/*
 * (C) 2006-2014 see Authors.txt
 *
 * This file is part of MPC-BE.
 *
 * MPC-BE is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * MPC-BE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "stdafx.h"
#include "H264Nalu.h"

void CH264Nalu::SetBuffer(BYTE* pBuffer, size_t nSize, int nNALSize/* = 0*/)
{
	m_pBuffer		= pBuffer;
	m_nSize			= nSize;
	m_nNALSize		= nNALSize;
	m_nCurPos		= 0;
	m_nNextRTP		= 0;

	m_nNALStartPos	= 0;
	m_nNALDataPos	= 0;

	nal_unit_type	= NALU_TYPE_UNKNOWN;

	if (!nNALSize && nSize) {
		MoveToNextAnnexBStartcode();
	}
}

bool CH264Nalu::MoveToNextAnnexBStartcode()
{
	if (m_nSize < 4) {
		return false;
	}
	size_t nBuffEnd = m_nSize - 4;

	for (size_t i = m_nCurPos; i < nBuffEnd; i++) {
		if ((*((DWORD*)(m_pBuffer + i)) & 0x00FFFFFF) == 0x00010000) {
			// Find next AnnexB Nal
			m_nCurPos = i;
			return true;
		}
	}

	m_nCurPos = m_nSize;
	return false;
}

bool CH264Nalu::MoveToNextRTPStartcode()
{
	if (m_nNextRTP < m_nSize) {
		m_nCurPos = m_nNextRTP;
		return true;
	}

	m_nCurPos = m_nSize;
	return false;
}

bool CH264Nalu::ReadNext()
{
	if (m_nCurPos >= m_nSize) {
		return false;
	}

	if ((m_nNALSize != 0) && (m_nCurPos == m_nNextRTP)) {
		// RTP Nalu type : (XX XX) XX XX NAL..., with XX XX XX XX or XX XX equal to NAL size
		m_nNALStartPos	= m_nCurPos;
		m_nNALDataPos	= m_nCurPos + m_nNALSize;
		unsigned nTemp	= 0;
		for (int i = 0; i < m_nNALSize; i++) {
			nTemp = (nTemp << 8) + m_pBuffer[m_nCurPos++];
		}
		m_nNextRTP += nTemp + m_nNALSize;
		MoveToNextRTPStartcode();
	} else {
		// Remove trailing bits
		while (m_pBuffer[m_nCurPos] == 0x00 && ((*((DWORD*)(m_pBuffer + m_nCurPos)) & 0x00FFFFFF) != 0x00010000)) {
			m_nCurPos++;
		}

		// AnnexB Nalu : 00 00 01 NAL...
		m_nNALStartPos	= m_nCurPos;
		m_nCurPos	   += 3;
		m_nNALDataPos	= m_nCurPos;
		MoveToNextAnnexBStartcode();
	}

	forbidden_bit		= (m_pBuffer[m_nNALDataPos] >> 7) & 1;
	nal_reference_idc	= (m_pBuffer[m_nNALDataPos] >> 5) & 3;
	nal_unit_type		= (NALU_TYPE)(m_pBuffer[m_nNALDataPos] & 0x1f);

	return true;
}

bool CH265Nalu::ReadNext()
{
	if (__super::ReadNext()) {
		nal_unit_type = (NALU_TYPE)((m_pBuffer[m_nNALDataPos] >> 1) & 0x3F);
		return true;
	}

	return false;
}
