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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.
* -------------------------------------------------------------------
*/
/*
------------------------------------------------------------------------------
INPUT AND OUTPUT DEFINITIONS
Inputs:
pInputStream = pointer to a BITS structure that holds information
regarding the input stream.
Local Stores/Buffers/Pointers Needed:
None
Global Stores/Buffers/Pointers Needed:
None
Outputs:
None
Pointers and Buffers Modified:
pInputStream->usedBits is rounded up to a number that represents the next
byte boundary.
Local Stores Modified:
None
Global Stores Modified:
None
------------------------------------------------------------------------------
FUNCTION DESCRIPTION
Makes the input stream structure pointed to align to the next byte boundary.
If it is already at a byte boundary it is left alone.
------------------------------------------------------------------------------
REQUIREMENTS
This function shall not use global or static variables.
------------------------------------------------------------------------------
REFERENCES
(1) MPEG-2 NBC Audio Decoder
"This software module was originally developed by AT&T, Dolby
Laboratories, Fraunhofer Gesellschaft IIS in the course of development
of the MPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and
3. This software module is an implementation of a part of one or more
MPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4
Audio standard. ISO/IEC gives users of the MPEG-2 NBC/MPEG-4 Audio
standards free license to this software module or modifications thereof
for use in hardware or software products claiming conformance to the
MPEG-2 NBC/MPEG-4 Audio standards. Those intending to use this software
module in hardware or software products are advised that this use may
infringe existing patents. The original developer of this software
module and his/her company, the subsequent editors and their companies,
and ISO/IEC have no liability for use of this software module or
modifications thereof in an implementation. Copyright is not released
for non MPEG-2 NBC/MPEG-4 Audio conforming products.The original
developer retains full right to use the code for his/her own purpose,
assign or donate the code to a third party and to inhibit third party
from using the code for non MPEG-2 NBC/MPEG-4 Audio conforming products.
This copyright notice must be included in all copies or derivative
works."
Copyright(c)1996.
------------------------------------------------------------------------------
PSEUDO-CODE
void byte_align(
BITS *pInputStream)
MODIFYING(pInputStream->usedBits = pInputStream->usedBits +
(pInputStream->usedBits + 7) % 8)
RETURN(nothing)
------------------------------------------------------------------------------
RESOURCES USED
STACK USAGE:
where:
DATA MEMORY USED: x words
PROGRAM MEMORY USED: x words
CLOCK CYCLES:
------------------------------------------------------------------------------
*/
/*----------------------------------------------------------------------------
; INCLUDES
----------------------------------------------------------------------------*/
#include "pv_audio_type_defs.h"
#include "s_bits.h"
#include "ibstream.h"
/*----------------------------------------------------------------------------
; MACROS
; Define module specific macros here
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; DEFINES
; Include all pre-processor statements here. Include conditional
; compile variables also.
----------------------------------------------------------------------------*/
/*
* A negative number was used for this mask so that it works on both
* 16-bit or 32-bit machines. The mask must be cast to unsigned int to
* work with TI compiler, ver 1.80.
*/
#define BYTE_ALIGN_MASK ((UInt)(-8))
#define BYTE_ALIGN_ROUNDUP 7
/*----------------------------------------------------------------------------
; LOCAL FUNCTION DEFINITIONS
; Function Prototype declaration
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; LOCAL VARIABLE DEFINITIONS
; Variable declaration - defined here and used outside this module
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; EXTERNAL FUNCTION REFERENCES
; Declare functions defined elsewhere and referenced in this module
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; EXTERNAL VARIABLES REFERENCES
; Declare variables used in this module but defined elsewhere
----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------
; FUNCTION CODE
----------------------------------------------------------------------------*/
void byte_align(
BITS *pInputStream)
{
/*
* Round up to the next byte by adding 7 and masking off with
* FFF8 or FFFFFFF8. The masking operation is a faster way to
* perform modulo arithmetic if the number is a power of 2.
*
* This code is the same as
* pInputStream->usedBits += (pInputStream->usedBits + 7) % 8
*/
pInputStream->usedBits += BYTE_ALIGN_ROUNDUP;
pInputStream->usedBits &= BYTE_ALIGN_MASK;
return;
}
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