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|
/*****************************************************************
|
| AP4 - Bitstream Utility
|
| Copyright 2002-2008 Axiomatic Systems, LLC
|
|
| This file is part of Bento4/AP4 (MP4 Atom Processing Library).
|
| Unless you have obtained Bento4 under a difference license,
| this version of Bento4 is Bento4|GPL.
| Bento4|GPL 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 2, or (at your option)
| any later version.
|
| Bento4|GPL 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 Bento4|GPL; see the file COPYING. If not, write to the
| Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
| 02111-1307, USA.
|
****************************************************************/
/*----------------------------------------------------------------------
| For efficiency reasons, this bitstream library only handles
| data buffers that are a power of 2 in size
+---------------------------------------------------------------------*/
/*----------------------------------------------------------------------
| includes
+---------------------------------------------------------------------*/
#include "Ap4BitStream.h"
#include "Ap4Utils.h"
/*----------------------------------------------------------------------
| AP4_BitStream::AP4_BitStream
+---------------------------------------------------------------------*/
AP4_BitStream::AP4_BitStream()
{
m_Buffer = new AP4_UI08[AP4_BITSTREAM_BUFFER_SIZE];
Reset();
}
/*----------------------------------------------------------------------
| AP4_BitStream::~AP4_BitStream
+---------------------------------------------------------------------*/
AP4_BitStream::~AP4_BitStream()
{
delete[] m_Buffer;
}
/*----------------------------------------------------------------------
| AP4_BitStream::Reset
+---------------------------------------------------------------------*/
AP4_Result
AP4_BitStream::Reset()
{
m_In = 0;
m_Out = 0;
m_BitsCached = 0;
m_Cache = 0;
m_Flags = 0;
return AP4_SUCCESS;
}
/*----------------------------------------------------------------------
| AP4_BitStream::ByteAlign
+---------------------------------------------------------------------*/
AP4_Result
AP4_BitStream::ByteAlign()
{
unsigned int to_flush = m_BitsCached & 7;
if (to_flush > 0) SkipBits(to_flush);
return AP4_SUCCESS;
}
/*----------------------------------------------------------------------
| AP4_BitStream::GetContiguousBytesFree
+---------------------------------------------------------------------*/
AP4_Size
AP4_BitStream::GetContiguousBytesFree()
{
return
(m_In < m_Out) ?
(m_Out - m_In - 1) :
(m_Out == 0 ? (AP4_BITSTREAM_BUFFER_SIZE - m_In - 1) :
(AP4_BITSTREAM_BUFFER_SIZE - m_In));
}
/*----------------------------------------------------------------------
| AP4_BitStream_GetBytesFree
+---------------------------------------------------------------------*/
AP4_Size
AP4_BitStream::GetBytesFree()
{
return
(m_In < m_Out) ?
(m_Out - m_In - 1) :
(AP4_BITSTREAM_BUFFER_SIZE + (m_Out - m_In) - 1);
}
/*----------------------------------------------------------------------+
| AP4_BitStream::WriteBytes
+----------------------------------------------------------------------*/
AP4_Result
AP4_BitStream::WriteBytes(const AP4_UI08* bytes,
AP4_Size byte_count)
{
/* check parameters */
if (byte_count == 0) return AP4_SUCCESS;
if (bytes == NULL) return AP4_ERROR_INVALID_PARAMETERS;
/* check that we have enough space */
if (GetBytesFree() < byte_count) {
return AP4_FAILURE;
}
/* write the bytes */
if (m_In < m_Out) {
AP4_CopyMemory(m_Buffer+m_In, bytes, byte_count);
AP4_BITSTREAM_POINTER_ADD(m_In, byte_count);
} else {
unsigned int chunk = AP4_BITSTREAM_BUFFER_SIZE - m_In;
if (chunk > byte_count) chunk = byte_count;
AP4_CopyMemory(m_Buffer+m_In, bytes, chunk);
AP4_BITSTREAM_POINTER_ADD(m_In, chunk);
if (chunk != byte_count) {
AP4_CopyMemory(m_Buffer+m_In,
bytes+chunk, byte_count-chunk);
AP4_BITSTREAM_POINTER_ADD(m_In, byte_count-chunk);
}
}
return AP4_SUCCESS;
}
/*----------------------------------------------------------------------
| AP4_BitStream_GetContiguousBytesAvailable
+---------------------------------------------------------------------*/
AP4_Size
AP4_BitStream::GetContiguousBytesAvailable()
{
return
(m_Out <= m_In) ?
