Merge pull request #91 from thbeu/fix-endianness

Detect byte order at compile time

CMakeLists.txt

@@ -116,6 +116,12 @@ target_include_directories(${PACKAGE}
     $<INSTALL_INTERFACE:include>
 )
 
+include(TestBigEndian)
+if(HAVE_BYTE_ORDER_BIG_ENDIAN)
+  # Define SHP_BIG_ENDIAN if the system is big-endian
+  add_definitions(-DSHP_BIG_ENDIAN=1)
+endif()
+
 if(MSVC)
   target_compile_options(${PACKAGE} PRIVATE /W4)
 else()
@@ -292,4 +298,4 @@ endif()
 
 include(cmake/contrib.cmake)
 
-add_subdirectory (cmake)
+add_subdirectory(cmake)

configure.ac

@@ -9,6 +9,12 @@ AC_INIT(shapelib, shapelib_version_major.shapelib_version_minor.shapelib_version
 AC_CONFIG_MACRO_DIR(m4)
 AC_CONFIG_SRCDIR(shapefil.h)
 
+AC_C_BIGENDIAN
+if test "x$ac_cv_c_bigendian" = "xyes"; then
+  # Define SHP_BIG_ENDIAN if the system is big-endian
+  AC_DEFINE([SHP_BIG_ENDIAN], [1], [Define if the system is big-endian])
+fi
+
 AM_INIT_AUTOMAKE([foreign -Wall -Wextra])
 
 AM_SILENT_RULES([yes])

sbnsearch.c

@@ -136,18 +136,6 @@ static void SwapWord(int length, void *wordP)
 SBNSearchHandle SBNOpenDiskTree(const char *pszSBNFilename,
                                 const SAHooks *psHooks)
 {
-    /* -------------------------------------------------------------------- */
-    /*  Establish the byte order on this machine.                           */
-    /* -------------------------------------------------------------------- */
-    bool _bBigEndian;
-    {
-        int i = 1;
-        if (*REINTERPRET_CAST(unsigned char *, &i) == 1)
-            _bBigEndian = false;
-        else
-            _bBigEndian = true;
-    }
-
     /* -------------------------------------------------------------------- */
     /*      Initialize the handle structure.                                */
     /* -------------------------------------------------------------------- */
@@ -191,13 +179,12 @@ SBNSearchHandle SBNOpenDiskTree(const char *pszSBNFilename,
     memcpy(&hSBN->dfMaxX, abyHeader + 48, 8);
     memcpy(&hSBN->dfMaxY, abyHeader + 56, 8);
 
-    if (!_bBigEndian)
-    {
-        SwapWord(8, &hSBN->dfMinX);
-        SwapWord(8, &hSBN->dfMinY);
-        SwapWord(8, &hSBN->dfMaxX);
-        SwapWord(8, &hSBN->dfMaxY);
-    }
+#if !defined(SHP_BIG_ENDIAN)
+    SwapWord(8, &hSBN->dfMinX);
+    SwapWord(8, &hSBN->dfMinY);
+    SwapWord(8, &hSBN->dfMaxX);
+    SwapWord(8, &hSBN->dfMaxY);
+#endif
 
     if (hSBN->dfMinX > hSBN->dfMaxX || hSBN->dfMinY > hSBN->dfMaxY)
     {

shapefil.h

@@ -22,6 +22,29 @@
 #include "cpl_conv.h"
 #endif
 
+#if !defined(SHP_BIG_ENDIAN)
+#if defined(CPL_MSB)
+#define SHP_BIG_ENDIAN 1
+#elif (defined(__GNUC__) && __GNUC__ >= 5) ||                                  \
+    (defined(__GNUC__) && defined(__GNUC_MINOR__) && __GNUC__ == 4 &&          \
+     __GNUC_MINOR__ >= 6)
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define SHP_BIG_ENDIAN 1
+#endif
+#elif defined(__GLIBC__)
+#if __BYTE_ORDER == __BIG_ENDIAN
+#define SHP_BIG_ENDIAN 1
+#endif
+#elif defined(_BIG_ENDIAN) && !defined(_LITTLE_ENDIAN)
+#define SHP_BIG_ENDIAN 1
+#elif defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN)
+#elif defined(__sparc) || defined(__sparc__) || defined(_POWER) ||             \
+    defined(__powerpc__) || defined(__ppc__) || defined(__hpux) ||             \
+    defined(_MIPSEB) || defined(_POWER) || defined(__s390__)
+#define SHP_BIG_ENDIAN 1
+#endif
+#endif
+
 #ifdef __cplusplus
 extern "C"
 {