| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | #include <linux/bitops.h> |
| 2 | |
| 3 | /** |
| 4 | * find_next_bit - find the next set bit in a memory region |
| 5 | * @addr: The address to base the search on |
| 6 | * @offset: The bitnumber to start searching at |
| 7 | * @size: The maximum size to search |
| 8 | */ |
| 9 | unsigned long find_next_bit(const unsigned long *addr, unsigned long size, |
| 10 | unsigned long offset) |
| 11 | { |
| 12 | const unsigned long *p = addr + (offset >> 6); |
| 13 | unsigned long result = offset & ~63UL; |
| 14 | unsigned long tmp; |
| 15 | |
| 16 | if (offset >= size) |
| 17 | return size; |
| 18 | size -= result; |
| 19 | offset &= 63UL; |
| 20 | if (offset) { |
| 21 | tmp = *(p++); |
| 22 | tmp &= (~0UL << offset); |
| 23 | if (size < 64) |
| 24 | goto found_first; |
| 25 | if (tmp) |
| 26 | goto found_middle; |
| 27 | size -= 64; |
| 28 | result += 64; |
| 29 | } |
| 30 | while (size & ~63UL) { |
| 31 | if ((tmp = *(p++))) |
| 32 | goto found_middle; |
| 33 | result += 64; |
| 34 | size -= 64; |
| 35 | } |
| 36 | if (!size) |
| 37 | return result; |
| 38 | tmp = *p; |
| 39 | |
| 40 | found_first: |
| 41 | tmp &= (~0UL >> (64 - size)); |
| 42 | if (tmp == 0UL) /* Are any bits set? */ |
| 43 | return result + size; /* Nope. */ |
| 44 | found_middle: |
| 45 | return result + __ffs(tmp); |
| 46 | } |
| 47 | |
| 48 | /* find_next_zero_bit() finds the first zero bit in a bit string of length |
| 49 | * 'size' bits, starting the search at bit 'offset'. This is largely based |
| 50 | * on Linus's ALPHA routines, which are pretty portable BTW. |
| 51 | */ |
| 52 | |
| 53 | unsigned long find_next_zero_bit(const unsigned long *addr, |
| 54 | unsigned long size, unsigned long offset) |
| 55 | { |
| 56 | const unsigned long *p = addr + (offset >> 6); |
| 57 | unsigned long result = offset & ~63UL; |
| 58 | unsigned long tmp; |
| 59 | |
| 60 | if (offset >= size) |
| 61 | return size; |
| 62 | size -= result; |
| 63 | offset &= 63UL; |
| 64 | if (offset) { |
| 65 | tmp = *(p++); |
| 66 | tmp |= ~0UL >> (64-offset); |
| 67 | if (size < 64) |
| 68 | goto found_first; |
| 69 | if (~tmp) |
| 70 | goto found_middle; |
| 71 | size -= 64; |
| 72 | result += 64; |
| 73 | } |
| 74 | while (size & ~63UL) { |
| 75 | if (~(tmp = *(p++))) |
| 76 | goto found_middle; |
| 77 | result += 64; |
| 78 | size -= 64; |
| 79 | } |
| 80 | if (!size) |
| 81 | return result; |
| 82 | tmp = *p; |
| 83 | |
| 84 | found_first: |
| 85 | tmp |= ~0UL << size; |
| 86 | if (tmp == ~0UL) /* Are any bits zero? */ |
| 87 | return result + size; /* Nope. */ |
| 88 | found_middle: |
| 89 | return result + ffz(tmp); |
| 90 | } |
| 91 | |
| 92 | unsigned long find_next_zero_le_bit(unsigned long *addr, unsigned long size, unsigned long offset) |
| 93 | { |
| 94 | unsigned long *p = addr + (offset >> 6); |
| 95 | unsigned long result = offset & ~63UL; |
| 96 | unsigned long tmp; |
| 97 | |
| 98 | if (offset >= size) |
| 99 | return size; |
| 100 | size -= result; |
| 101 | offset &= 63UL; |
| 102 | if(offset) { |
| 103 | tmp = __swab64p(p++); |
| 104 | tmp |= (~0UL >> (64-offset)); |
| 105 | if(size < 64) |
| 106 | goto found_first; |
| 107 | if(~tmp) |
| 108 | goto found_middle; |
| 109 | size -= 64; |
| 110 | result += 64; |
| 111 | } |
| 112 | while(size & ~63) { |
| 113 | if(~(tmp = __swab64p(p++))) |
| 114 | goto found_middle; |
| 115 | result += 64; |
| 116 | size -= 64; |
| 117 | } |
| 118 | if(!size) |
| 119 | return result; |
| 120 | tmp = __swab64p(p); |
| 121 | found_first: |
| 122 | tmp |= (~0UL << size); |
| 123 | if (tmp == ~0UL) /* Are any bits zero? */ |
| 124 | return result + size; /* Nope. */ |
| 125 | found_middle: |
| 126 | return result + ffz(tmp); |
| 127 | } |