src/endian_check.cpp

   1 /* $Id: endian_check.cpp 23595 2011-12-19 17:48:04Z rubidium $ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   6  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   7  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   8  */
   9
  10 /**
  11  * @file endian_check.cpp
  12  * This pretty simple file checks if the system is LITTLE_ENDIAN or BIG_ENDIAN
  13  *  it does that by putting a 1 and a 0 in an array, and read it out as one
  14  *  number. If it is 1, it is LITTLE_ENDIAN, if it is 256, it is BIG_ENDIAN
  15  *
  16  * After that it outputs the contents of an include files (endian.h)
  17  *  that says or TTD_LITTLE_ENDIAN, or TTD_BIG_ENDIAN. Makefile takes
  18  *  care of the real writing to the file.
  19  */
  20
  21 #include <stdio.h>
  22 #include <string.h>
  23
  24 /** Supported endian types */
  25 enum Endian {
  26         ENDIAN_LITTLE, ///< little endian
  27         ENDIAN_BIG,    ///< big endian
  28 };
  29
  30 /**
  31  * Shortcut to printf("#define TTD_ENDIAN TTD_*_ENDIAN")
  32  * @param endian endian type to define
  33  */
  34 static inline void printf_endian(Endian endian)
  35 {
  36         printf("#define TTD_ENDIAN %s\n", endian == ENDIAN_LITTLE ? "TTD_LITTLE_ENDIAN" : "TTD_BIG_ENDIAN");
  37 }
  38
  39 /**
  40  * Main call of the endian_check program
  41  * @param argc argument count
  42  * @param argv arguments themselves
  43  * @return exit code
  44  */
  45 int main (int argc, char *argv[])
  46 {
  47         unsigned char endian_test[2] = { 1, 0 };
  48         int force_BE = 0, force_LE = 0, force_PREPROCESSOR = 0;
  49
  50         if (argc > 1 && strcmp(argv[1], "BE") == 0) force_BE = 1;
  51         if (argc > 1 && strcmp(argv[1], "LE") == 0) force_LE = 1;
  52         if (argc > 1 && strcmp(argv[1], "PREPROCESSOR") == 0) force_PREPROCESSOR = 1;
  53
  54         printf("#ifndef ENDIAN_H\n#define ENDIAN_H\n");
  55
  56         if (force_LE == 1) {
  57                 printf_endian(ENDIAN_LITTLE);
  58         } else if (force_BE == 1) {
  59                 printf_endian(ENDIAN_BIG);
  60         } else if (force_PREPROCESSOR == 1) {
  61                 /* Support for universal binaries on OSX
  62                  * Universal binaries supports both PPC and x86
  63                  * If a compiler for OSX gets this setting, it will always pick the correct endian and no test is needed
  64                  */
  65                 printf("#ifdef __BIG_ENDIAN__\n");
  66                 printf_endian(ENDIAN_BIG);
  67                 printf("#else\n");
  68                 printf_endian(ENDIAN_LITTLE);
  69                 printf("#endif\n");
  70         } else if (*(short*)endian_test == 1 ) {
  71                 printf_endian(ENDIAN_LITTLE);
  72         } else {
  73                 printf_endian(ENDIAN_BIG);
  74         }
  75         printf("#endif\n");
  76
  77         return 0;
  78 }