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![Yury Norov](/assets/img/avatar_default.png)
Similarly to bitmap functions, users would benefit if we'll handle a case of small-size bitmaps that fit into a single word. While here, move the find_last_bit() declaration to bitops/find.h where other find_*_bit() functions sit. Link: https://lkml.kernel.org/r/20210401003153.97325-11-yury.norov@gmail.com Signed-off-by: Yury Norov <yury.norov@gmail.com> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Alexey Klimov <aklimov@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: David Sterba <dsterba@suse.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Jianpeng Ma <jianpeng.ma@intel.com> Cc: Joe Perches <joe@perches.com> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Rich Felker <dalias@libc.org> Cc: Stefano Brivio <sbrivio@redhat.com> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: Wolfram Sang <wsa+renesas@sang-engineering.com> Cc: Yoshinori Sato <ysato@users.osdn.me> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
142 lines
3.3 KiB
C
142 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* bit search implementation
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* Copyright (C) 2008 IBM Corporation
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* 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
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* (Inspired by David Howell's find_next_bit implementation)
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*
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* Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
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* size and improve performance, 2015.
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*/
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#include <linux/bitops.h>
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#include <linux/bitmap.h>
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#include <linux/export.h>
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#include <linux/math.h>
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#include <linux/minmax.h>
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#include <linux/swab.h>
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#if !defined(find_next_bit) || !defined(find_next_zero_bit) || \
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!defined(find_next_bit_le) || !defined(find_next_zero_bit_le) || \
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!defined(find_next_and_bit)
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/*
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* This is a common helper function for find_next_bit, find_next_zero_bit, and
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* find_next_and_bit. The differences are:
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* - The "invert" argument, which is XORed with each fetched word before
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* searching it for one bits.
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* - The optional "addr2", which is anded with "addr1" if present.
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*/
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unsigned long _find_next_bit(const unsigned long *addr1,
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const unsigned long *addr2, unsigned long nbits,
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unsigned long start, unsigned long invert, unsigned long le)
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{
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unsigned long tmp, mask;
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if (unlikely(start >= nbits))
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return nbits;
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tmp = addr1[start / BITS_PER_LONG];
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if (addr2)
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tmp &= addr2[start / BITS_PER_LONG];
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tmp ^= invert;
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/* Handle 1st word. */
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mask = BITMAP_FIRST_WORD_MASK(start);
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if (le)
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mask = swab(mask);
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tmp &= mask;
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start = round_down(start, BITS_PER_LONG);
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while (!tmp) {
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start += BITS_PER_LONG;
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if (start >= nbits)
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return nbits;
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tmp = addr1[start / BITS_PER_LONG];
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if (addr2)
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tmp &= addr2[start / BITS_PER_LONG];
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tmp ^= invert;
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}
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if (le)
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tmp = swab(tmp);
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return min(start + __ffs(tmp), nbits);
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}
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EXPORT_SYMBOL(_find_next_bit);
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#endif
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#ifndef find_first_bit
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/*
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* Find the first set bit in a memory region.
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*/
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unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
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{
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unsigned long idx;
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for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
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if (addr[idx])
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return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
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}
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return size;
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}
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EXPORT_SYMBOL(_find_first_bit);
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#endif
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#ifndef find_first_zero_bit
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/*
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* Find the first cleared bit in a memory region.
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*/
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unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
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{
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unsigned long idx;
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for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
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if (addr[idx] != ~0UL)
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return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
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}
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return size;
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}
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EXPORT_SYMBOL(_find_first_zero_bit);
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#endif
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#ifndef find_last_bit
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unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
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{
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if (size) {
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unsigned long val = BITMAP_LAST_WORD_MASK(size);
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unsigned long idx = (size-1) / BITS_PER_LONG;
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do {
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val &= addr[idx];
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if (val)
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return idx * BITS_PER_LONG + __fls(val);
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val = ~0ul;
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} while (idx--);
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}
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return size;
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}
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EXPORT_SYMBOL(_find_last_bit);
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#endif
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unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
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unsigned long size, unsigned long offset)
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{
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offset = find_next_bit(addr, size, offset);
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if (offset == size)
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return size;
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offset = round_down(offset, 8);
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*clump = bitmap_get_value8(addr, offset);
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return offset;
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}
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EXPORT_SYMBOL(find_next_clump8);
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