//===========================================================================
//  Copyright (C) 1999 Matt Timmermans
//  Free for non-commercial purposes as long as this notice remains intact.
//  To discuss commercial use, mail me at matt@timmermans.org
//
//  trivial.cpp
//
//  These classes implement a simple bijection between byte streams and
//  "finitely odd" bit streams, where a finitely odd bit stream is of infinite
//  length, but the position of the rightmost 1 bit is finite, i.e., there
//  is a final 1 bit somewhere in the stream, which is followed by an infinite
//  number of zero bits
//
//===========================================================================

#include "trivial.h"

bool TrivialFOEncoder::FillQ(IOByteQ *dest)
  {
  unsigned outlen=0;
  unsigned blocktail=m_blocklen-1;
  unsigned i;
  BYTE c;

  while((outlen<256)&&(!m_done))
    {
    outlen+=m_blocklen;
    //do a block or end
    if (m_in.AtEnd()) //ending
      {
      if (m_reserved0)
        *(dest->Put(1))=(BYTE)128;
      m_done=true;
      break;
      }
    //output a block
    c=m_in.Get();
    *(dest->Put(1))=c;
    if (m_reserved0)
      m_reserved0=!(c&127);
    else
      m_reserved0=!c;

    for(i=blocktail;i;--i)
      {
      c=(m_in.AtEnd()?0:m_in.Get());
      *(dest->Put(1))=c;
      if (c)
        m_reserved0=false;
      }
    }
  return !m_done;
  }


bool TrivialFODecoder::FillQ(IOByteQ *dest)
  {
  unsigned outlen=0;
  unsigned blocktail=m_blocklen-1;
  unsigned i;
  BYTE c;

  while((outlen<256)&&(!m_done))
    {
    outlen+=m_blocklen;
    //do a block or end
    c=m_in.Get();

    if (m_reserved0)
      {
      if ((c==(BYTE)128)&&m_in.InTail())
        {
        m_done=true;
        break;
        }
      *(dest->Put(1))=c;
      m_reserved0=!(c&127);
      }
    else
      {
      if ((c==0)&&m_in.InTail())
        {
        m_done=true;
        break;
        }
      *(dest->Put(1))=c;
      m_reserved0=!c;
      }

    for(i=blocktail;i;--i)
      {
      c=m_in.Get();
      *(dest->Put(1))=c;
      if (c)
        m_reserved0=false;
      }
    }
  return !m_done;
  }