fread_be.cpp

/*
    Copyright 2017 Philippe Grandclement
 
    This file is part of Kadath.
 
    Kadath 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, either version 3 of the License, or
    (at your option) any later version.
 
    Kadath 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.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with Kadath.  If not, see <http://www.gnu.org/licenses/>.
*/
 
// C headers
#include <stdio.h>
#include <assert.h>
namespace Kadath {
            //-------------------------//
            //  int version        //
            //-------------------------//
            
int fread_be(int* aa, int size, int nb, FILE* fich) {
 
    assert(size == 4) ;
    
    // Determines whether the default storage is big endian
    //  or large endians
    
    int itest = 1 ;
    bool little_endian = ( *( reinterpret_cast<char*>(&itest) ) == 1) ;
    
    if (little_endian) {
 
        int size_tot = 4 * nb ;
 
        char* bytes_big = new char[size_tot] ;
        
        int nr = static_cast<int>(fread(bytes_big, 1, size_tot, fich)) ;
        
        char* pbig =  bytes_big ;
        char* plit = reinterpret_cast<char*>( aa ) ;
        
        for (int j=0; j< nb; j++) {
        
            for (int i=0; i<4; i++) {
                plit[i] = pbig[3-i] ;
            }
        
            plit += 4 ;     // next item
            pbig += 4 ;
            
        }
        
        delete [] bytes_big ; 
 
        return nr / 4 ;     
 
    }
    else {  // Big endian case: nothing to do:
    
        return static_cast<int>(fread(aa, size, nb, fich)) ;
    }
        
}
 
            //-------------------------//
            //  double version     //
            //-------------------------//
            
int fread_be(double* aa, int size, int nb, FILE* fich) {
 
    assert(size == 8) ;
    
    // Determines whether the default storage is big endian
    //  or large endians
    
    int itest = 1 ;
    bool little_endian = ( *( reinterpret_cast<char*>(&itest) ) == 1) ;
    
    if (little_endian) {
 
        int size_tot = 8 * nb ;
 
        char* bytes_big = new char[size_tot] ;
 
        int nr = static_cast<int>(fread(bytes_big, 1, size_tot, fich)) ;
        
        char* pbig =  bytes_big ;
        char* plit = reinterpret_cast<char*>( aa ) ;
        
        for (int j=0; j< nb; j++) {
        
            for (int i=0; i<8; i++) {
                plit[i] = pbig[7-i] ;
            }
        
            plit += 8 ;     // next item
            pbig += 8 ;
            
        }
 
        delete [] bytes_big ;
 
        return nr / 8 ;     
        
    }
    else {  // Big endian case: nothing to do:
    
        return static_cast<int>(fread(aa, size, nb, fich)) ;
    }
        
}
}