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/* ------------------------------------------------------------------
* Copyright (C) 1998-2009 PacketVideo
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied.
* See the License for the specific language governing permissions
* and limitations under the License.
* -------------------------------------------------------------------
*/
/*
Pathname: getbits.h
------------------------------------------------------------------------------
REVISION HISTORY
Description: Update comments for the structure
Description: Move structur to another file
Who: Date: MM/DD/YYYY
Description:
------------------------------------------------------------------------------
INCLUDE DESCRIPTION
Header file for the function getbits().
------------------------------------------------------------------------------
*/
/*----------------------------------------------------------------------------
; CONTINUE ONLY IF NOT ALREADY DEFINED
----------------------------------------------------------------------------*/
#ifndef GETBITS_H
#define GETBITS_H
#ifdef __cplusplus
extern "C"
{
#endif
/*----------------------------------------------------------------------------
; INCLUDES
----------------------------------------------------------------------------*/
#include "pv_audio_type_defs.h"
#include "ibstream.h"
/*----------------------------------------------------------------------------
; MACROS
; Define module specific macros here
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; DEFINES
; Include all pre-processor statements here.
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; EXTERNAL VARIABLES REFERENCES
; Declare variables used in this module but defined elsewhere
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; SIMPLE TYPEDEF'S
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; ENUMERATED TYPEDEF'S
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; STRUCTURES TYPEDEF'S
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; GLOBAL FUNCTION DEFINITIONS
; Function Prototype declaration
----------------------------------------------------------------------------*/
#define INBUF_ARRAY_INDEX_SHIFT (3)
#define INBUF_BIT_WIDTH (1<<(INBUF_ARRAY_INDEX_SHIFT))
#define INBUF_BIT_MODULO_MASK ((INBUF_BIT_WIDTH)-1)
#define MAX_GETBITS (25)
#define CHECK_INPUT_BUFFER_LIMITS 1
__inline UInt32 getbits(
const UInt neededBits,
BITS *pInputStream)
{
UInt32 returnValue = 0;
UInt offset;
UInt bitIndex;
UChar *pElem; /* Needs to be same type as pInput->pBuffer */
offset = (pInputStream->usedBits) >> INBUF_ARRAY_INDEX_SHIFT;
pElem = pInputStream->pBuffer + offset;
#if CHECK_INPUT_BUFFER_LIMITS
offset = pInputStream->inputBufferCurrentLength - offset;
/* check if access to input buffer does not go beyond boundaries */
if (offset > 3)
{
returnValue = (((UInt32) * (pElem)) << 24) |
(((UInt32) * (pElem + 1)) << 16) |
(((UInt32) * (pElem + 2)) << 8) |
((UInt32) * (pElem + 3));
}
else /* then access only available bytes */
{
/* Access to the bitstream beyond frame boundaries are not allowed,
* Here, only what was available before the end of the frame will
* be processed. Non-accessible bytes will be filled in with zeros.
* Zero values guarantees that the data structures are filled in with values
* that eventually will signal an error (like invalid parameters) or that allow
* completion of the parsing routine.
* Overrun is detected on file pvmp4audiodecodeframe.cpp.
*/
switch (offset)
{
case 3:
returnValue = (((UInt32) * (pElem + 2)) << 8);
case 2:
returnValue |= (((UInt32) * (pElem + 1)) << 16);
case 1:
returnValue |= (((UInt32) * (pElem)) << 24);
default:
break;
}
}
#else
returnValue = (((UInt32) * (pElem)) << 24) |
(((UInt32) * (pElem + 1)) << 16) |
(((UInt32) * (pElem + 2)) << 8) |
((UInt32) * (pElem + 3));
#endif
/* Remove extra high bits by shifting up */
bitIndex = (UInt)((pInputStream->usedBits) & INBUF_BIT_MODULO_MASK);
/* This line is faster way to mask off the high bits. */
returnValue = returnValue << (bitIndex);
/* Move the field down. */
returnValue = returnValue >> (32 - neededBits);
pInputStream->usedBits += neededBits;
return (returnValue);
}
