diff options
Diffstat (limited to 'include/linux/bitops.h')
| -rw-r--r-- | include/linux/bitops.h | 44 |
1 files changed, 40 insertions, 4 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index ba35bbf07798..657eab2725ce 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -8,7 +8,6 @@ #include <uapi/linux/kernel.h> -#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)) @@ -180,9 +179,11 @@ static inline __u8 ror8(__u8 word, unsigned int shift) /** * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit * @value: value to sign extend - * @index: 0 based bit index (0<=index<32) to sign bit + * @index: 0 based bit index (0 <= index < 32) to sign bit * * This is safe to use for 16- and 8-bit types as well. + * + * Return: 32-bit sign extended value */ static __always_inline __s32 sign_extend32(__u32 value, int index) { @@ -193,7 +194,11 @@ static __always_inline __s32 sign_extend32(__u32 value, int index) /** * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit * @value: value to sign extend - * @index: 0 based bit index (0<=index<64) to sign bit + * @index: 0 based bit index (0 <= index < 64) to sign bit + * + * This is safe to use for 32-, 16- and 8-bit types as well. + * + * Return: 64-bit sign extended value */ static __always_inline __s64 sign_extend64(__u64 value, int index) { @@ -230,6 +235,37 @@ static inline int get_count_order_long(unsigned long l) } /** + * parity8 - get the parity of an u8 value + * @val: 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 * @@ -237,7 +273,7 @@ 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 int __ffs64(u64 word) +static inline __attribute_const__ unsigned int __ffs64(u64 word) { #if BITS_PER_LONG == 32 if (((u32)word) == 0UL) |