Add byteswap.h, per glibc

include/byteswap.h

@@ -0,0 +1,40 @@
+/* Copyright (C) 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef _BYTESWAP_H
+#define _BYTESWAP_H	1
+
+/* Get the machine specific, optimized definitions.  */
+#include <bits/byteswap.h>
+
+
+/* The following definitions must all be macros since otherwise some
+   of the possible optimizations are not possible.  */
+
+/* Return a value with all bytes in the 16 bit argument swapped.  */
+#define bswap_16(x) __bswap_16 (x)
+
+/* Return a value with all bytes in the 32 bit argument swapped.  */
+#define bswap_32(x) __bswap_32 (x)
+
+#if defined __GNUC__ && __GNUC__ >= 2
+/* Return a value with all bytes in the 64 bit argument swapped.  */
+# define bswap_64(x) __bswap_64 (x)
+#endif
+
+#endif /* byteswap.h */