| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | #include <linux/compiler.h> |
| 2 | #include <linux/types.h> |
| 3 | #include <asm/intrinsics.h> |
| 4 | #include <linux/module.h> |
| 5 | #include <linux/bitops.h> |
| 6 | |
| 7 | /* |
| 8 | * Find next zero bit in a bitmap reasonably efficiently.. |
| 9 | */ |
| 10 | |
| 11 | int __find_next_zero_bit (const void *addr, unsigned long size, unsigned long offset) |
| 12 | { |
| 13 | unsigned long *p = ((unsigned long *) addr) + (offset >> 6); |
| 14 | unsigned long result = offset & ~63UL; |
| 15 | unsigned long tmp; |
| 16 | |
| 17 | if (offset >= size) |
| 18 | return size; |
| 19 | size -= result; |
| 20 | offset &= 63UL; |
| 21 | if (offset) { |
| 22 | tmp = *(p++); |
| 23 | tmp |= ~0UL >> (64-offset); |
| 24 | if (size < 64) |
| 25 | goto found_first; |
| 26 | if (~tmp) |
| 27 | goto found_middle; |
| 28 | size -= 64; |
| 29 | result += 64; |
| 30 | } |
| 31 | while (size & ~63UL) { |
| 32 | if (~(tmp = *(p++))) |
| 33 | goto found_middle; |
| 34 | result += 64; |
| 35 | size -= 64; |
| 36 | } |
| 37 | if (!size) |
| 38 | return result; |
| 39 | tmp = *p; |
| 40 | found_first: |
| 41 | tmp |= ~0UL << size; |
| 42 | if (tmp == ~0UL) /* any bits zero? */ |
| 43 | return result + size; /* nope */ |
| 44 | found_middle: |
| 45 | return result + ffz(tmp); |
| 46 | } |
| 47 | EXPORT_SYMBOL(__find_next_zero_bit); |
| 48 | |
| 49 | /* |
| 50 | * Find next bit in a bitmap reasonably efficiently.. |
| 51 | */ |
| 52 | int __find_next_bit(const void *addr, unsigned long size, unsigned long offset) |
| 53 | { |
| 54 | unsigned long *p = ((unsigned long *) addr) + (offset >> 6); |
| 55 | unsigned long result = offset & ~63UL; |
| 56 | unsigned long tmp; |
| 57 | |
| 58 | if (offset >= size) |
| 59 | return size; |
| 60 | size -= result; |
| 61 | offset &= 63UL; |
| 62 | if (offset) { |
| 63 | tmp = *(p++); |
| 64 | tmp &= ~0UL << offset; |
| 65 | if (size < 64) |
| 66 | goto found_first; |
| 67 | if (tmp) |
| 68 | goto found_middle; |
| 69 | size -= 64; |
| 70 | result += 64; |
| 71 | } |
| 72 | while (size & ~63UL) { |
| 73 | if ((tmp = *(p++))) |
| 74 | goto found_middle; |
| 75 | result += 64; |
| 76 | size -= 64; |
| 77 | } |
| 78 | if (!size) |
| 79 | return result; |
| 80 | tmp = *p; |
| 81 | found_first: |
| 82 | tmp &= ~0UL >> (64-size); |
| 83 | if (tmp == 0UL) /* Are any bits set? */ |
| 84 | return result + size; /* Nope. */ |
| 85 | found_middle: |
| 86 | return result + __ffs(tmp); |
| 87 | } |
| 88 | EXPORT_SYMBOL(__find_next_bit); |