linux-kernel - [PATCH] lib/vsprintf.c: Add %pMF to format FDDI bit reversed MAC addresses

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Message-ID: <1262888625.10429.23.camel@Joe-Laptop.home>
Date:	Thu, 07 Jan 2010 10:23:45 -0800
From:	Joe Perches <joe@...ches.com>
To:	H Hartley Sweeten <hartleys@...ionengravers.com>
Cc:	David Miller <davem@...emloft.net>,
	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	linux-kernel@...r.kernel.org, netdev <netdev@...r.kernel.org>
Subject: [PATCH] lib/vsprintf.c: Add %pMF to format FDDI bit reversed MAC
 addresses

On Mon, 2010-01-04 at 23:43 +0000, Maciej W. Rozycki wrote:
> The example below shows an address, and the sequence of bits or symbols 
> that would be transmitted when the address is used in the Source Address 
> or Destination Address fields on the MAC header.  The transmission line 
> shows the address bits in the order transmitted, from left to right.  For 
> IEEE 802 LANs these correspond to actual bits on the medium.  The FDDI 
> symbols line shows how the FDDI PHY sends the address bits as encoded 
> symbols.
> 
>         MSB:            35:7B:12:00:00:01
>         Canonical:      AC-DE-48-00-00-80
>         Transmission:   00110101 01111011 00010010 00000000 00000000 00000001
>         FDDI Symbols:   35 7B 12 00 00 01"
> 
> Please note that this address has its group bit clear.
> 
>  This notation is also defined in the "FDDI MEDIA ACCESS CONTROL-2 
> (MAC-2)" (X3T9/92-120) document although that book does not have a need 
> to use the MSB form and it's skipped.

Adds 56 bytes to object size

New:
$ size lib/vsprintf.o
   text	   data	    bss	    dec	    hex	filename
   8714	      0	      2	   8716	   220c	lib/vsprintf.o
old:
$ size lib/vsprintf.o
   text	   data	    bss	    dec	    hex	filename
   8658	      0	      2	   8660	   21d4	lib/vsprintf.o

Signed-off-by: Joe Perches <joe@...ches.com>
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index d4996cf..36959cc 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -25,6 +25,7 @@
 #include <linux/kallsyms.h>
 #include <linux/uaccess.h>
 #include <linux/ioport.h>
+#include <linux/bitrev.h>
 #include <net/addrconf.h>
 
 #include <asm/page.h>		/* for PAGE_SIZE */
@@ -675,17 +676,37 @@ static char *resource_string(char *buf, char *end, struct resource *res,
 	return string(buf, end, sym, spec);
 }
 
+static u8 mac_byte(u8 val)
+{
+	return val;
+}
+
+static u8 mac_byte_rev(u8 val)
+{
+	return bitrev8(val);
+}
+
 static char *mac_address_string(char *buf, char *end, u8 *addr,
 				struct printf_spec spec, const char *fmt)
 {
 	char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];
 	char *p = mac_addr;
 	int i;
+	u8 (*mac_byte_fn)(u8 val);
+	char separator;
+
+	if (fmt[1] == 'F') {		/* FDDI canonical format */
+		mac_byte_fn = mac_byte_rev;
+		separator = '-';
+	} else {
+		mac_byte_fn = mac_byte;
+		separator  = ':';
+	}
 
 	for (i = 0; i < 6; i++) {
-		p = pack_hex_byte(p, addr[i]);
+		p = pack_hex_byte(p, mac_byte_fn(addr[i]));
 		if (fmt[0] == 'M' && i != 5)
-			*p++ = ':';
+			*p++ = separator;
 	}
 	*p = '\0';
 
@@ -896,6 +917,10 @@ static char *uuid_string(char *buf, char *end, const u8 *addr,
  * - 'M' For a 6-byte MAC address, it prints the address in the
  *       usual colon-separated hex notation
  * - 'm' For a 6-byte MAC address, it prints the hex address without colons
+ * - 'MF' For a 6-byte MAC FDDI address, it prints the address
+ *       with a dash-separated hex notation with bit reversed bytes
+ * - 'mF' For a 6-byte MAC FDDI address, it prints the address
+ *       in hex notation without separators with bit reversed bytes
  * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way
  *       IPv4 uses dot-separated decimal without leading 0's (1.2.3.4)
  *       IPv6 uses colon separated network-order 16 bit hex with leading 0's
@@ -939,6 +964,7 @@ static char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 		return resource_string(buf, end, ptr, spec, fmt);
 	case 'M':			/* Colon separated: 00:01:02:03:04:05 */
 	case 'm':			/* Contiguous: 000102030405 */
+					/* [mM]F (FDDI, bit reversed) */
 		return mac_address_string(buf, end, ptr, spec, fmt);
 	case 'I':			/* Formatted IP supported
 					 * 4:	1.2.3.4


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