endian problem

I am reading my input file one byte at a time and writing each character to my output file, like so:

while(!fIn2.eof()) {
while (fIn2.get(xCh)){
fout.put(xCh);
}

The problem resides in the fact that now, i need to write it a little bit differently. If I had bits in this order, for example:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

I would need them written like this:

2 1 4 3 6 5 8 7 10 9 12 11 14 13 16 15
----------------------------------------------------------------

any ideas on how to read in data and write it like this?

Thanks,
keith

You would have to use arrays to flip-flop every two numbers, like:

while (eof)
{
-read next two numbers
-switch them in the array
}
- write to output file

alrighty. say i have to read a lot of bytes (and i do) and switch every two around....what kind of code am i looking at? any short example-code would help a ton.

thanks,
keith

Here's one way.

Code:

---

  while(!fIn2.eof()) {
      while (fIn2.get(xCh)){
        if (fIn2.get(yCh))
            fout.put(yCh);
        fout.put(xCh);
      }
  }

---

Code:

---

//assuming you read 256 bytes into buf

unsigned short *shortbuf = (unsigned short*)buf;
for(int i=0; i < 128; i++, shortbuf++)
  *shortbuf = (*shortbuf >> 8) | (*shortbuf << 8);

---

Wait, are you flipping BYTES or BITS around? Your first post seems to say you're flipping bits within each byte.

In that case:

Code:

---

unsigned char flipBits(unsigned char c){
  return ( ((c & 0x55) << 1) & ((c & 0xAA) >> 1) );
}

---

Hmm, you're right Cat, he does say bits.