sysdeps/s390/bits/byteswap-16.h

   1 /* Macros to swap the order of bytes in 16-bit integer values.  s390 version
   2    Copyright (C) 2012-2014 Free Software Foundation, Inc.
   3    Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _BITS_BYTESWAP_H
  21 # error "Never use <bits/byteswap-16.h> directly; include <byteswap.h> instead."
  22 #endif
  23
  24 #include <bits/wordsize.h>
  25
  26 /* Swap bytes in 16 bit value. */
  27 #if defined __GNUC__ && __GNUC__ >= 2
  28 # if __WORDSIZE == 64
  29 #  define __bswap_16(x) \
  30      (__extension__                                                           \
  31       ({ unsigned short int __v, __x = (unsigned short int) (x);              \
  32          if (__builtin_constant_p (x))                                        \
  33            __v = __bswap_constant_16 (__x);                                   \
  34          else {                                                               \
  35            unsigned short int __tmp = (unsigned short int) (__x);             \
  36            __asm__ __volatile__ (                                             \
  37               "lrvh %0,%1"                                                    \
  38               : "=&d" (__v) : "m" (__tmp) );                                  \
  39          }                                                                    \
  40          __v; }))
  41 # else
  42 #  define __bswap_16(x) \
  43      (__extension__                                                           \
  44       ({ unsigned short int __v, __x = (unsigned short int) (x);              \
  45          if (__builtin_constant_p (x))                                        \
  46            __v = __bswap_constant_16 (__x);                                   \
  47          else {                                                               \
  48            unsigned short int __tmp = (unsigned short int) (__x);             \
  49            __asm__ __volatile__ (                                             \
  50               "sr   %0,%0\n"                                                  \
  51               "la   1,%1\n"                                                   \
  52               "icm  %0,2,1(1)\n"                                              \
  53               "ic   %0,0(1)"                                                  \
  54               : "=&d" (__v) : "m" (__tmp) : "1");                             \
  55          }                                                                    \
  56          __v; }))
  57 # endif
  58 #else
  59 /* This is better than nothing.  */
  60 static __inline unsigned short int
  61 __bswap_16 (unsigned short int __bsx)
  62 {
  63   return __bswap_constant_16 (__bsx);
  64 }
  65 #endif