| Arnaldo Carvalho de Melo | 23e1a35 | 2014-12-15 19:50:12 -0300 | [diff] [blame^] | 1 | /* find_next_bit.c: fallback find next bit implementation |
| 2 | * |
| 3 | * Copied from lib/find_next_bit.c to tools/lib/next_bit.c |
| 4 | * |
| 5 | * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. |
| 6 | * Written by David Howells (dhowells@redhat.com) |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU General Public License |
| 10 | * as published by the Free Software Foundation; either version |
| 11 | * 2 of the License, or (at your option) any later version. |
| 12 | */ |
| 13 | |
| 14 | #include <linux/bitops.h> |
| 15 | #include <asm/types.h> |
| 16 | #include <asm/byteorder.h> |
| 17 | |
| 18 | #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) |
| 19 | |
| 20 | #ifndef find_next_bit |
| 21 | /* |
| 22 | * Find the next set bit in a memory region. |
| 23 | */ |
| 24 | unsigned long find_next_bit(const unsigned long *addr, unsigned long size, |
| 25 | unsigned long offset) |
| 26 | { |
| 27 | const unsigned long *p = addr + BITOP_WORD(offset); |
| 28 | unsigned long result = offset & ~(BITS_PER_LONG-1); |
| 29 | unsigned long tmp; |
| 30 | |
| 31 | if (offset >= size) |
| 32 | return size; |
| 33 | size -= result; |
| 34 | offset %= BITS_PER_LONG; |
| 35 | if (offset) { |
| 36 | tmp = *(p++); |
| 37 | tmp &= (~0UL << offset); |
| 38 | if (size < BITS_PER_LONG) |
| 39 | goto found_first; |
| 40 | if (tmp) |
| 41 | goto found_middle; |
| 42 | size -= BITS_PER_LONG; |
| 43 | result += BITS_PER_LONG; |
| 44 | } |
| 45 | while (size & ~(BITS_PER_LONG-1)) { |
| 46 | if ((tmp = *(p++))) |
| 47 | goto found_middle; |
| 48 | result += BITS_PER_LONG; |
| 49 | size -= BITS_PER_LONG; |
| 50 | } |
| 51 | if (!size) |
| 52 | return result; |
| 53 | tmp = *p; |
| 54 | |
| 55 | found_first: |
| 56 | tmp &= (~0UL >> (BITS_PER_LONG - size)); |
| 57 | if (tmp == 0UL) /* Are any bits set? */ |
| 58 | return result + size; /* Nope. */ |
| 59 | found_middle: |
| 60 | return result + __ffs(tmp); |
| 61 | } |
| 62 | #endif |
| 63 | |
| 64 | #ifndef find_first_bit |
| 65 | /* |
| 66 | * Find the first set bit in a memory region. |
| 67 | */ |
| 68 | unsigned long find_first_bit(const unsigned long *addr, unsigned long size) |
| 69 | { |
| 70 | const unsigned long *p = addr; |
| 71 | unsigned long result = 0; |
| 72 | unsigned long tmp; |
| 73 | |
| 74 | while (size & ~(BITS_PER_LONG-1)) { |
| 75 | if ((tmp = *(p++))) |
| 76 | goto found; |
| 77 | result += BITS_PER_LONG; |
| 78 | size -= BITS_PER_LONG; |
| 79 | } |
| 80 | if (!size) |
| 81 | return result; |
| 82 | |
| 83 | tmp = (*p) & (~0UL >> (BITS_PER_LONG - size)); |
| 84 | if (tmp == 0UL) /* Are any bits set? */ |
| 85 | return result + size; /* Nope. */ |
| 86 | found: |
| 87 | return result + __ffs(tmp); |
| 88 | } |
| 89 | #endif |