diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/bitops.h | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 40d54731de7..48bde600a2d 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -112,4 +112,144 @@ static inline unsigned fls_long(unsigned long l) return fls64(l); } +#ifdef __KERNEL__ +#ifdef CONFIG_GENERIC_FIND_FIRST_BIT +extern unsigned long __find_first_bit(const unsigned long *addr, + unsigned long size); + +/** + * find_first_bit - find the first set bit in a memory region + * @addr: The address to start the search at + * @size: The maximum size to search + * + * Returns the bit number of the first set bit. + */ +static __always_inline unsigned long +find_first_bit(const unsigned long *addr, unsigned long size) +{ + /* Avoid a function call if the bitmap size is a constant */ + /* and not bigger than BITS_PER_LONG. */ + + /* insert a sentinel so that __ffs returns size if there */ + /* are no set bits in the bitmap */ + if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) + return __ffs((*addr) | (1ul << size)); + + /* the result of __ffs(0) is undefined, so it needs to be */ + /* handled separately */ + if (__builtin_constant_p(size) && (size == BITS_PER_LONG)) + return ((*addr) == 0) ? BITS_PER_LONG : __ffs(*addr); + + /* size is not constant or too big */ + return __find_first_bit(addr, size); +} + +extern unsigned long __find_first_zero_bit(const unsigned long *addr, + unsigned long size); + +/** + * find_first_zero_bit - find the first cleared bit in a memory region + * @addr: The address to start the search at + * @size: The maximum size to search + * + * Returns the bit number of the first cleared bit. + */ +static __always_inline unsigned long +find_first_zero_bit(const unsigned long *addr, unsigned long size) +{ + /* Avoid a function call if the bitmap size is a constant */ + /* and not bigger than BITS_PER_LONG. */ + + /* insert a sentinel so that __ffs returns size if there */ + /* are no set bits in the bitmap */ + if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) { + return __ffs(~(*addr) | (1ul << size)); + } + + /* the result of __ffs(0) is undefined, so it needs to be */ + /* handled separately */ + if (__builtin_constant_p(size) && (size == BITS_PER_LONG)) + return (~(*addr) == 0) ? BITS_PER_LONG : __ffs(~(*addr)); + + /* size is not constant or too big */ + return __find_first_zero_bit(addr, size); +} +#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */ + +#ifdef CONFIG_GENERIC_FIND_NEXT_BIT +extern unsigned long __find_next_bit(const unsigned long *addr, + unsigned long size, unsigned long offset); + +/** + * 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 bitmap size in bits + */ +static __always_inline unsigned long +find_next_bit(const unsigned long *addr, unsigned long size, + unsigned long offset) +{ + unsigned long value; + + /* Avoid a function call if the bitmap size is a constant */ + /* and not bigger than BITS_PER_LONG. */ + + /* insert a sentinel so that __ffs returns size if there */ + /* are no set bits in the bitmap */ + if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) { + value = (*addr) & ((~0ul) << offset); + value |= (1ul << size); + return __ffs(value); + } + + /* the result of __ffs(0) is undefined, so it needs to be */ + /* handled separately */ + if (__builtin_constant_p(size) && (size == BITS_PER_LONG)) { + value = (*addr) & ((~0ul) << offset); + return (value == 0) ? BITS_PER_LONG : __ffs(value); + } + + /* size is not constant or too big */ + return __find_next_bit(addr, size, offset); +} + +extern unsigned long __find_next_zero_bit(const unsigned long *addr, + unsigned long size, unsigned long offset); + +/** + * find_next_zero_bit - find the next cleared bit in a memory region + * @addr: The address to base the search on + * @offset: The bitnumber to start searching at + * @size: The bitmap size in bits + */ +static __always_inline unsigned long +find_next_zero_bit(const unsigned long *addr, unsigned long size, + unsigned long offset) +{ + unsigned long value; + + /* Avoid a function call if the bitmap size is a constant */ + /* and not bigger than BITS_PER_LONG. */ + + /* insert a sentinel so that __ffs returns size if there */ + /* are no set bits in the bitmap */ + if (__builtin_constant_p(size) && (size < BITS_PER_LONG)) { + value = (~(*addr)) & ((~0ul) << offset); + value |= (1ul << size); + return __ffs(value); + } + + /* the result of __ffs(0) is undefined, so it needs to be */ + /* handled separately */ + if (__builtin_constant_p(size) && (size == BITS_PER_LONG)) { + value = (~(*addr)) & ((~0ul) << offset); + return (value == 0) ? BITS_PER_LONG : __ffs(value); + } + + /* size is not constant or too big */ + return __find_next_zero_bit(addr, size, offset); +} +#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */ +#endif /* __KERNEL__ */ #endif |