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252 lines
6.6 KiB
252 lines
6.6 KiB
// 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 ([email protected]) |
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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 <[email protected]> |
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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 <[email protected]> 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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/* |
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* Common helper for find_bit() function family |
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* @FETCH: The expression that fetches and pre-processes each word of bitmap(s) |
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* @MUNGE: The expression that post-processes a word containing found bit (may be empty) |
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* @size: The bitmap size in bits |
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*/ |
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#define FIND_FIRST_BIT(FETCH, MUNGE, size) \ |
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({ \ |
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unsigned long idx, val, sz = (size); \ |
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\ |
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for (idx = 0; idx * BITS_PER_LONG < sz; idx++) { \ |
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val = (FETCH); \ |
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if (val) { \ |
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sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz); \ |
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break; \ |
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} \ |
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} \ |
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\ |
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sz; \ |
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}) |
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/* |
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* Common helper for find_next_bit() function family |
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* @FETCH: The expression that fetches and pre-processes each word of bitmap(s) |
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* @MUNGE: The expression that post-processes a word containing found bit (may be empty) |
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* @size: The bitmap size in bits |
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* @start: The bitnumber to start searching at |
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*/ |
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#define FIND_NEXT_BIT(FETCH, MUNGE, size, start) \ |
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({ \ |
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unsigned long mask, idx, tmp, sz = (size), __start = (start); \ |
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\ |
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if (unlikely(__start >= sz)) \ |
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goto out; \ |
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\ |
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mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start)); \ |
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idx = __start / BITS_PER_LONG; \ |
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\ |
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for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) { \ |
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if ((idx + 1) * BITS_PER_LONG >= sz) \ |
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goto out; \ |
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idx++; \ |
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} \ |
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\ |
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sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz); \ |
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out: \ |
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sz; \ |
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}) |
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#define FIND_NTH_BIT(FETCH, size, num) \ |
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({ \ |
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unsigned long sz = (size), nr = (num), idx, w, tmp; \ |
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\ |
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for (idx = 0; (idx + 1) * BITS_PER_LONG <= sz; idx++) { \ |
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if (idx * BITS_PER_LONG + nr >= sz) \ |
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goto out; \ |
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\ |
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tmp = (FETCH); \ |
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w = hweight_long(tmp); \ |
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if (w > nr) \ |
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goto found; \ |
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\ |
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nr -= w; \ |
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} \ |
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\ |
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if (sz % BITS_PER_LONG) \ |
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tmp = (FETCH) & BITMAP_LAST_WORD_MASK(sz); \ |
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found: \ |
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sz = min(idx * BITS_PER_LONG + fns(tmp, nr), sz); \ |
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out: \ |
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sz; \ |
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}) |
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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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return FIND_FIRST_BIT(addr[idx], /* nop */, 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_and_bit |
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/* |
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* Find the first set bit in two memory regions. |
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*/ |
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unsigned long _find_first_and_bit(const unsigned long *addr1, |
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const unsigned long *addr2, |
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unsigned long size) |
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{ |
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return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size); |
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} |
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EXPORT_SYMBOL(_find_first_and_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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return FIND_FIRST_BIT(~addr[idx], /* nop */, 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_next_bit |
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unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start) |
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{ |
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return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start); |
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} |
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EXPORT_SYMBOL(_find_next_bit); |
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#endif |
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unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n) |
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{ |
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return FIND_NTH_BIT(addr[idx], size, n); |
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} |
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EXPORT_SYMBOL(__find_nth_bit); |
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unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2, |
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unsigned long size, unsigned long n) |
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{ |
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return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n); |
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} |
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EXPORT_SYMBOL(__find_nth_and_bit); |
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unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, |
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unsigned long size, unsigned long n) |
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{ |
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return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n); |
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} |
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EXPORT_SYMBOL(__find_nth_andnot_bit); |
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#ifndef find_next_and_bit |
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unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2, |
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unsigned long nbits, unsigned long start) |
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{ |
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return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start); |
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} |
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EXPORT_SYMBOL(_find_next_and_bit); |
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#endif |
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#ifndef find_next_andnot_bit |
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unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, |
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unsigned long nbits, unsigned long start) |
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{ |
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return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start); |
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} |
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EXPORT_SYMBOL(_find_next_andnot_bit); |
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#endif |
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#ifndef find_next_zero_bit |
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unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits, |
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unsigned long start) |
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{ |
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return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start); |
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} |
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EXPORT_SYMBOL(_find_next_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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#ifdef __BIG_ENDIAN |
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#ifndef find_first_zero_bit_le |
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/* |
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* Find the first cleared bit in an LE memory region. |
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*/ |
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unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size) |
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{ |
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return FIND_FIRST_BIT(~addr[idx], swab, size); |
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} |
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EXPORT_SYMBOL(_find_first_zero_bit_le); |
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#endif |
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#ifndef find_next_zero_bit_le |
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unsigned long _find_next_zero_bit_le(const unsigned long *addr, |
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unsigned long size, unsigned long offset) |
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{ |
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return FIND_NEXT_BIT(~addr[idx], swab, size, offset); |
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} |
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EXPORT_SYMBOL(_find_next_zero_bit_le); |
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#endif |
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#ifndef find_next_bit_le |
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unsigned long _find_next_bit_le(const unsigned long *addr, |
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unsigned long size, unsigned long offset) |
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{ |
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return FIND_NEXT_BIT(addr[idx], swab, size, offset); |
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} |
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EXPORT_SYMBOL(_find_next_bit_le); |
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#endif |
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#endif /* __BIG_ENDIAN */
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