46 lines
1.1 KiB
C
46 lines
1.1 KiB
C
/* find_last_bit.c: fallback find next bit implementation
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*
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* Copyright (C) 2008 IBM Corporation
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* 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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/bitops.h>
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#include <linux/module.h>
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#include <asm/types.h>
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#include <asm/byteorder.h>
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unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
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{
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unsigned long words;
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unsigned long tmp;
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/* Start at final word. */
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words = size / BITS_PER_LONG;
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/* Partial final word? */
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if (size & (BITS_PER_LONG-1)) {
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tmp = (addr[words] & (~0UL >> (BITS_PER_LONG
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- (size & (BITS_PER_LONG-1)))));
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if (tmp)
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goto found;
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}
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while (words) {
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tmp = addr[--words];
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if (tmp) {
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found:
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return words * BITS_PER_LONG + __fls(tmp);
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}
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}
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/* Not found */
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return size;
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}
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EXPORT_SYMBOL(find_last_bit);
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