gdcmUnpacker12Bits.cxx

/*=========================================================================

  Program: GDCM (Grassroots DICOM). A DICOM library
  Module:  $URL$

  Copyright (c) 2006-2009 Mathieu Malaterre
  All rights reserved.
  See Copyright.txt or http://gdcm.sourceforge.net/Copyright.html for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#include "gdcmUnpacker12Bits.h"

namespace gdcm
{

00020 bool Unpacker12Bits::Unpack(char *out, const char *in, size_t n)
{
  if( n % 3 ) return false; // 3bytes are actually 2 words
  // http://groups.google.com/group/comp.lang.c/msg/572bc9b085c717f3
  short *q = (short*)out;
  const unsigned char *p = (unsigned char*)in;
  const unsigned char *end = p+n;
  unsigned char b0,b1,b2;

  while (p!=end)
    {
    b0 = *p++;
    b1 = *p++;
    b2 = *p++;
    *q++ = ((b1 & 0xf) << 8) + b0;
    *q++ = (b1>>4) + (b2<<4);
    } 
  return true;
}

00040 bool Unpacker12Bits::Pack(char *out, const char *in, size_t n)
{
  if( n % 4 ) return false; // we need an even number of 'words' so that 2 words are split in 3 bytes
  unsigned char *q = (unsigned char*)out;
  const unsigned short *p = (unsigned short*)in;
  const unsigned short *end = (unsigned short*)(in+n);
  unsigned short b0,b1;

  while(p!=end)
    {
    b0 = *p++;
    b1 = *p++;

    *q++ = (b0 & 0xff);
    *q++ = (b0 >> 8) + ((b1 & 0xf) << 4);
    *q++ = b1 >> 4;
    }
  return false;
}

} // end namespace gdcm