| /* find_next_bit.c: fallback find next bit implementation |
| * |
| * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #include <common.h> |
| #include <errno.h> |
| #include <string.h> |
| #include <init.h> |
| #include <linux/bitops.h> |
| #include <asm/types.h> |
| #include <asm/byteorder.h> |
| |
| #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) |
| |
| #ifdef CONFIG_GENERIC_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) |
| { |
| const unsigned long *p = addr + BITOP_WORD(offset); |
| unsigned long result = offset & ~(BITS_PER_LONG-1); |
| unsigned long tmp; |
| |
| if (offset >= size) |
| return size; |
| size -= result; |
| offset %= BITS_PER_LONG; |
| if (offset) { |
| tmp = *(p++); |
| tmp &= (~0UL << offset); |
| if (size < BITS_PER_LONG) |
| goto found_first; |
| if (tmp) |
| goto found_middle; |
| size -= BITS_PER_LONG; |
| result += BITS_PER_LONG; |
| } |
| while (size & ~(BITS_PER_LONG-1)) { |
| if ((tmp = *(p++))) |
| goto found_middle; |
| result += BITS_PER_LONG; |
| size -= BITS_PER_LONG; |
| } |
| if (!size) |
| return result; |
| tmp = *p; |
| |
| found_first: |
| tmp &= (~0UL >> (BITS_PER_LONG - size)); |
| if (tmp == 0UL) /* Are any bits set? */ |
| return result + size; /* Nope. */ |
| found_middle: |
| return result + __ffs(tmp); |
| } |
| EXPORT_SYMBOL(find_next_bit); |
| |
| /* |
| * This implementation of find_{first,next}_zero_bit was stolen from |
| * Linus' asm-alpha/bitops.h. |
| */ |
| unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, |
| unsigned long offset) |
| { |
| const unsigned long *p = addr + BITOP_WORD(offset); |
| unsigned long result = offset & ~(BITS_PER_LONG-1); |
| unsigned long tmp; |
| |
| if (offset >= size) |
| return size; |
| size -= result; |
| offset %= BITS_PER_LONG; |
| if (offset) { |
| tmp = *(p++); |
| tmp |= ~0UL >> (BITS_PER_LONG - offset); |
| if (size < BITS_PER_LONG) |
| goto found_first; |
| if (~tmp) |
| goto found_middle; |
| size -= BITS_PER_LONG; |
| result += BITS_PER_LONG; |
| } |
| while (size & ~(BITS_PER_LONG-1)) { |
| if (~(tmp = *(p++))) |
| goto found_middle; |
| result += BITS_PER_LONG; |
| size -= BITS_PER_LONG; |
| } |
| if (!size) |
| return result; |
| tmp = *p; |
| |
| found_first: |
| tmp |= ~0UL << size; |
| if (tmp == ~0UL) /* Are any bits zero? */ |
| return result + size; /* Nope. */ |
| found_middle: |
| return result + ffz(tmp); |
| } |
| EXPORT_SYMBOL(find_next_zero_bit); |
| #endif /* CONFIG_GENERIC_FIND_NEXT_BIT */ |