unsigned
- long size, unsigned long offset)
- {
- return _find_next_bit(addr, NULL, size, offset, 0UL, 1);
- }
- EXPORT_SYMBOL(find_next_bit_le);
- #endif
- #endif /* __BIG_ENDIAN */
- unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
- unsigned long size, unsigned long offset)
- {
- offset = find_next_bit(addr, size, offset);
- if (offset == size)
- return size;
- offset = round_down(offset, 8);
- *clump = bitmap_get_value8(addr, offset);
- return offset;
- }
- EXPORT_SYMBOL(find_next_clump8);
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