diff --git a/include/linux/bcd.h b/include/linux/bcd.h
new file mode 100644
index 0000000..18fff11
--- /dev/null
+++ b/include/linux/bcd.h
@@ -0,0 +1,22 @@
+#ifndef _BCD_H
+#define _BCD_H
+
+#include <linux/compiler.h>
+
+#define bcd2bin(x)					\
+		(__builtin_constant_p((u8 )(x)) ?	\
+		const_bcd2bin(x) :			\
+		_bcd2bin(x))
+
+#define bin2bcd(x)					\
+		(__builtin_constant_p((u8 )(x)) ?	\
+		const_bin2bcd(x) :			\
+		_bin2bcd(x))
+
+#define const_bcd2bin(x)	(((x) & 0x0f) + ((x) >> 4) * 10)
+#define const_bin2bcd(x)	((((x) / 10) << 4) + (x) % 10)
+
+unsigned _bcd2bin(unsigned char val) __attribute_const__;
+unsigned char _bin2bcd(unsigned val) __attribute_const__;
+
+#endif /* _BCD_H */
diff --git a/lib/Makefile b/lib/Makefile
index e8769a9..14442a7 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -1,3 +1,4 @@
+obj-y			+= bcd.o
 obj-$(CONFIG_BOOTSTRAP)	+= bootstrap/
 obj-y			+= ctype.o
 obj-y			+= rbtree.o
diff --git a/lib/bcd.c b/lib/bcd.c
new file mode 100644
index 0000000..b072d50
--- /dev/null
+++ b/lib/bcd.c
@@ -0,0 +1,14 @@
+#include <linux/bcd.h>
+#include <module.h>
+
+unsigned _bcd2bin(unsigned char val)
+{
+	return (val & 0x0f) + (val >> 4) * 10;
+}
+EXPORT_SYMBOL(_bcd2bin);
+
+unsigned char _bin2bcd(unsigned val)
+{
+	return ((val / 10) << 4) + val % 10;
+}
+EXPORT_SYMBOL(_bin2bcd);