diff options
Diffstat (limited to 'include/linux/bitops.h')
| -rw-r--r-- | include/linux/bitops.h | 85 |
1 files changed, 49 insertions, 36 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 2ba557e067fe..9be2d50da09a 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -8,19 +8,13 @@ #include <uapi/linux/kernel.h> -/* Set bits in the first 'n' bytes when loaded from memory */ -#ifdef __LITTLE_ENDIAN -# define aligned_byte_mask(n) ((1UL << 8*(n))-1) -#else -# define aligned_byte_mask(n) (~0xffUL << (BITS_PER_LONG - 8 - 8*(n))) -#endif - -#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE) #define BITS_TO_LONGS(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long)) #define BITS_TO_U64(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64)) #define BITS_TO_U32(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32)) #define BITS_TO_BYTES(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char)) +#define BYTES_TO_BITS(nb) ((nb) * BITS_PER_BYTE) + extern unsigned int __sw_hweight8(unsigned int w); extern unsigned int __sw_hweight16(unsigned int w); extern unsigned int __sw_hweight32(unsigned int w); @@ -52,12 +46,17 @@ extern unsigned long __sw_hweight64(__u64 w); __builtin_constant_p(*(const unsigned long *)(addr))) ? \ const##op(nr, addr) : op(nr, addr)) +/* + * The following macros are non-atomic versions of their non-underscored + * counterparts. + */ #define __set_bit(nr, addr) bitop(___set_bit, nr, addr) #define __clear_bit(nr, addr) bitop(___clear_bit, nr, addr) #define __change_bit(nr, addr) bitop(___change_bit, nr, addr) #define __test_and_set_bit(nr, addr) bitop(___test_and_set_bit, nr, addr) #define __test_and_clear_bit(nr, addr) bitop(___test_and_clear_bit, nr, addr) #define __test_and_change_bit(nr, addr) bitop(___test_and_change_bit, nr, addr) + #define test_bit(nr, addr) bitop(_test_bit, nr, addr) #define test_bit_acquire(nr, addr) bitop(_test_bit_acquire, nr, addr) @@ -80,6 +79,7 @@ __check_bitop_pr(__test_and_set_bit); __check_bitop_pr(__test_and_clear_bit); __check_bitop_pr(__test_and_change_bit); __check_bitop_pr(test_bit); +__check_bitop_pr(test_bit_acquire); #undef __check_bitop_pr @@ -200,7 +200,7 @@ static __always_inline __s64 sign_extend64(__u64 value, int index) return (__s64)(value << shift) >> shift; } -static inline unsigned fls_long(unsigned long l) +static inline unsigned int fls_long(unsigned long l) { if (sizeof(l) == 4) return fls(l); @@ -229,6 +229,37 @@ static inline int get_count_order_long(unsigned long l) } /** + * parity8 - get the parity of an u8 value + * @value: the value to be examined + * + * Determine the parity of the u8 argument. + * + * Returns: + * 0 for even parity, 1 for odd parity + * + * Note: This function informs you about the current parity. Example to bail + * out when parity is odd: + * + * if (parity8(val) == 1) + * return -EBADMSG; + * + * If you need to calculate a parity bit, you need to draw the conclusion from + * this result yourself. Example to enforce odd parity, parity bit is bit 7: + * + * if (parity8(val) == 0) + * val ^= BIT(7); + */ +static inline int parity8(u8 val) +{ + /* + * One explanation of this algorithm: + * https://funloop.org/codex/problem/parity/README.html + */ + val ^= val >> 4; + return (0x6996 >> (val & 0xf)) & 1; +} + +/** * __ffs64 - find first set bit in a 64 bit word * @word: The 64 bit word * @@ -236,7 +267,7 @@ static inline int get_count_order_long(unsigned long l) * The result is not defined if no bits are set, so check that @word * is non-zero before calling this. */ -static inline unsigned long __ffs64(u64 word) +static inline unsigned int __ffs64(u64 word) { #if BITS_PER_LONG == 32 if (((u32)word) == 0UL) @@ -252,18 +283,12 @@ static inline unsigned long __ffs64(u64 word) * @word: The word to search * @n: Bit to find */ -static inline unsigned long fns(unsigned long word, unsigned int n) +static inline unsigned int fns(unsigned long word, unsigned int n) { - unsigned int bit; + while (word && n--) + word &= word - 1; - while (word) { - bit = __ffs(word); - if (n-- == 0) - return bit; - __clear_bit(bit, &word); - } - - return BITS_PER_LONG; + return word ? __ffs(word) : BITS_PER_LONG; } /** @@ -272,23 +297,11 @@ static inline unsigned long fns(unsigned long word, unsigned int n) * @addr: the address to start counting from * @value: the value to assign */ -static __always_inline void assign_bit(long nr, volatile unsigned long *addr, - bool value) -{ - if (value) - set_bit(nr, addr); - else - clear_bit(nr, addr); -} +#define assign_bit(nr, addr, value) \ + ((value) ? set_bit((nr), (addr)) : clear_bit((nr), (addr))) -static __always_inline void __assign_bit(long nr, volatile unsigned long *addr, - bool value) -{ - if (value) - __set_bit(nr, addr); - else - __clear_bit(nr, addr); -} +#define __assign_bit(nr, addr, value) \ + ((value) ? __set_bit((nr), (addr)) : __clear_bit((nr), (addr))) /** * __ptr_set_bit - Set bit in a pointer's value |