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, 17 insertions, 44 deletions

diff --git a/libc/sysdeps/linux/h8300/bits/byteswap.h b/libc/sysdeps/linux/h8300/bits/byteswap.h
index dc56467f2..781a4dbfa 100644
--- a/libc/sysdeps/linux/h8300/bits/byteswap.h
+++ b/libc/sysdeps/linux/h8300/bits/byteswap.h
@@ -17,51 +17,24 @@
    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
-
-/* Swap bytes in 16 bit value.  We don't provide an assembler version
-   because GCC is smart enough to generate optimal assembler output, and
-   this allows for better cse.  */
-#define __bswap_16(x) \
-  ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
+#ifndef _ASM_BITS_BYTESWAP_H
+#define _ASM_BITS_BYTESWAP_H 1
 
-/* Swap bytes in 32 bit value.  */
-#define __bswap_constant_32(x) \
-  ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
-   (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
-
-#if defined __GNUC__ && __GNUC__ >= 2
-# define __bswap_32(x) \
-  __extension__					\
-  ({ unsigned int __v;				\
-     if (__builtin_constant_p (x))		\
-       __v = __bswap_constant_32 (x);		\
-     else					\
-       __asm__ __volatile__ ("mov.l %0,er0\n\t"	\
-			     "mov.b r0l,r1h\n\t"	\
-			     "mov.b r0h,r1l\n\t"	\
-			     "mov.w r1,e1\n\t"	\
-			     "mov.w e0,r0\n\t"	\
-			     "mov.b r0l,r1h\n\t"	\
-			     "mov.b r0h,r1l\n\t"	\
-			     "mov.l er1,%0"	\
-			     : "=d" (__v)	\
-			     : "0" (x): "er0","er1");	\
+#define __bswap_non_constant_32(x) \
+  __extension__						\
+  ({ unsigned int __v;					\
+     __asm__ __volatile__ ("mov.l %0,er0\n\t"		\
+			   "mov.b r0l,r1h\n\t"		\
+			   "mov.b r0h,r1l\n\t"		\
+			   "mov.w r1,e1\n\t"		\
+			   "mov.w e0,r0\n\t"		\
+			   "mov.b r0l,r1h\n\t"		\
+			   "mov.b r0h,r1l\n\t"		\
+			   "mov.l er1,%0"		\
+			   : "=d" (__v)			\
+			   : "0" (x): "er0","er1");	\
      __v; })
-#else
-# define __bswap_32(x) __bswap_constant_32 (x)
-#endif
 
-#if defined __GNUC__ && __GNUC__ >= 2
-/* Swap bytes in 64 bit value.  */
-# define __bswap_64(x) \
-  __extension__						\
-  ({ union { unsigned long long int __ll;		\
-	     unsigned long int __l[2]; } __v, __r;	\
-     __v.__ll = (x);					\
-     __r.__l[0] = __bswap_32 (__v.__l[1]);		\
-     __r.__l[1] = __bswap_32 (__v.__l[0]);		\
-     __r.__ll; })
 #endif
+
+#include <bits/byteswap-common.h>