| 1 | // SPDX-License-Identifier: GPL-2.0 |
|---|---|
| 2 | /* |
| 3 | * MSB0 numbered special bitops handling. |
| 4 | * |
| 5 | * The bits are numbered: |
| 6 | * |0..............63|64............127|128...........191|192...........255| |
| 7 | * |
| 8 | * The reason for this bit numbering is the fact that the hardware sets bits |
| 9 | * in a bitmap starting at bit 0 (MSB) and we don't want to scan the bitmap |
| 10 | * from the 'wrong end'. |
| 11 | */ |
| 12 | |
| 13 | #include <linux/compiler.h> |
| 14 | #include <linux/bitops.h> |
| 15 | #include <linux/export.h> |
| 16 | |
| 17 | unsigned long find_first_bit_inv(const unsigned long *addr, unsigned long size) |
| 18 | { |
| 19 | const unsigned long *p = addr; |
| 20 | unsigned long result = 0; |
| 21 | unsigned long tmp; |
| 22 | |
| 23 | while (size & ~(BITS_PER_LONG - 1)) { |
| 24 | if ((tmp = *(p++))) |
| 25 | goto found; |
| 26 | result += BITS_PER_LONG; |
| 27 | size -= BITS_PER_LONG; |
| 28 | } |
| 29 | if (!size) |
| 30 | return result; |
| 31 | tmp = (*p) & (~0UL << (BITS_PER_LONG - size)); |
| 32 | if (!tmp) /* Are any bits set? */ |
| 33 | return result + size; /* Nope. */ |
| 34 | found: |
| 35 | return result + (__fls(word: tmp) ^ (BITS_PER_LONG - 1)); |
| 36 | } |
| 37 | EXPORT_SYMBOL(find_first_bit_inv); |
| 38 | |
| 39 | unsigned long find_next_bit_inv(const unsigned long *addr, unsigned long size, |
| 40 | unsigned long offset) |
| 41 | { |
| 42 | const unsigned long *p = addr + (offset / BITS_PER_LONG); |
| 43 | unsigned long result = offset & ~(BITS_PER_LONG - 1); |
| 44 | unsigned long tmp; |
| 45 | |
| 46 | if (offset >= size) |
| 47 | return size; |
| 48 | size -= result; |
| 49 | offset %= BITS_PER_LONG; |
| 50 | if (offset) { |
| 51 | tmp = *(p++); |
| 52 | tmp &= (~0UL >> offset); |
| 53 | if (size < BITS_PER_LONG) |
| 54 | goto found_first; |
| 55 | if (tmp) |
| 56 | goto found_middle; |
| 57 | size -= BITS_PER_LONG; |
| 58 | result += BITS_PER_LONG; |
| 59 | } |
| 60 | while (size & ~(BITS_PER_LONG-1)) { |
| 61 | if ((tmp = *(p++))) |
| 62 | goto found_middle; |
| 63 | result += BITS_PER_LONG; |
| 64 | size -= BITS_PER_LONG; |
| 65 | } |
| 66 | if (!size) |
| 67 | return result; |
| 68 | tmp = *p; |
| 69 | found_first: |
| 70 | tmp &= (~0UL << (BITS_PER_LONG - size)); |
| 71 | if (!tmp) /* Are any bits set? */ |
| 72 | return result + size; /* Nope. */ |
| 73 | found_middle: |
| 74 | return result + (__fls(word: tmp) ^ (BITS_PER_LONG - 1)); |
| 75 | } |
| 76 | EXPORT_SYMBOL(find_next_bit_inv); |
| 77 |