Convert a file from Little endian to Big endian

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Hi,

I need to convert a file from Little Endian to Big Endian under Linux 32 bit. I know that I can do the program myself, but I was wondering if there is any program already done that can do the job.

Thanks in advance

Posted 13-Aug-13 1:14am

GiZmoDragonBack

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Comments

ridoy 13-Aug-13 7:26am

good decision!

ridoy 13-Aug-13 7:29am

Check it http://www.linuxquestions.org/questions/programming-9/converting-a-binary-file-from-little-endian-to-big-endian-899742/

2 solutions

Solution 1

Endianness refers to BYTE ordering within data types, hence your question is vague.
If it's some sort of binary file, you need to read every structure in and reverse the BYTES in it, then serialize back to disk. If it's some sort of multibyte text file you need to lookup the encoding and act accordingly.

sidenote: If you want to swap pairs of bytes in a file use dd with
conv=swab

LE: try this for just reversing everything:

C++

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char** argv)
{
  FILE* input = NULL;
  FILE* output = NULL;
  unsigned long size = 0;
  unsigned long itr = 0;
  unsigned char* buffer;


  if(argc != 3)
    return 0;
  input = fopen(argv[1],"rb");
  output = fopen(argv[2],"wb");
  
  if(!input || !output)
    fprintf(stderr,"could not open file");
  fseek(input,0,SEEK_END);
  size = ftell(input);
  fseek(input,0,SEEK_SET);

  buffer = (unsigned char*)malloc(size);
  
  fread(buffer,1,size,input);
  fclose(input);
  for(itr = size;itr>0;itr--)
  {
    fwrite(&buffer[itr-1],1,1,output);
  }
  fclose(output);
return 0;
}

compile and use like this:

./application inputfile outputfile

Posted 13-Aug-13 1:38am

slack7219

Updated 13-Aug-13 2:18am

v3

Comments

GiZmoDragonBack 13-Aug-13 7:47am

Thanks. I know the essence behind the endianess. I just want to swap all the bytes inside the file. My program is expecting a Big endian file, but I produce a little endian file. The dd is quite close, but it swap in pairs

GiZmoDragonBack 13-Aug-13 10:13am

Close enough. I edited your code in the shape the I actually need it. Thanks

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

GiZmoDragonBack · Accepted Answer · 2013-08-13T04:14:00

@slack7219723

This is the solution that I was looking for. I modify slightly your code to obtain this

C#

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char** argv)
{
    FILE* input = NULL;
    FILE* output = NULL;
    unsigned long size = 0;
    unsigned long itr = 0;
    unsigned char* buffer;

    if(argc != 3)
    return 0;
    input = fopen(argv[1],"rb");
    output = fopen(argv[2],"wb");

    if(!input || !output)
        fprintf(stderr,"could not open file");
    fseek(input,0,SEEK_END);
    size = ftell(input);
    fseek(input,0,SEEK_SET);

    buffer = (unsigned char*)malloc(size);

    fread(buffer,1,size,input);
    fclose(input);
    for(itr = 0;itr<size;itr=itr+4)
    {
        fwrite(&buffer[itr + 3],1,1,output);
        fwrite(&buffer[itr + 2],1,1,output);
        fwrite(&buffer[itr + 1],1,1,output);
        fwrite(&buffer[itr + 0],1,1,output);
    }
    fclose(output);
    return 0;
}

Convert a file from Little endian to Big endian

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Convert a file from Little endian to Big endian

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