glibc/sysdeps/s390/bits/byteswap-16.h

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/* Macros to swap the order of bytes in 16-bit integer values. s390 version
Copyright (C) 2012-2017 Free Software Foundation, Inc.
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Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
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, see
<http://www.gnu.org/licenses/>. */
#ifndef _BITS_BYTESWAP_H
# error "Never use <bits/byteswap-16.h> directly; include <byteswap.h> instead."
#endif
#include <bits/wordsize.h>
/* Swap bytes in 16 bit value. */
#if defined __GNUC__ && __GNUC__ >= 2
# if __WORDSIZE == 64
# define __bswap_16(x) \
(__extension__ \
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({ unsigned short int __v, __x = (unsigned short int) (x); \
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if (__builtin_constant_p (x)) \
__v = __bswap_constant_16 (__x); \
else { \
unsigned short int __tmp = (unsigned short int) (__x); \
__asm__ __volatile__ ( \
"lrvh %0,%1" \
: "=&d" (__v) : "m" (__tmp) ); \
} \
__v; }))
# else
# define __bswap_16(x) \
(__extension__ \
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({ unsigned short int __v, __x = (unsigned short int) (x); \
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if (__builtin_constant_p (x)) \
__v = __bswap_constant_16 (__x); \
else { \
unsigned short int __tmp = (unsigned short int) (__x); \
__asm__ __volatile__ ( \
"sr %0,%0\n" \
"la 1,%1\n" \
"icm %0,2,1(1)\n" \
"ic %0,0(1)" \
: "=&d" (__v) : "m" (__tmp) : "1"); \
} \
__v; }))
# endif
#else
/* This is better than nothing. */
static __inline unsigned short int
__bswap_16 (unsigned short int __bsx)
{
return __bswap_constant_16 (__bsx);
}
#endif