1 /* 2 * MSB0 numbered special bitops handling. 3 * 4 * On s390x the bits are numbered: 5 * |0..............63|64............127|128...........191|192...........255| 6 * and on s390: 7 * |0.....31|32....63|64....95|96...127|128..159|160..191|192..223|224..255| 8 * 9 * The reason for this bit numbering is the fact that the hardware sets bits 10 * in a bitmap starting at bit 0 (MSB) and we don't want to scan the bitmap 11 * from the 'wrong end'. 12 */ 13 14 #include <linux/compiler.h> 15 #include <linux/bitops.h> 16 #include <linux/export.h> 17 18 unsigned long find_first_bit_inv(const unsigned long *addr, unsigned long size) 19 { 20 const unsigned long *p = addr; 21 unsigned long result = 0; 22 unsigned long tmp; 23 24 while (size & ~(BITS_PER_LONG - 1)) { 25 if ((tmp = *(p++))) 26 goto found; 27 result += BITS_PER_LONG; 28 size -= BITS_PER_LONG; 29 } 30 if (!size) 31 return result; 32 tmp = (*p) & (~0UL << (BITS_PER_LONG - size)); 33 if (!tmp) /* Are any bits set? */ 34 return result + size; /* Nope. */ 35 found: 36 return result + (__fls(tmp) ^ (BITS_PER_LONG - 1)); 37 } 38 EXPORT_SYMBOL(find_first_bit_inv); 39 40 unsigned long find_next_bit_inv(const unsigned long *addr, unsigned long size, 41 unsigned long offset) 42 { 43 const unsigned long *p = addr + (offset / BITS_PER_LONG); 44 unsigned long result = offset & ~(BITS_PER_LONG - 1); 45 unsigned long tmp; 46 47 if (offset >= size) 48 return size; 49 size -= result; 50 offset %= BITS_PER_LONG; 51 if (offset) { 52 tmp = *(p++); 53 tmp &= (~0UL >> offset); 54 if (size < BITS_PER_LONG) 55 goto found_first; 56 if (tmp) 57 goto found_middle; 58 size -= BITS_PER_LONG; 59 result += BITS_PER_LONG; 60 } 61 while (size & ~(BITS_PER_LONG-1)) { 62 if ((tmp = *(p++))) 63 goto found_middle; 64 result += BITS_PER_LONG; 65 size -= BITS_PER_LONG; 66 } 67 if (!size) 68 return result; 69 tmp = *p; 70 found_first: 71 tmp &= (~0UL << (BITS_PER_LONG - size)); 72 if (!tmp) /* Are any bits set? */ 73 return result + size; /* Nope. */ 74 found_middle: 75 return result + (__fls(tmp) ^ (BITS_PER_LONG - 1)); 76 } 77 EXPORT_SYMBOL(find_next_bit_inv); 78