(m_In - m_Out) :
(AP4_BITSTREAM_BUFFER_SIZE - m_Out);
}
/*----------------------------------------------------------------------
| AP4_BitStream::GetBytesAvailable
+---------------------------------------------------------------------*/
AP4_Size
AP4_BitStream::GetBytesAvailable()
{
return
(m_Out <= m_In) ?
(m_In - m_Out) :
(m_In + (AP4_BITSTREAM_BUFFER_SIZE - m_Out));
}
/*----------------------------------------------------------------------+
| AP4_BitStream::ReadBytes
+----------------------------------------------------------------------*/
AP4_Result
AP4_BitStream::ReadBytes(AP4_UI08* bytes,
AP4_Size byte_count)
{
if (byte_count == 0 || bytes == NULL) {
return AP4_ERROR_INVALID_PARAMETERS;
}
/* Gets bytes from the cache */
ByteAlign();
while (m_BitsCached > 0 && byte_count > 0) {
*bytes = (AP4_UI08)ReadBits(8);
++ bytes;
-- byte_count;
}
/* Get other bytes */
if (byte_count > 0) {
if (m_Out < m_In) {
AP4_CopyMemory(bytes, m_Buffer + m_Out, byte_count);
AP4_BITSTREAM_POINTER_ADD(m_Out, byte_count);
} else {
unsigned int chunk = AP4_BITSTREAM_BUFFER_SIZE - m_Out;
if (chunk >= byte_count) chunk = byte_count;
AP4_CopyMemory(bytes, m_Buffer+m_Out, chunk);
AP4_BITSTREAM_POINTER_ADD(m_Out, chunk);
if (chunk != byte_count) {
AP4_CopyMemory(bytes+chunk,
m_Buffer+m_Out,
byte_count-chunk);
AP4_BITSTREAM_POINTER_ADD(m_Out, byte_count-chunk);
}
}
}
return AP4_SUCCESS;
}
/*----------------------------------------------------------------------+
| AP4_BitStream::PeekBytes
+----------------------------------------------------------------------*/
AP4_Result
AP4_BitStream::PeekBytes(AP4_UI08* bytes,
AP4_Size byte_count)
{
int bits_cached_byte;
if (byte_count == 0 || bytes == NULL) {
return AP4_ERROR_INVALID_PARAMETERS;
}
/* Gets bytes from the cache */
bits_cached_byte = m_BitsCached & ~7;
while (bits_cached_byte > 0 && byte_count > 0) {
*bytes = (m_Cache >> bits_cached_byte) & 0xFF;
++ bytes;
-- byte_count;
bits_cached_byte -= 8;
}
/* Get other bytes */
if (byte_count > 0) {
if (m_In > m_Out) {
AP4_CopyMemory(bytes, m_Buffer + m_Out, byte_count);
} else {
unsigned int out = m_Out;
unsigned int chunk = AP4_BITSTREAM_BUFFER_SIZE - out;
if (chunk >= byte_count) {
chunk = byte_count;
}
AP4_CopyMemory(bytes, m_Buffer+out, chunk);
AP4_BITSTREAM_POINTER_ADD(out, chunk);
if (chunk != byte_count) {
AP4_CopyMemory(bytes+chunk,
m_Buffer+out,
byte_count-chunk);
}
}
}
return AP4_SUCCESS;
}
/*----------------------------------------------------------------------+
| AP4_BitStream::SkipBytes
+----------------------------------------------------------------------*/
AP4_Result
AP4_BitStream::SkipBytes(AP4_Size byte_count)
{
AP4_BITSTREAM_POINTER_ADD(m_Out, byte_count);
return AP4_SUCCESS;
}
|
