/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/* $Id$ */

///////////////////////////////////////////////////////////////////////////////
/// 
/// This is a class for reading raw data memory buffers.
///
///////////////////////////////////////////////////////////////////////////////

#include "AliRawReaderMemory.h"
#include <TSystem.h>


ClassImp(AliRawReaderMemory)


AliRawReaderMemory::AliRawReaderMemory() :
  fBuffer(NULL),
  fBufferSize(0),
  fPosition(0),
  fEquipmentId(-1)
{
// create an object to read digits from
// the given memory location
}

AliRawReaderMemory::AliRawReaderMemory(UChar_t* memory, UInt_t size) :
  fBuffer(memory),
  fBufferSize(size),
  fPosition(0),
  fEquipmentId(-1)
{
// create an object to read digits from the given memory
}

AliRawReaderMemory::~AliRawReaderMemory()
{
// close the input memory
}

void AliRawReaderMemory::RequireHeader(Bool_t required)
{
  // Reading of raw data in case of missing
  // raw data header is not implemented for
  // this class
  if (!required)
    Fatal("AliRawReaderMemory","Reading of raw data without raw data header is not implemented !");

  AliRawReader::RequireHeader(required);
}

Bool_t AliRawReaderMemory::ReadHeader()
{
// read a data header at the current buffer position
// returns kFALSE if the mini header could not be read

  if (fEquipmentId == -1)
  {
    Warning("ReadHeader", "The equipment ID is not set for the DDL memory buffer.");
  }

  if (!fBuffer) return kFALSE;
  do {
    // Check if we would not read past the end of the buffer.
    if ( fPosition+fCount+sizeof(AliRawDataHeader) > fBufferSize ) return kFALSE;
    
    fHeader = reinterpret_cast<AliRawDataHeader*>(fBuffer+fPosition+fCount);
    
    // Check that the header is sane, that is the size does not go past the buffer.
    // Otherwise try again at the next word location.
    if (fHeader->fSize == 0 or fPosition+fCount+fHeader->fSize > fBufferSize) {
      if (fPosition + sizeof(UInt_t) <= fBufferSize) {
        fPosition += sizeof(UInt_t);
        continue;
      } else {
        Error("ReadHeader", "Could not find a valid DDL header!");
        return kFALSE;
      }
    } else {
      fPosition += fCount + sizeof(AliRawDataHeader);
    }

    if (fHeader->fSize != 0xFFFFFFFF) {
      fCount = fHeader->fSize - sizeof(AliRawDataHeader);
    } else {
      fCount = fBufferSize - fPosition - sizeof(AliRawDataHeader);
    }
  } while (!IsSelected());

  return kTRUE;
}

Bool_t AliRawReaderMemory::ReadNextData(UChar_t*& data)
{
// reads the next payload at the current buffer position
// returns kFALSE if the data could not be read

  while (fCount == 0) {
    if (!ReadHeader()) return kFALSE;
  }
  UInt_t currentPosition = fPosition;
  fPosition += fCount;
  fCount = 0;

  data = fBuffer+currentPosition;
  return kTRUE;
}

Bool_t AliRawReaderMemory::ReadNext(UChar_t* data, Int_t size)
{
// reads the next block of data at the current buffer position
// returns kFALSE if the data could not be read

  if ( fBufferSize-fPosition < (UInt_t)size ) return kFALSE;

  memcpy( data, fBuffer+fPosition, size );
  fCount -= size;
  fPosition += size;
  return kTRUE;
}


Bool_t AliRawReaderMemory::Reset()
{
// reset the current position in the buffer to the beginning of the curevent

  fHeader = NULL;
  fCount = 0;
  fPosition = 0;
  return kTRUE;
}

Bool_t AliRawReaderMemory::NextEvent()
{
// each memory buffer always contains only one event
  if (fEventNumber < 0) {
    fEventNumber++;
    return kTRUE;
  }
  else
    return kFALSE; 
}

Bool_t AliRawReaderMemory::RewindEvents()
{
// reset the event counter
  fEventNumber = -1;

  return Reset();
}

Bool_t AliRawReaderMemory::SetMemory( UChar_t* memory, ULong_t size )
{
  fBuffer = memory;
  fBufferSize = size;
  fHeader = NULL;
  fCount = 0;
  fPosition = 0;
  return (fBuffer && fBufferSize>0) ? kTRUE : kFALSE;
}