interpretor/libsndfile-1.0.25/M4/endian.m4

   1 dnl @synopsis MN_C_FIND_ENDIAN
   2 dnl
   3 dnl Determine endian-ness of target processor.
   4 dnl @version 1.1        Mar 03 2002
   5 dnl @author Erik de Castro Lopo <erikd AT mega-nerd DOT com>
   6 dnl
   7 dnl Majority written from scratch to replace the standard autoconf macro
   8 dnl AC_C_BIGENDIAN. Only part remaining from the original it the invocation
   9 dnl of the AC_TRY_RUN macro.
  10 dnl
  11 dnl Permission to use, copy, modify, distribute, and sell this file for any
  12 dnl purpose is hereby granted without fee, provided that the above copyright
  13 dnl and this permission notice appear in all copies.  No representations are
  14 dnl made about the suitability of this software for any purpose.  It is
  15 dnl provided "as is" without express or implied warranty.
  16
  17 dnl Find endian-ness in the following way:
  18 dnl    1) Look in <endian.h>.
  19 dnl    2) If 1) fails, look in <sys/types.h> and <sys/param.h>.
  20 dnl    3) If 1) and 2) fails and not cross compiling run a test program.
  21 dnl    4) If 1) and 2) fails and cross compiling then guess based on target.
  22
  23 AC_DEFUN([MN_C_FIND_ENDIAN],
  24 [AC_CACHE_CHECK(processor byte ordering,
  25         ac_cv_c_byte_order,
  26
  27 # Initialize to unknown
  28 ac_cv_c_byte_order=unknown
  29
  30 if test x$ac_cv_header_endian_h = xyes ; then
  31
  32         # First try <endian.h> which should set BYTE_ORDER.
  33
  34         [AC_TRY_LINK([
  35                 #include <endian.h>
  36                 #if BYTE_ORDER != LITTLE_ENDIAN
  37                         not big endian
  38                 #endif
  39                 ], return 0 ;,
  40                         ac_cv_c_byte_order=little
  41                 )]
  42
  43         [AC_TRY_LINK([
  44                 #include <endian.h>
  45                 #if BYTE_ORDER != BIG_ENDIAN
  46                         not big endian
  47                 #endif
  48                 ], return 0 ;,
  49                         ac_cv_c_byte_order=big
  50                 )]
  51
  52         fi
  53
  54 if test $ac_cv_c_byte_order = unknown ; then
  55
  56         [AC_TRY_LINK([
  57                 #include <sys/types.h>
  58                 #include <sys/param.h>
  59                 #if !BYTE_ORDER || !BIG_ENDIAN || !LITTLE_ENDIAN
  60                         bogus endian macros
  61                 #endif
  62                 ], return 0 ;,
  63
  64                 [AC_TRY_LINK([
  65                         #include <sys/types.h>
  66                         #include <sys/param.h>
  67                         #if BYTE_ORDER != LITTLE_ENDIAN
  68                                 not big endian
  69                         #endif
  70                         ], return 0 ;,
  71                                 ac_cv_c_byte_order=little
  72                         )]
  73
  74                 [AC_TRY_LINK([
  75                         #include <sys/types.h>
  76                         #include <sys/param.h>
  77                         #if BYTE_ORDER != LITTLE_ENDIAN
  78                                 not big endian
  79                         #endif
  80                         ], return 0 ;,
  81                                 ac_cv_c_byte_order=little
  82                         )]
  83
  84                 )]
  85
  86         fi
  87
  88 if test $ac_cv_c_byte_order = unknown ; then
  89         if test $cross_compiling = yes ; then
  90                 # This is the last resort. Try to guess the target processor endian-ness
  91                 # by looking at the target CPU type.
  92                 [
  93                 case "$target_cpu" in
  94                         alpha* | i?86* | mipsel* | ia64*)
  95                                 ac_cv_c_byte_order=little
  96                                 ;;
  97
  98                         m68* | mips* | powerpc* | hppa* | sparc*)
  99                                 ac_cv_c_byte_order=big
 100                                 ;;
 101
 102                         esac
 103                 ]
 104         else
 105                 AC_TRY_RUN(
 106                 [[
 107                 int main (void)
 108                 {       /* Are we little or big endian?  From Harbison&Steele.  */
 109                         union
 110                         {       long l ;
 111                                 char c [sizeof (long)] ;
 112                         } u ;
 113                         u.l = 1 ;
 114                         return (u.c [sizeof (long) - 1] == 1);
 115                         }
 116                         ]], , ac_cv_c_byte_order=big,
 117                         )
 118
 119                 AC_TRY_RUN(
 120                 [[int main (void)
 121                 {       /* Are we little or big endian?  From Harbison&Steele.  */
 122                         union
 123                         {       long l ;
 124                                 char c [sizeof (long)] ;
 125                         } u ;
 126                         u.l = 1 ;
 127                         return (u.c [0] == 1);
 128                         }]], , ac_cv_c_byte_order=little,
 129                         )
 130                 fi
 131         fi
 132
 133 )
 134
 135 if test $ac_cv_c_byte_order = big ; then
 136         ac_cv_c_big_endian=1
 137         ac_cv_c_little_endian=0
 138 elif test $ac_cv_c_byte_order = little ; then
 139         ac_cv_c_big_endian=0
 140         ac_cv_c_little_endian=1
 141 else
 142         ac_cv_c_big_endian=0
 143         ac_cv_c_little_endian=0
 144
 145         AC_MSG_WARN([[*****************************************************************]])
 146         AC_MSG_WARN([[*** Not able to determine endian-ness of target processor.       ]])
 147         AC_MSG_WARN([[*** The constants CPU_IS_BIG_ENDIAN and CPU_IS_LITTLE_ENDIAN in  ]])
 148         AC_MSG_WARN([[*** src/config.h may need to be hand editied.                    ]])
 149         AC_MSG_WARN([[*****************************************************************]])
 150         fi
 151
 152 ]
 153 )# MN_C_FIND_ENDIAN
 154
 155