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From: Yu-Jen Chang <arthurchang09@gmail.com>
To: andy@kernel.org, akinobu.mita@gmail.com
Cc: jserv@ccns.ncku.edu.tw, linux-kernel@vger.kernel.org,
	Yu-Jen Chang <arthurchang09@gmail.com>
Subject: [PATCH 1/2] lib/string.c: Add a macro for memchr_inv()
Date: Sun, 10 Jul 2022 22:28:21 +0800	[thread overview]
Message-ID: <20220710142822.52539-2-arthurchang09@gmail.com> (raw)
In-Reply-To: <20220710142822.52539-1-arthurchang09@gmail.com>

We add a macro MEMCHR_MASK_GEN() so that both memchr_inv()
and memchr() can use it to generate a 8 bytes mask.

Signed-off-by: Yu-Jen Chang <arthurchang09@gmail.com>
Signed-off-by: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
---
 lib/string.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/lib/string.c b/lib/string.c
index 485777c9d..80469e6c3 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -879,6 +879,29 @@ char *strnstr(const char *s1, const char *s2, size_t len)
 EXPORT_SYMBOL(strnstr);
 #endif
 
+#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
+
+#define MEMCHR_MASK_GEN(mask) (mask *= 0x0101010101010101ULL)
+
+#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
+
+#define MEMCHR_MASK_GEN(mask)                                                  \
+	do {                                                                   \
+		mask *= 0x01010101;                                            \
+		mask |= mask << 32;                                            \
+	} while (0)
+
+#else
+
+#define MEMCHR_MASK_GEN(mask)                                                  \
+	do {                                                                   \
+		mask |= mask << 8;                                             \
+		mask |= mask << 16;                                            \
+		mask |= mask << 32;                                            \
+	} while (0)
+
+#endif
+
 #ifndef __HAVE_ARCH_MEMCHR
 /**
  * memchr - Find a character in an area of memory.
@@ -932,16 +955,7 @@ void *memchr_inv(const void *start, int c, size_t bytes)
 		return check_bytes8(start, value, bytes);
 
 	value64 = value;
-#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
-	value64 *= 0x0101010101010101ULL;
-#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
-	value64 *= 0x01010101;
-	value64 |= value64 << 32;
-#else
-	value64 |= value64 << 8;
-	value64 |= value64 << 16;
-	value64 |= value64 << 32;
-#endif
+	MEMCHR_MASK_GEN(value64);
 
 	prefix = (unsigned long)start % 8;
 	if (prefix) {
-- 
2.25.1


  reply	other threads:[~2022-07-10 14:28 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-10 14:28 [PATCH 0/2] Optimize memchr() Yu-Jen Chang
2022-07-10 14:28 ` Yu-Jen Chang [this message]
2022-07-10 14:28 ` [PATCH 2/2] lib/string.c: " Yu-Jen Chang
2022-07-10 15:16   ` Joe Perches
2022-07-11 14:50     ` Yu-Jen Chang
2022-07-10 16:58   ` kernel test robot
2022-07-10 20:01   ` Andrey Semashev
2022-07-11 14:52     ` Yu-Jen Chang
2022-07-11 15:00       ` Andrey Semashev
2022-07-11 15:03         ` Andy Shevchenko
2022-07-12 14:58         ` Yu-Jen Chang
2022-07-12 15:08           ` Andy Shevchenko
2022-07-13  9:39           ` David Laight
2022-07-13  9:49             ` Andrey Semashev
2022-07-13 10:02               ` Andrey Semashev
2022-07-13 10:24                 ` David Laight
2022-07-22 16:08                   ` Yu-Jen Chang
     [not found]                     ` <CAHp75Vfy6wYqzT-T9aEjVEAQCZ_k=0qN8S8OwG3knbrC-oOkMQ@mail.gmail.com>
2022-07-29 15:42                       ` Yu-Jen Chang
2022-07-13  9:57             ` Andrey Semashev
2022-07-21  5:06   ` kernel test robot
2022-08-12 19:06 ` [PATCH 0/2] " Pavel Machek
2022-08-15 10:59   ` David Laight

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