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