lib: create common ascii hex array

Add a common hex array in hexdump.c so everyone can use it.

Add a common hi/lo helper to avoid the shifting masking that is
done to get the upper and lower nibbles of a byte value.

Pull the pack_hex_byte helper from kgdb as it is opencoded many
places in the tree that will be consolidated.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/hexdump.c b/lib/hexdump.c
index 3435465..f07c0db 100644
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -12,6 +12,9 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 
+const char hex_asc[] = "0123456789abcdef";
+EXPORT_SYMBOL(hex_asc);
+
 /**
  * hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory
  * @buf: data blob to dump
@@ -93,8 +96,8 @@
 		for (j = 0; (j < rowsize) && (j < len) && (lx + 4) < linebuflen;
 		     j++) {
 			ch = ptr[j];
-			linebuf[lx++] = hex_asc(ch >> 4);
-			linebuf[lx++] = hex_asc(ch & 0x0f);
+			linebuf[lx++] = hex_asc_hi(ch);
+			linebuf[lx++] = hex_asc_lo(ch);
 			linebuf[lx++] = ' ';
 		}
 		ascii_column = 3 * rowsize + 2;