byteswap: unify common definitions

The majority of the byteswap functions are the same across all arches, so
setup a common header to provide definitions if they don't exist.  This
allows arches to override only the ones they actually want to implement
with inline assembly.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 108 insertions, 0 deletions

diff --git a/libc/sysdeps/linux/common/bits/byteswap-common.h b/libc/sysdeps/linux/common/bits/byteswap-common.h
new file mode 100644
index 000000000..8586ed008
--- /dev/null
+++ b/libc/sysdeps/linux/common/bits/byteswap-common.h
@@ -0,0 +1,108 @@
+/* Macros to swap the order of bytes in integer values.
+   Copyright (C) 1997,1998,2000,2001,2002,2005 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.  */
+
+#if !defined _BYTESWAP_H && !defined _NETINET_IN_H
+# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
+#endif
+
+#ifndef _BITS_BYTESWAP_H
+#define _BITS_BYTESWAP_H 1
+
+/* Swap bytes in 16 bit value.  */
+#define __bswap_constant_16(x) \
+     ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
+
+#ifndef __bswap_non_constant_16
+# define __bswap_non_constant_16(x) __bswap_constant_16(x)
+#endif
+#ifdef __GNUC__
+# define __bswap_16(x) \
+    (__extension__							      \
+     ({ unsigned short int __bsv, __bsx = (x);				      \
+	if (__builtin_constant_p (__bsx))				      \
+	  __bsv = __bswap_constant_16 (__bsx);				      \
+	else								      \
+	  __bsv = __bswap_non_constant_16 (__bsx);			      \
+	__bsv; }))
+#else
+static __inline unsigned short int
+__bswap_16 (unsigned short int __bsx)
+{
+  return __bswap_constant_16 (__bsx);
+}
+#endif
+
+/* Swap bytes in 32 bit value.  */
+#define __bswap_constant_32(x) \
+     ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >>  8) |	      \
+      (((x) & 0x0000ff00u) <<  8) | (((x) & 0x000000ffu) << 24))
+
+#ifndef __bswap_non_constant_32
+# define __bswap_non_constant_32(x) __bswap_constant_32(x)
+#endif
+#ifdef __GNUC__
+# define __bswap_32(x) \
+    (__extension__							      \
+     ({ unsigned int __bsv, __bsx = (x);				      \
+	if (__builtin_constant_p (__bsx))				      \
+	  __bsv = __bswap_constant_32 (__bsx);				      \
+	else								      \
+	  __bsv = __bswap_non_constant_32 (__bsx);			      \
+	__bsv; }))
+#else
+static __inline unsigned int
+__bswap_32 (unsigned int __bsx)
+{
+  return __bswap_constant_32 (__bsx);
+}
+#endif
+
+#if defined __GNUC__ && __GNUC__ >= 2
+/* Swap bytes in 64 bit value.  */
+# define __bswap_constant_64(x) \
+     ((((x) & 0xff00000000000000ull) >> 56)				      \
+      | (((x) & 0x00ff000000000000ull) >> 40)				      \
+      | (((x) & 0x0000ff0000000000ull) >> 24)				      \
+      | (((x) & 0x000000ff00000000ull) >> 8)				      \
+      | (((x) & 0x00000000ff000000ull) << 8)				      \
+      | (((x) & 0x0000000000ff0000ull) << 24)				      \
+      | (((x) & 0x000000000000ff00ull) << 40)				      \
+      | (((x) & 0x00000000000000ffull) << 56))
+
+# ifndef __bswap_non_constant_64
+#  define __bswap_non_constant_64(x) \
+     (__extension__							      \
+      ({ union { __extension__ unsigned long long int __ll;		      \
+		 unsigned int __l[2]; } __w, __r;			      \
+	 __w.__ll = (x);						      \
+	 __r.__l[0] = __bswap_non_constant_32 (__w.__l[1]);		      \
+	 __r.__l[1] = __bswap_non_constant_32 (__w.__l[0]);		      \
+	 __r.__ll; }))
+# endif
+# define __bswap_64(x) \
+     (__extension__							      \
+      ({ __extension__ unsigned long long int __ll;			      \
+         if (__builtin_constant_p (x))					      \
+	   __ll = __bswap_constant_64 (x);				      \
+	 else								      \
+	   __ll = __bswap_non_constant_64 (x);				      \
+	 __ll; }))
+#endif
+
+#endif /* _BITS_BYTESWAP_H */