__inline UInt get1bits(
BITS *pInputStream)
{
UInt returnValue;
UInt offset;
UInt bitIndex;
UChar *pElem; /* Needs to be same type as pInput->pBuffer */
offset = (pInputStream->usedBits) >> INBUF_ARRAY_INDEX_SHIFT;
pElem = pInputStream->pBuffer + offset;
#if CHECK_INPUT_BUFFER_LIMITS
returnValue = (offset < pInputStream->inputBufferCurrentLength) ? ((UInt) * (pElem)) : 0;
#else
returnValue = ((UInt32) * (pElem));
#endif
/* Remove extra high bits by shifting up */
bitIndex = (UInt)((pInputStream->usedBits++) & INBUF_BIT_MODULO_MASK);
/* This line is faster way to mask off the high bits. */
returnValue = 0xFF & (returnValue << (bitIndex));
/* Move the field down. */
return ((UInt)(returnValue >> 7));
}
__inline UInt get9_n_lessbits(
const UInt neededBits,
BITS *pInputStream)
{
UInt returnValue;
UInt offset;
UInt bitIndex;
UChar *pElem; /* Needs to be same type as pInput->pBuffer */
offset = (pInputStream->usedBits) >> INBUF_ARRAY_INDEX_SHIFT;
pElem = pInputStream->pBuffer + offset;
#if CHECK_INPUT_BUFFER_LIMITS
offset = pInputStream->inputBufferCurrentLength - offset;
/* check if access to input buffer does not go beyond boundaries */
if (offset > 1)
{
returnValue = (((UInt32) * (pElem)) << 8) |
((UInt32) * (pElem + 1));
}
else /* then access only available bytes */
{
/* Access to the bitstream beyond frame boundaries are not allowed,
* Here, only what was available before the end of the frame will
* be processed. Non-accessible bytes will be filled in with zeros.
* Zero values guarantees that the data structures are filled in with values
* that eventually will signal an error (like invalid parameters) or that allow
* completion of the parsing routine.
* Overrun is detected on file pvmp4audiodecodeframe.cpp
*/
switch (offset)
{
case 1:
returnValue = (((UInt32) * (pElem)) << 8);
break;
default:
returnValue = 0;
break;
}
}
#else
returnValue = (((UInt32) * (pElem)) << 8) |
((UInt32) * (pElem + 1)) ;
#endif
/* Remove extra high bits by shifting up */
bitIndex = (UInt)((pInputStream->usedBits) & INBUF_BIT_MODULO_MASK);
pInputStream->usedBits += neededBits;
/* This line is faster way to mask off the high bits. */
returnValue = 0xFFFF & (returnValue << (bitIndex));
/* Move the field down. */
return (UInt)(returnValue >> (16 - neededBits));
}
__inline UInt32 get17_n_lessbits(
const UInt neededBits,
BITS *pInputStream)
{
UInt32 returnValue;
UInt offset;
UInt bitIndex;
UChar *pElem; /* Needs to be same type as pInput->pBuffer */
offset = (pInputStream->usedBits) >> INBUF_ARRAY_INDEX_SHIFT;
pElem = pInputStream->pBuffer + offset;
#if CHECK_INPUT_BUFFER_LIMITS
offset = pInputStream->inputBufferCurrentLength - offset;
/* check if access to input buffer does not go beyond boundaries */
if (offset > 2)
{
returnValue = (((UInt32) * (pElem)) << 16) |
(((UInt32) * (pElem + 1)) << 8) |
((UInt32) * (pElem + 2));
}
else /* then access only available bytes */
{
/* Access to the bitstream beyond frame boundaries are not allowed,
* Here, only what was available before the end of the frame will
* be processed. Non-accessible bytes will be filled in with zeros.
* Zero values guarantees that the data structures are filled in with values
* that eventually will signal an error (like invalid parameters) or that allow
* completion of the parsing routine.
* Overrun is detected on file pvmp4audiodecodeframe.cpp
*/
returnValue = 0;
switch (offset)
{
case 2:
returnValue = (((UInt32) * (pElem + 1)) << 8);
case 1:
returnValue |= (((UInt32) * (pElem)) << 16);
default:
break;
}
}
#else
returnValue = (((UInt32) * (pElem)) << 16) |
(((UInt32) * (pElem + 1)) << 8) |
((UInt32) * (pElem + 2));
#endif
/* Remove extra high bits by shifting up */
bitIndex = (UInt)((pInputStream->usedBits) & INBUF_BIT_MODULO_MASK);
/* This line is faster way to mask off the high bits. */
returnValue = 0xFFFFFF & (returnValue << (bitIndex));
/* Move the field down. */
returnValue = returnValue >> (24 - neededBits);
pInputStream->usedBits += neededBits;
return (returnValue);
}
#ifdef __cplusplus
}
#endif
/*----------------------------------------------------------------------------
; END
----------------------------------------------------------------------------*/
#endif /* GETBITS_H*/
|
