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Message-ID: <57334287.6040208@posteo.de>
Date: Wed, 11 May 2016 16:32:39 +0200
From: Martin Kepplinger <martink@...teo.de>
To: zengzhaoxiu@....com, linux-kernel@...r.kernel.org,
linux@...izon.com, ulrik.debie-os@...ig.org
Cc: Zhaoxiu Zeng <zhaoxiu.zeng@...il.com>,
Arnd Bergmann <arnd@...db.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Sasha Levin <sasha.levin@...cle.com>,
Ingo Molnar <mingo@...nel.org>,
Denys Vlasenko <dvlasenk@...hat.com>,
linux-arch@...r.kernel.org
Subject: Re: [patch V4 01/31] bitops: add parity functions
Am 2016-05-11 um 10:47 schrieb zengzhaoxiu@....com:
> From: Zhaoxiu Zeng <zhaoxiu.zeng@...il.com>
>
> Add generic parity functions, adapted from
> "https://graphics.stanford.edu/~seander/bithacks.html#ParityParallel".
>
> The function parityN returns whether an odd or even number of bits are on
> in a N-bit word.
>
> Signed-off-by: Zhaoxiu Zeng <zhaoxiu.zeng@...il.com>
> ---
This won't be up to me, but I'd appreciate to see all 31 patches
together without having to look for them; I guess I'm not alone.
thanks
martin
> 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-bits number
> + */
> +#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
>
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