[PATCH 05/12] lib: introduce common method to convert hex digits

[Andy Shevchenko <andy.shevchenko@gmail.com>]

From: Andy Shevchenko <ext-andriy.shevchenko@nokia.com>

hex_to_bin() is a little method which converts hex digit to its actual value.
There are plenty of places where such functionality is needed.

Signed-off-by: Andy Shevchenko <ext-andriy.shevchenko@nokia.com>
---
 include/linux/kernel.h |    2 ++
 lib/hexdump.c          |   19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 328bca6..bbbf885 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -361,6 +361,8 @@ static inline char *pack_hex_byte(char *buf, u8 byte)
 	return buf;
 }
 
+extern int hex_to_bin(char ch);
+
 #ifndef pr_fmt
 #define pr_fmt(fmt) fmt
 #endif
diff --git a/lib/hexdump.c b/lib/hexdump.c
index 39af256..d79b166 100644
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -16,6 +16,25 @@ const char hex_asc[] = "0123456789abcdef";
 EXPORT_SYMBOL(hex_asc);
 
 /**
+ * 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 >= 'a') && (ch <= 'f'))
+		return ch - 'a' + 10;
+	if ((ch >= '0') && (ch <= '9'))
+		return ch - '0';
+	if ((ch >= 'A') && (ch <= 'F'))
+		return ch - 'A' + 10;
+	return -1;
+}
+EXPORT_SYMBOL(hex_to_bin);
+
+/**
  * hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory
  * @buf: data blob to dump
  * @len: number of bytes in the @buf
-- 
1.5.6.5