56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
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/* find_next_bit.c: fallback find next bit 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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* 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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int find_next_bit(const unsigned long *addr, int size, int offset)
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{
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const unsigned long *base;
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const int NBITS = sizeof(*addr) * 8;
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unsigned long tmp;
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base = addr;
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if (offset) {
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int suboffset;
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addr += offset / NBITS;
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suboffset = offset % NBITS;
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if (suboffset) {
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tmp = *addr;
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tmp >>= suboffset;
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if (tmp)
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goto finish;
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}
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addr++;
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}
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while ((tmp = *addr) == 0)
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addr++;
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offset = (addr - base) * NBITS;
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finish:
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/* count the remaining bits without using __ffs() since that takes a 32-bit arg */
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while (!(tmp & 0xff)) {
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offset += 8;
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tmp >>= 8;
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}
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while (!(tmp & 1)) {
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offset++;
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tmp >>= 1;
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}
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return offset;
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}
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