Emeric Vigier | eebea67 | 2012-08-06 17:36:30 -0400 | [diff] [blame] | 1 | dnl @synopsis AC_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([AC_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 | )# AC_C_FIND_ENDIAN |
| 154 | |
| 155 | |