From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joshua Clayton Subject: [PATCH v6 1/5] lib: add bitrev8x4() Date: Fri, 16 Dec 2016 15:17:50 -0800 Message-ID: <3d70fb271f0d2ab2bfbbc60281913bdb3c5f0fb7.1481918884.git.stillcompiling@gmail.com> References: Return-path: In-Reply-To: In-Reply-To: References: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alan Tull , Moritz Fischer , Russell King , Catalin Marinas , Will Deacon , Shawn Guo , Sascha Hauer , Fabio Estevam Cc: Mark Rutland , Rob Herring , Anatolij Gustschin , Joshua Clayton , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-fpga-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Add a function to reverse bytes within a 32 bit word. Operate on a u32 rather than individual bytes. ARCH specific versions require substantially fewer instructions than working a byte at a time. Signed-off-by: Joshua Clayton --- include/linux/bitrev.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/linux/bitrev.h b/include/linux/bitrev.h index fb790b8..868dcb6 100644 --- a/include/linux/bitrev.h +++ b/include/linux/bitrev.h @@ -27,6 +27,14 @@ static inline u32 __bitrev32(u32 x) return (__bitrev16(x & 0xffff) << 16) | __bitrev16(x >> 16); } +static inline u32 __bitrev8x4(u32 x) +{ + return(__bitrev8(x & 0xff) | + (__bitrev8((x >> 8) & 0xff) << 8) | + (__bitrev8((x >> 16) & 0xff) << 16) | + (__bitrev8((x >> 24) & 0xff) << 24)); +} + #endif /* CONFIG_HAVE_ARCH_BITREVERSE */ #define __constant_bitrev32(x) \ @@ -50,6 +58,15 @@ static inline u32 __bitrev32(u32 x) __x; \ }) +#define __constant_bitrev8x4(x) \ +({ \ + u32 __x = x; \ + __x = ((__x & (u32)0xF0F0F0F0UL) >> 4) | ((__x & (u32)0x0F0F0F0FUL) << 4); \ + __x = ((__x & (u32)0xCCCCCCCCUL) >> 2) | ((__x & (u32)0x33333333UL) << 2); \ + __x = ((__x & (u32)0xAAAAAAAAUL) >> 1) | ((__x & (u32)0x55555555UL) << 1); \ + __x; \ +}) + #define __constant_bitrev8(x) \ ({ \ u8 __x = x; \ @@ -75,6 +92,14 @@ static inline u32 __bitrev32(u32 x) __bitrev16(__x); \ }) +#define bitrev8x4(x) \ +({ \ + u32 __x = x; \ + __builtin_constant_p(__x) ? \ + __constant_bitrev8x4(__x) : \ + __bitrev8x4(__x); \ +}) + #define bitrev8(x) \ ({ \ u8 __x = x; \ -- 2.9.3 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html