From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f50.google.com (mail-pa0-f50.google.com [209.85.220.50]) by kanga.kvack.org (Postfix) with ESMTP id B74DB280022 for ; Fri, 31 Oct 2014 01:40:30 -0400 (EDT) Received: by mail-pa0-f50.google.com with SMTP id eu11so7067217pac.9 for ; Thu, 30 Oct 2014 22:40:30 -0700 (PDT) Received: from cnbjrel02.sonyericsson.com (cnbjrel02.sonyericsson.com. [219.141.167.166]) by mx.google.com with ESMTPS id fn9si8367892pdb.160.2014.10.30.22.40.26 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 30 Oct 2014 22:40:29 -0700 (PDT) From: "Wang, Yalin" Date: Fri, 31 Oct 2014 13:40:20 +0800 Subject: [RFC V6 1/3] add CONFIG_HAVE_ARCH_BITREVERSE to support rbit instruction Message-ID: <35FD53F367049845BC99AC72306C23D103E010D18272@CNBJMBX05.corpusers.net> References: <1414392371.8884.2.camel@perches.com> <35FD53F367049845BC99AC72306C23D103E010D1825F@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18260@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18261@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18264@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18265@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18266@CNBJMBX05.corpusers.net> <20141030120127.GC32589@arm.com> <20141030135749.GE32589@arm.com> In-Reply-To: <20141030135749.GE32589@arm.com> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: 'Will Deacon' , Ard Biesheuvel Cc: Russell King - ARM Linux , "linux-kernel@vger.kernel.org" , "akinobu.mita@gmail.com" , "linux-mm@kvack.org" , Joe Perches , "linux-arm-kernel@lists.infradead.org" this change add CONFIG_HAVE_ARCH_BITREVERSE config option, so that we can use some architecture's bitrev hardware instruction to do bitrev operation. Introduce __constant_bitrev* macro for constant bitrev operation. Change __bitrev16() __bitrev32() to be inline function, don't need export symbol for these tiny functions. Signed-off-by: Yalin Wang --- include/linux/bitrev.h | 77 ++++++++++++++++++++++++++++++++++++++++++++++= +--- lib/Kconfig | 9 ++++++ lib/bitrev.c | 17 ++--------- 3 files changed, 84 insertions(+), 19 deletions(-) diff --git a/include/linux/bitrev.h b/include/linux/bitrev.h index 7ffe03f..fb790b8 100644 --- a/include/linux/bitrev.h +++ b/include/linux/bitrev.h @@ -3,14 +3,83 @@ =20 #include =20 -extern u8 const byte_rev_table[256]; +#ifdef CONFIG_HAVE_ARCH_BITREVERSE +#include + +#define __bitrev32 __arch_bitrev32 +#define __bitrev16 __arch_bitrev16 +#define __bitrev8 __arch_bitrev8 =20 -static inline u8 bitrev8(u8 byte) +#else +extern u8 const byte_rev_table[256]; +static inline u8 __bitrev8(u8 byte) { return byte_rev_table[byte]; } =20 -extern u16 bitrev16(u16 in); -extern u32 bitrev32(u32 in); +static inline u16 __bitrev16(u16 x) +{ + return (__bitrev8(x & 0xff) << 8) | __bitrev8(x >> 8); +} + +static inline u32 __bitrev32(u32 x) +{ + return (__bitrev16(x & 0xffff) << 16) | __bitrev16(x >> 16); +} + +#endif /* CONFIG_HAVE_ARCH_BITREVERSE */ + +#define __constant_bitrev32(x) \ +({ \ + u32 __x =3D x; \ + __x =3D (__x >> 16) | (__x << 16); \ + __x =3D ((__x & (u32)0xFF00FF00UL) >> 8) | ((__x & (u32)0x00FF00FFUL) << = 8); \ + __x =3D ((__x & (u32)0xF0F0F0F0UL) >> 4) | ((__x & (u32)0x0F0F0F0FUL) << = 4); \ + __x =3D ((__x & (u32)0xCCCCCCCCUL) >> 2) | ((__x & (u32)0x33333333UL) << = 2); \ + __x =3D ((__x & (u32)0xAAAAAAAAUL) >> 1) | ((__x & (u32)0x55555555UL) << = 1); \ + __x; \ +}) + +#define __constant_bitrev16(x) \ +({ \ + u16 __x =3D x; \ + __x =3D (__x >> 8) | (__x << 8); \ + __x =3D ((__x & (u16)0xF0F0U) >> 4) | ((__x & (u16)0x0F0FU) << 4); \ + __x =3D ((__x & (u16)0xCCCCU) >> 2) | ((__x & (u16)0x3333U) << 2); \ + __x =3D ((__x & (u16)0xAAAAU) >> 1) | ((__x & (u16)0x5555U) << 1); \ + __x; \ +}) + +#define __constant_bitrev8(x) \ +({ \ + u8 __x =3D x; \ + __x =3D (__x >> 4) | (__x << 4); \ + __x =3D ((__x & (u8)0xCCU) >> 2) | ((__x & (u8)0x33U) << 2); \ + __x =3D ((__x & (u8)0xAAU) >> 1) | ((__x & (u8)0x55U) << 1); \ + __x; \ +}) + +#define bitrev32(x) \ +({ \ + u32 __x =3D x; \ + __builtin_constant_p(__x) ? \ + __constant_bitrev32(__x) : \ + __bitrev32(__x); \ +}) + +#define bitrev16(x) \ +({ \ + u16 __x =3D x; \ + __builtin_constant_p(__x) ? \ + __constant_bitrev16(__x) : \ + __bitrev16(__x); \ + }) =20 +#define bitrev8(x) \ +({ \ + u8 __x =3D x; \ + __builtin_constant_p(__x) ? \ + __constant_bitrev8(__x) : \ + __bitrev8(__x) ; \ + }) #endif /* _LINUX_BITREV_H */ diff --git a/lib/Kconfig b/lib/Kconfig index 54cf309..cd177ca 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -13,6 +13,15 @@ config RAID6_PQ config BITREVERSE tristate =20 +config HAVE_ARCH_BITREVERSE + boolean + default n + depends on BITREVERSE + help + This option provides an config for the architecture which have instruct= ion + can do bitreverse operation, we use the hardware instruction if the arc= hitecture + have this capability. + config RATIONAL boolean =20 diff --git a/lib/bitrev.c b/lib/bitrev.c index 3956203..40ffda9 100644 --- a/lib/bitrev.c +++ b/lib/bitrev.c @@ -1,3 +1,4 @@ +#ifndef CONFIG_HAVE_ARCH_BITREVERSE #include #include #include @@ -42,18 +43,4 @@ const u8 byte_rev_table[256] =3D { }; EXPORT_SYMBOL_GPL(byte_rev_table); =20 -u16 bitrev16(u16 x) -{ - return (bitrev8(x & 0xff) << 8) | bitrev8(x >> 8); -} -EXPORT_SYMBOL(bitrev16); - -/** - * bitrev32 - reverse the order of bits in a u32 value - * @x: value to be bit-reversed - */ -u32 bitrev32(u32 x) -{ - return (bitrev16(x & 0xffff) << 16) | bitrev16(x >> 16); -} -EXPORT_SYMBOL(bitrev32); +#endif /* CONFIG_HAVE_ARCH_BITREVERSE */ --=20 2.1.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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