linux-kernel - [PATCH v2 2/3] word-at-a-time.h: support zero

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Date:	Tue, 6 Oct 2015 15:23:48 -0400
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	Michael Cree <mcree@...on.net.nz>,
	Matt Turner <mattst88@...il.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Yoshinori Sato <ysato@...rs.sourceforge.jp>,
	Alexey Dobriyan <adobriyan@...il.com>,
	"Rasmus Villemoes" <linux@...musvillemoes.dk>,
	Ingo Molnar <mingo@...nel.org>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	<linux-alpha@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
CC:	Chris Metcalf <cmetcalf@...hip.com>
Subject: [PATCH v2 2/3] word-at-a-time.h: support zero_bytemask() on alpha and tile

Both alpha and tile needed implementations of zero_bytemask.

The alpha version is untested.

Signed-off-by: Chris Metcalf <cmetcalf@...hip.com>
---
 arch/alpha/include/asm/word-at-a-time.h | 2 ++
 arch/tile/include/asm/word-at-a-time.h  | 8 +++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/include/asm/word-at-a-time.h b/arch/alpha/include/asm/word-at-a-time.h
index 6b340d0f1521..902e6ab00a06 100644
--- a/arch/alpha/include/asm/word-at-a-time.h
+++ b/arch/alpha/include/asm/word-at-a-time.h
@@ -52,4 +52,6 @@ static inline unsigned long find_zero(unsigned long bits)
 #endif
 }
 
+#define zero_bytemask(mask) ((2ul << (find_zero(mask) * 8)) - 1)
+
 #endif /* _ASM_WORD_AT_A_TIME_H */
diff --git a/arch/tile/include/asm/word-at-a-time.h b/arch/tile/include/asm/word-at-a-time.h
index 9e5ce0d7b292..b66a693c2c34 100644
--- a/arch/tile/include/asm/word-at-a-time.h
+++ b/arch/tile/include/asm/word-at-a-time.h
@@ -6,7 +6,7 @@
 struct word_at_a_time { /* unused */ };
 #define WORD_AT_A_TIME_CONSTANTS {}
 
-/* Generate 0x01 byte values for non-zero bytes using a SIMD instruction. */
+/* Generate 0x01 byte values for zero bytes using a SIMD instruction. */
 static inline unsigned long has_zero(unsigned long val, unsigned long *data,
 				     const struct word_at_a_time *c)
 {
@@ -33,4 +33,10 @@ static inline long find_zero(unsigned long mask)
 #endif
 }
 
+#ifdef __BIG_ENDIAN
+#define zero_bytemask(mask) (~1ul << (63 - __builtin_clzl(mask)))
+#else
+#define zero_bytemask(mask) ((2ul << __builtin_ctzl(mask)) - 1)
+#endif
+
 #endif /* _ASM_WORD_AT_A_TIME_H */
-- 
2.1.2

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