From: Zhaoxiu Zeng <zhaoxiu.zeng@xxxxxxxxx> Add generic odd parity functions, adapted from "https://graphics.stanford.edu/~seander/bithacks.html#ParityParallel"; Signed-off-by: Zhaoxiu Zeng <zhaoxiu.zeng@xxxxxxxxx> --- include/asm-generic/bitops.h | 1 + include/asm-generic/bitops/arch_parity.h | 39 +++++++++++++++++++++++++++++++ include/asm-generic/bitops/const_parity.h | 36 ++++++++++++++++++++++++++++ include/asm-generic/bitops/parity.h | 7 ++++++ include/asm-generic/bitops/popc-parity.h | 32 +++++++++++++++++++++++++ include/linux/bitops.h | 10 ++++++++ 6 files changed, 125 insertions(+) create mode 100644 include/asm-generic/bitops/arch_parity.h create mode 100644 include/asm-generic/bitops/const_parity.h create mode 100644 include/asm-generic/bitops/parity.h create mode 100644 include/asm-generic/bitops/popc-parity.h diff --git a/include/asm-generic/bitops.h b/include/asm-generic/bitops.h index dcdcacf..d85722f 100644 --- a/include/asm-generic/bitops.h +++ b/include/asm-generic/bitops.h @@ -27,6 +27,7 @@ #include <asm-generic/bitops/sched.h> #include <asm-generic/bitops/ffs.h> #include <asm-generic/bitops/hweight.h> +#include <asm-generic/bitops/parity.h> #include <asm-generic/bitops/lock.h> #include <asm-generic/bitops/atomic.h> diff --git a/include/asm-generic/bitops/arch_parity.h b/include/asm-generic/bitops/arch_parity.h new file mode 100644 index 0000000..813e152 --- /dev/null +++ b/include/asm-generic/bitops/arch_parity.h @@ -0,0 +1,39 @@ +#ifndef _ASM_GENERIC_BITOPS_ARCH_PARITY_H_ +#define _ASM_GENERIC_BITOPS_ARCH_PARITY_H_ + +#include <asm/types.h> + +/* + * Refrence to 'https://graphics.stanford.edu/~seander/bithacks.html#ParityParallel'. + */ + +static inline unsigned int __arch_parity4(unsigned int w) +{ + w &= 0xf; + return ((PARITY_MAGIC) >> w) & 1; +} + +static inline unsigned int __arch_parity8(unsigned int w) +{ + w ^= w >> 4; + return __arch_parity4(w); +} + +static inline unsigned int __arch_parity16(unsigned int w) +{ + w ^= w >> 8; + return __arch_parity8(w); +} + +static inline unsigned int __arch_parity32(unsigned int w) +{ + w ^= w >> 16; + return __arch_parity16(w); +} + +static inline unsigned int __arch_parity64(__u64 w) +{ + return __arch_parity32((unsigned int)(w >> 32) ^ (unsigned int)w); +} + +#endif /* _ASM_GENERIC_BITOPS_ARCH_PARITY_H_ */ diff --git a/include/asm-generic/bitops/const_parity.h b/include/asm-generic/bitops/const_parity.h new file mode 100644 index 0000000..3970546 --- /dev/null +++ b/include/asm-generic/bitops/const_parity.h @@ -0,0 +1,36 @@ +#ifndef _ASM_GENERIC_BITOPS_CONST_PARITY_H_ +#define _ASM_GENERIC_BITOPS_CONST_PARITY_H_ + +/* + * Compile time versions of __arch_parityN() + */ +#define __const_parity4(w) (((PARITY_MAGIC) >> ((w) & 0xf)) & 1) +#define __const_parity8(w) (__const_parity4((w) ^ ((w) >> 4))) +#define __const_parity16(w) (__const_parity8((w) ^ ((w) >> 8))) +#define __const_parity32(w) (__const_parity16((w) ^ ((w) >> 16))) +#define __const_parity64(w) (__const_parity32((w) ^ ((w) >> 32))) + +/* + * Generic interface. + */ +#define parity4(w) (__builtin_constant_p(w) ? __const_parity4(w) : __arch_parity4(w)) +#define