lttoolbox-unicode/lttoolbox/endian_util.h

   1 /*
   2  * Copyright (C) 2005 Universitat d'Alacant / Universidad de Alicante
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  17  * 02111-1307, USA.
  18  */
  19 #ifndef _ENDIANUTIL_
  20 #define _ENDIANUTIL_
  21
  22 #include <cctype>
  23 #include <cstdio>
  24 #include <iostream>
  25
  26 using namespace std;
  27
  28
  29 /**
  30  * Some definitions copied from somewhere in glibc
  31  */
  32 #ifndef __BYTE_ORDER
  33 #define __LITTLE_ENDIAN 1234
  34 #define __BIG_ENDIAN    4321
  35 #define __PDP_ENDIAN    3412
  36 #define __BYTE_ORDER __BIG_ENDIAN
  37 #endif
  38
  39
  40 /**
  41  * Generic class to process correctly endian-enabled I/O operations
  42  */
  43 template<class T>
  44 class EndianUtil
  45 {
  46 public:
  47   /**
  48    * Read procedure.
  49    * @param input the stream to read from.
  50    * @returns the first element readed from the current position of the stream
  51    */
  52   static T read(FILE *input)
  53   {
  54     T retval;
  55 #if __BYTE_ORDER == __BIG_ENDIAN
  56     fread(&retval, sizeof(T), 1, input);
  57 #else
  58     char *s = reinterpret_cast<char *>(&retval);
  59
  60     for(int i = sizeof(T)-1; i != -1; i--)
  61     {
  62       fread(&(s[i]), 1, 1, input);
  63     }
  64 #endif
  65     return retval;
  66   }
  67
  68   /**
  69    * Read procedure, C++ I/O version.
  70    * @param is the stream to read from.
  71    * @returns the first element readed from the current position of the stream
  72    */
  73   static T read(istream &is)
  74   {
  75     T retval;
  76 #if __BYTE_ORDER == __BIG_ENDIAN
  77     is.read((char *) &retval, sizeof(T));
  78 #else
  79     char *s = reinterpret_cast<char *>(&retval);
  80
  81     for(int i = sizeof(T)-1; i != -1; i--)
  82     {
  83       is.read(&(s[i]), sizeof(char));
  84     }
  85 #endif
  86     return retval;
  87   }
  88
  89   /**
  90    * Write procedure.
  91    * @param output the stream to write to
  92    * @param val the value of the generic object to write to the stream
  93    */
  94   static void write(FILE *output, T const &val)
  95   {
  96     T val2 = val;
  97 #if __BYTE_ORDER == __BIG_ENDIAN
  98     fwrite(&val2, sizeof(T), 1, output);
  99 #else
 100     char *s = reinterpret_cast<char *>(&val2);
 101
 102     for(int i = sizeof(T)-1; i != -1; i--)
 103     {
 104       fwrite(&(s[i]), 1, 1, output);
 105     }
 106 #endif
 107   }
 108
 109   /**
 110    * Write procedure, C++ I/O version.
 111    * @param output the stream to write to
 112    * @param val the value of the generic object to write to the stream
 113    */
 114   static void write(ostream &os, T const &val)
 115   {
 116     T val2 = val;
 117 #if __BYTE_ORDER == __BIG_ENDIAN
 118     os.write(reinterpret_cast<char *>(&val2), sizeof(T));
 119 #else
 120     char *s = reinterpret_cast<char *>(&val2);
 121
 122     for(int i = sizeof(T)-1; i != -1; i--)
 123     {
 124       os.write(&(s[i]), sizeof(char));
 125     }
 126 #endif
 127   }
 128 };
 129
 130 #endif