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Message-Id: <1467216957-58885-1-git-send-email-zengzhaoxiu@163.com>
Date: Thu, 30 Jun 2016 00:15:54 +0800
From: zengzhaoxiu@....com
To: linux-kernel@...r.kernel.org
Cc: Zhaoxiu Zeng <zhaoxiu.zeng@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>,
Michal Nazarewicz <mina86@...a86.com>,
Borislav Petkov <bp@...e.de>, Michal Hocko <mhocko@...e.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Nicolas Iooss <nicolas.iooss_linux@....org>,
"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Horacio Mijail Anton Quiles <hmijail@...il.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH 1/2] lib: hexdump: use a look-up table to do hex_to_bin
From: Zhaoxiu Zeng <zhaoxiu.zeng@...il.com>
Signed-off-by: Zhaoxiu Zeng <zhaoxiu.zeng@...il.com>
---
include/linux/kernel.h | 15 ++++++++++++++-
lib/hexdump.c | 36 +++++++++++++++++++-----------------
2 files changed, 33 insertions(+), 18 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 94aa10f..72a0432 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -532,7 +532,20 @@ static inline char *hex_byte_pack_upper(char *buf, u8 byte)
return buf;
}
-extern int hex_to_bin(char ch);
+extern const int8_t h2b_lut[];
+
+/**
+ * hex_to_bin - convert a hex digit to its real value
+ * @ch: ascii character represents hex digit
+ *
+ * hex_to_bin() converts one hex digit to its actual value or -1 in case of bad
+ * input.
+ */
+static inline int hex_to_bin(char ch)
+{
+ return h2b_lut[(unsigned char)ch];
+}
+
extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
extern char *bin2hex(char *dst, const void *src, size_t count);
diff --git a/lib/hexdump.c b/lib/hexdump.c
index 992457b..878697f 100644
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -18,23 +18,25 @@ EXPORT_SYMBOL(hex_asc);
const char hex_asc_upper[] = "0123456789ABCDEF";
EXPORT_SYMBOL(hex_asc_upper);
-/**
- * hex_to_bin - convert a hex digit to its real value
- * @ch: ascii character represents hex digit
- *
- * hex_to_bin() converts one hex digit to its actual value or -1 in case of bad
- * input.
- */
-int hex_to_bin(char ch)
-{
- if ((ch >= '0') && (ch <= '9'))
- return ch - '0';
- ch = tolower(ch);
- if ((ch >= 'a') && (ch <= 'f'))
- return ch - 'a' + 10;
- return -1;
-}
-EXPORT_SYMBOL(hex_to_bin);
+const int8_t h2b_lut[] = {
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
+ -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+};
+EXPORT_SYMBOL(h2b_lut);
/**
* hex2bin - convert an ascii hexadecimal string to its binary representation
--
2.7.4
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