diff options
Diffstat (limited to 'lib/find_next_bit.c')
| -rw-r--r-- | lib/find_next_bit.c | 69 |
1 files changed, 60 insertions, 9 deletions
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c index 78ccd73a884..24c59ded47a 100644 --- a/lib/find_next_bit.c +++ b/lib/find_next_bit.c @@ -16,14 +16,12 @@ #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) -/** - * find_next_bit - find the next set bit in a memory region - * @addr: The address to base the search on - * @offset: The bitnumber to start searching at - * @size: The maximum size to search +#ifdef CONFIG_GENERIC_FIND_NEXT_BIT +/* + * Find the next set bit in a memory region. */ unsigned long find_next_bit(const unsigned long *addr, unsigned long size, - unsigned long offset) + unsigned long offset) { const unsigned long *p = addr + BITOP_WORD(offset); unsigned long result = offset & ~(BITS_PER_LONG-1); @@ -60,7 +58,6 @@ found_first: found_middle: return result + __ffs(tmp); } - EXPORT_SYMBOL(find_next_bit); /* @@ -68,7 +65,7 @@ EXPORT_SYMBOL(find_next_bit); * Linus' asm-alpha/bitops.h. */ unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, - unsigned long offset) + unsigned long offset) { const unsigned long *p = addr + BITOP_WORD(offset); unsigned long result = offset & ~(BITS_PER_LONG-1); @@ -105,8 +102,62 @@ found_first: found_middle: return result + ffz(tmp); } - EXPORT_SYMBOL(find_next_zero_bit); +#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */ + +#ifdef CONFIG_GENERIC_FIND_FIRST_BIT +/* + * Find the first set bit in a memory region. + */ +unsigned long find_first_bit(const unsigned long *addr, unsigned long size) +{ + const unsigned long *p = addr; + unsigned long result = 0; + unsigned long tmp; + + while (size & ~(BITS_PER_LONG-1)) { + if ((tmp = *(p++))) + goto found; + result += BITS_PER_LONG; + size -= BITS_PER_LONG; + } + if (!size) + return result; + + tmp = (*p) & (~0UL >> (BITS_PER_LONG - size)); + if (tmp == 0UL) /* Are any bits set? */ + return result + size; /* Nope. */ +found: + return result + __ffs(tmp); +} +EXPORT_SYMBOL(find_first_bit); + +/* + * Find the first cleared bit in a memory region. + */ +unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size) +{ + const unsigned long *p = addr; + unsigned long result = 0; + unsigned long tmp; + + while (size & ~(BITS_PER_LONG-1)) { + if (~(tmp = *(p++))) + goto found; + result += BITS_PER_LONG; + size -= BITS_PER_LONG; + } + if (!size) + return result; + + tmp = (*p) | (~0UL << size); + if (tmp == ~0UL) /* Are any bits zero? */ + return result + size; /* Nope. */ +found: + return result + ffz(tmp); +} +EXPORT_SYMBOL(find_first_zero_bit); +#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */ #ifdef __BIG_ENDIAN |