[Caml-list] [PATCH 2/2] configure: Check endianess by using the preprocessor

[Stefan Hellermann <stefan@the2masters.de>]

Signed-off-by: Stefan Hellermann <stefan@the2masters.de>
---
 config/auto-aux/endian.c | 60 +++++++++++++++++++-----------------------------
 configure                | 26 ++++++++++++---------
 2 files changed, 38 insertions(+), 48 deletions(-)

diff --git a/config/auto-aux/endian.c b/config/auto-aux/endian.c
index 5dc623a..eee48c8 100644
--- a/config/auto-aux/endian.c
+++ b/config/auto-aux/endian.c
@@ -1,40 +1,26 @@
-/***********************************************************************/
-/*                                                                     */
-/*                                OCaml                                */
-/*                                                                     */
-/*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         */
-/*                                                                     */
-/*  Copyright 1996 Institut National de Recherche en Informatique et   */
-/*  en Automatique.  All rights reserved.  This file is distributed    */
-/*  under the terms of the GNU Library General Public License, with    */
-/*  the special exception on linking described in file ../../LICENSE.  */
-/*                                                                     */
-/***********************************************************************/
-
-#include <string.h>
-#include "m.h"
+// Try to find the right includes
+#if defined(__linux__) || defined(__CYGWIN__)
+#  define _BSD_SOURCE
+#  include <endian.h>
+#elif defined(__APPLE__)
+#  include <libkern/OSByteOrder.h>
+#elif defined(BSD)
+#   include <sys/endian.h>
+#elif defined(_WIN16) || defined(_WIN32) || defined(_WIN64)
+#  include <winsock2.h>
+#  include <sys/param.h>
+#endif
 
-#ifndef ARCH_SIXTYFOUR
-long intval = 0x41424344L;
-char * bigendian = "ABCD";
-char * littleendian = "DCBA";
+#if defined(__BIG_ENDIAN__) || \
+  defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ || \
+  defined(__BYTE_ORDER) && __BYTE_ORDER == __BIG_ENDIAN || \
+  defined(BYTE_ORDER) && BYTE_ORDER == BIG_ENDIAN
+0
+#elif defined(__LITTLE_ENDIAN__) || \
+  defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ || \
+  defined(__BYTE_ORDER) && __BYTE_ORDER == __LITTLE_ENDIAN || \
+  defined(BYTE_ORDER) && BYTE_ORDER == LITTLE_ENDIAN
+1
 #else
-long intval = 0x4142434445464748L;
-char * bigendian = "ABCDEFGH";
-char * littleendian = "HGFEDCBA";
+#  error Cannot detect endianess of target
 #endif
-
-int main(void)
-{
-  long n[2];
-  char * p;
-
-  n[0] = intval;
-  n[1] = 0;
-  p = (char *) n;
-  if (strcmp(p, bigendian) == 0)
-    return 0;
-  if (strcmp(p, littleendian) == 0)
-    return 1;
-  return 2;
-}
diff --git a/configure b/configure
index e3ea7eb..b7c3348 100755
--- a/configure
+++ b/configure
@@ -552,22 +552,26 @@ echo "#define SIZEOF_LONGLONG $5" >> m.h
 
 # Determine endianness
 
-sh ./runtest endian.c
-case $? in
-  0) inf "This is a big-endian architecture."
-     echo "#define ARCH_BIG_ENDIAN" >> m.h;;
-  1) inf "This is a little-endian architecture."
-     echo "#undef ARCH_BIG_ENDIAN" >> m.h;;
-  2) err "This architecture seems to be neither big endian nor little" \
-         "endian.\n OCaml won't run on this architecture.";;
-  *) case $target in
+ret=`sh ./preprocesstest endian.c`
+if test "$?" -eq 0; then
+  set $ret
+  case "$1" in
+    0) inf "This is a big-endian architecture."
+       echo "#define ARCH_BIG_ENDIAN" >> m.h;;
+    1) inf "This is a little-endian architecture."
+       echo "#undef ARCH_BIG_ENDIAN" >> m.h;;
+    *) err "This architecture seems to be neither big endian nor little" \
+           "endian.\n OCaml won't run on this architecture.";;
+  esac
+else
+  case $target in
        *-*-mingw*) inf "This is a little-endian architecture."
                    echo "#undef ARCH_BIG_ENDIAN" >> m.h;;
        *) wrn "Something went wrong during endianness determination.\n" \
               "You will have to figure out endianness yourself\n" \
               "(option ARCH_BIG_ENDIAN in m.h).";;
-     esac;;
-esac
+     esac
+fi
 
 # Determine alignment constraints
 
-- 
2.1.4