Add an option to byteswap fields when writing v1 swap header.
Useful for building a TiVo swap header on an i386.

millert@courtesan.com

--- util-linux-2.12/disk-utils/mkswap.c.DIST	2002-10-31 18:52:29.000000000 -0700
+++ util-linux-2.12/disk-utils/mkswap.c	2003-09-27 21:55:36.000000000 -0600
@@ -13,6 +13,7 @@
  *	-c   for readability checking. (Use it unless you are SURE!)
  *	-vN  for swap areas version N. (Only N=0,1 known today.)
  *      -f   for forcing swap creation even if it would smash partition table.
+ *      -S   for doing byteswapping on int-length fields
  *
  * The device may be a block device or an image of one, but this isn't
  * enforced (but it's not much fun on a character device :-).
@@ -26,7 +27,7 @@
  * V1_MAX_PAGES fixes, jj, 990325.
  * sparc64 fixes, jj, 000219.
  *
- * 1999-02-22 Arkadiusz Mi)B¶kiewicz <misiek@pld.ORG.PL>
+ * 1999-02-22 Arkadiusz Mi)B¶kiewicz <misiek@pld.ORG.PL>
  * - added Native Language Support
  * 
  */
@@ -70,6 +71,12 @@
 
 #define MAKE_VERSION(p,q,r)	(65536*(p) + 256*(q) + (r))
 
+#ifndef __bswap_32
+#define __bswap_32(x)							\
+     ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |		\
+      (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
+#endif
+
 static int
 linux_version_code(void) {
 	struct utsname my_utsname;
@@ -323,7 +330,7 @@
 static void
 usage(void) {
 	fprintf(stderr,
-		_("Usage: %s [-c] [-v0|-v1] [-pPAGESZ] /dev/name [blocks]\n"),
+		_("Usage: %s [-c] [-v0|-v1] [-pPAGESZ] [-S] /dev/name [blocks]\n"),
 		program_name);
 	exit(1);
 }
@@ -445,6 +452,7 @@
 	long goodpages;
 	off_t offset;
 	int force = 0;
+	int byteswap = 0;
 	char *block_count = 0;
 	char *pp;
 
@@ -483,6 +491,9 @@
 				case 'v':
 					version = atoi(argv[i]+2);
 					break;
+				case 'S':
+					byteswap = 1;
+					break;
 				default:
 					usage();
 			}
@@ -605,9 +616,15 @@
 	if (version == 0 && !bit_test_and_clear(signature_page,0))
 		die(_("fatal: first page unreadable"));
 	if (version == 1) {
-		p->version = version;
-		p->last_page = PAGES-1;
-		p->nr_badpages = badpages;
+		if (byteswap) {
+			p->version = __bswap_32(version);
+			p->last_page = __bswap_32(PAGES-1);
+			p->nr_badpages = __bswap_32(badpages);
+		} else {
+			p->version = version;
+			p->last_page = PAGES-1;
+			p->nr_badpages = badpages;
+		}
 	}
 
 	goodpages = PAGES - badpages - 1;