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, 8 insertions, 40 deletions

diff --git a/libc/sysdeps/linux/v850/bits/byteswap.h b/libc/sysdeps/linux/v850/bits/byteswap.h
index 44fbee488..b2e1ddb90 100644
--- a/libc/sysdeps/linux/v850/bits/byteswap.h
+++ b/libc/sysdeps/linux/v850/bits/byteswap.h
@@ -11,53 +11,21 @@
  * directory of this archive for more details.
  */
 
-#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.  */
-#define __bswap_constant_16(x) \
-  ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
+#ifndef _ASM_BITS_BYTESWAP_H
+#define _ASM_BITS_BYTESWAP_H 1
 
-#ifdef __GNUC__
-# define __bswap_16(x)							      \
+#define __bswap_non_constant_16(x) \
     (__extension__							      \
      ({ unsigned long int __bswap_16_v;					      \
-        if (__builtin_constant_p (x))					      \
-          __bswap_16_v = __bswap_constant_16 (x);			      \
-        else								      \
-	  __asm__ ("bsh %1, %0" : "=r" (__bswap_16_v) : "r" (x));	      \
+	__asm__ ("bsh %1, %0" : "=r" (__bswap_16_v) : "r" (x));		      \
 	__bswap_16_v; }))
-#else
-# define __bswap_16(x) __bswap_constant_16 (x)
-#endif
 
-/* Swap bytes in 32 bit value.  */
-#define __bswap_constant_32(x) \
-  ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
-   (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
-
-#ifdef __GNUC__
-# define __bswap_32(x)							      \
+# define __bswap_non_constant_32(x) \
     (__extension__							      \
      ({ unsigned long int __bswap_32_v;					      \
-        if (__builtin_constant_p (x))					      \
-          __bswap_32_v = __bswap_constant_32 (x);			      \
-        else								      \
-	  __asm__ ("bsw %1, %0" : "=r" (__bswap_32_v) : "r" (x));	      \
+	__asm__ ("bsw %1, %0" : "=r" (__bswap_32_v) : "r" (x));		      \
 	__bswap_32_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]; } __bswap_64_v, __bswap_64_r;      \
-	 __bswap_64_v.__ll = (x);					      \
-	 __bswap_64_r.__l[0] = __bswap_32 (__bswap_64_v.__l[1]);	      \
-	 __bswap_64_r.__l[1] = __bswap_32 (__bswap_64_v.__l[0]);	      \
-	 __bswap_64_r.__ll; }))
 #endif
+
+#include <bits/byteswap-common.h>