parity8(w) (__builtin_constant_p(w) ? __const_parity8(w) : __arch_parity8(w)) +#define parity16(w) (__builtin_constant_p(w) ? __const_parity16(w) : __arch_parity16(w)) +#define parity32(w) (__builtin_constant_p(w) ? __const_parity32(w) : __arch_parity32(w)) +#define parity64(w) (__builtin_constant_p(w) ? __const_parity64(w) : __arch_parity64(w)) + +/* + * Interface for known constant arguments + */ +#define PARITY4(w) (BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) + __const_parity4(w)) +#define PARITY8(w) (BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) + __const_parity8(w)) +#define PARITY16(w) (BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) + __const_parity16(w)) +#define PARITY32(w) (BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) + __const_parity32(w)) +#define PARITY64(w) (BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) + __const_parity64(w)) + +/* + * Type invariant interface to the compile time constant parity functions. + */ +#define PARITY(w) PARITY64((u64)(w)) + +#endif /* _ASM_GENERIC_BITOPS_CONST_PARITY_H_ */ diff --git a/include/asm-generic/bitops/parity.h b/include/asm-generic/bitops/parity.h new file mode 100644 index 0000000..a91dce7 --- /dev/null +++ b/include/asm-generic/bitops/parity.h @@ -0,0 +1,7 @@ +#ifndef _ASM_GENERIC_BITOPS_PARITY_H_ +#define _ASM_GENERIC_BITOPS_PARITY_H_ + +#include <asm-generic/bitops/arch_parity.h> +#include <asm-generic/bitops/const_parity.h> + +#endif /* _ASM_GENERIC_BITOPS_PARITY_H_ */ diff --git a/include/asm-generic/bitops/popc-parity.h b/include/asm-generic/bitops/popc-parity.h new file mode 100644 index 0000000..bf05999 --- /dev/null +++ b/include/asm-generic/bitops/popc-parity.h @@ -0,0 +1,32 @@ +#ifndef _ASM_GENERIC_BITOPS_POPC_PARITY_H_ +#define _ASM_GENERIC_BITOPS_POPC_PARITY_H_ + +#include <asm/types.h> + +static inline unsigned int __arch_parity32(unsigned int w) +{ + return __builtin_popcount(w) & 1; +} + +static inline unsigned int __arch_parity16(unsigned int w) +{ + return __arch_parity32(w & 0xffff); +} + +static inline unsigned int __arch_parity8(unsigned int w) +{ + return __arch_parity32(w & 0xff); +} + +static inline unsigned int __arch_parity4(unsigned int w) +{ + return __arch_parity32(w & 0xf); +} + +static inline unsigned int __arch_parity64(__u64 w) +{ + return (unsigned int)__builtin_popcountll(w) & 1; +} + +#endif + diff --git a/include/linux/bitops.h b/include/linux/bitops.h index defeaac..c3ea19e 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -30,6 +30,11 @@ extern unsigned int __sw_hweight32(unsigned int w); extern unsigned long __sw_hweight64(__u64 w); /* + * a miniature 16-bit parity-table of 4-bit numbers + */ +#define PARITY_MAGIC 0x6996 + +/* * Include this here because some architectures need generic_ffs/fls in * scope */ @@ -80,6 +85,11 @@ static __always_inline unsigned long hweight_long(unsigned long w) return sizeof(w) == 4 ? hweight32(w) : hweight64(w); } +static __always_inline unsigned int parity_long(unsigned long w) +{ + return sizeof(w) == 4 ? parity32(w) : parity64(w); +} + /** * rol64 - rotate a 64-bit value left * @word: value to rotate -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
