media/libstagefright/codecs/aacdec/getfill.cpp - third_party/android/platform/frameworks/av - Git at Google

 /* ------------------------------------------------------------------
  * 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: getfill.c
  Funtions: getfill

 ------------------------------------------------------------------------------
  REVISION HISTORY

  Description:  Modified from original shareware code

  Description:  Modified to pass variables by reference to eliminate use
                of global variables.

  Description:  1. Used template to re-organize function and filled out
                   Input/Output and Function definition section.
                2. Optimized code.

  Description:  Made the following changes based on review comments.
                1. Exchanging MODIFYING and RETURNING on line 87, 88.
                2. Added MPEG reference.
                3. Changed "fill" to "pass over", "bitstreams are" to
                   "bitstream is" in FUNCTION DESCRIPTION section.
                4. Fixed tabs.

  Description: Replace some instances of getbits to get9_n_lessbits
               when the number of bits read is 9 or less.

  Who:                                   Date:
  Description:

 ------------------------------------------------------------------------------
  INPUT AND OUTPUT DEFINITIONS

  Inputs:
     pInputStream = pointer to structure BITS containing input stream
                    information.

  Local Stores/Buffers/Pointers Needed:
     None

  Global Stores/Buffers/Pointers Needed:
     None

  Outputs:
     None

  Pointers and Buffers Modified:
     pInputStream->usedBits is updated to the newly calculated value.

  Local Stores Modified:
     None

  Global Stores Modified:
     None

 ------------------------------------------------------------------------------
  FUNCTION DESCRIPTION

  This function passes over fill bits in the raw data block to adjust the
  instantaneous bit rate when the bitstream is to be transmitted over a
  constant rate channel.

 ------------------------------------------------------------------------------
  REQUIREMENTS

  None

 ------------------------------------------------------------------------------
  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.

  (2) ISO/IEC 14496-3: 1999(E)
      Subpart 4      p15     (Table 4.4.11)

 ------------------------------------------------------------------------------
  PSEUDO-CODE

     CALL getbits(
             LEN_F_CNT,
             pInputStream);
     MODIFYING (pInputStream)
     RETURNING (cnt)

     IF ( cnt == (1<<LEN_F_CNT)-1 )

         CALL getbits(
                 LEN_F_ESC,
                 pInputStream);
         MODIFYING (pInputStream)
         RETURNING (esc_cnt)

         cnt +=  esc_cnt - 1;

     ENDIF

     pInputStream->usedBits += cnt * LEN_BYTE;

 ------------------------------------------------------------------------------
  RESOURCES USED
    When the code is written for a specific target processor the
      the resources used should be documented below.

  STACK USAGE: [stack count for this module] + [variable to represent
         stack usage for each subroutine called]

      where: [stack usage variable] = stack usage for [subroutine
         name] (see [filename].ext)

  DATA MEMORY USED: x words

  PROGRAM MEMORY USED: x words

  CLOCK CYCLES: [cycle count equation for this module] + [variable
            used to represent cycle count for each subroutine
            called]

      where: [cycle count variable] = cycle count for [subroutine
         name] (see [filename].ext)

 ------------------------------------------------------------------------------
 */

 /*----------------------------------------------------------------------------
 ; INCLUDES
 ----------------------------------------------------------------------------*/
 #include "pv_audio_type_defs.h"
 #include "s_bits.h"
 #include "ibstream.h"
 #include "e_rawbitstreamconst.h"
 #include "getfill.h"

 /*----------------------------------------------------------------------------
 ; MACROS
 ; Define module specific macros here
 ----------------------------------------------------------------------------*/

 /*----------------------------------------------------------------------------
 ; DEFINES
 ; Include all pre-processor statements here. Include conditional
 ; compile variables also.
 ----------------------------------------------------------------------------*/

 /*----------------------------------------------------------------------------
 ; 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 GLOBAL STORE/BUFFER/POINTER REFERENCES
 ; Declare variables used in this module but defined elsewhere
 ----------------------------------------------------------------------------*/

 /*----------------------------------------------------------------------------
 ; FUNCTION CODE
 ----------------------------------------------------------------------------*/

 void getfill(BITS *pInputStream)
 {
     /*----------------------------------------------------------------------------
     ; Define all local variables
     ----------------------------------------------------------------------------*/
     Int cnt;
     Int esc_cnt;

     /*----------------------------------------------------------------------------
     ; Function body here
     ----------------------------------------------------------------------------*/

     cnt = get9_n_lessbits(
               LEN_F_CNT,
               pInputStream);

     if (cnt == (1 << LEN_F_CNT) - 1)  /* if (cnt == 15) */
     {
         esc_cnt = get9_n_lessbits(
                       LEN_F_ESC,
                       pInputStream);

         cnt +=  esc_cnt - 1;
     }

     /*
      * The following codes are replaced by directly updating usedBits
      * in BITS structure. This will save one call for getbits().
      *
      * for (i=0; i<cnt; i++)
      * { getbits(LEN_BYTE, pInputStream); }
      */

     pInputStream->usedBits += cnt * LEN_BYTE;

     /*----------------------------------------------------------------------------
     ; Return nothing or data or data pointer
     ----------------------------------------------------------------------------*/

 } /* getfill */
	/* ------------------------------------------------------------------
	* 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: getfill.c
	Funtions: getfill

	------------------------------------------------------------------------------
	REVISION HISTORY

	Description: Modified from original shareware code

	Description: Modified to pass variables by reference to eliminate use
	of global variables.

	Description: 1. Used template to re-organize function and filled out
	Input/Output and Function definition section.
	2. Optimized code.

	Description: Made the following changes based on review comments.
	1. Exchanging MODIFYING and RETURNING on line 87, 88.
	2. Added MPEG reference.
	3. Changed "fill" to "pass over", "bitstreams are" to
	"bitstream is" in FUNCTION DESCRIPTION section.
	4. Fixed tabs.

	Description: Replace some instances of getbits to get9_n_lessbits
	when the number of bits read is 9 or less.

	Who: Date:
	Description:

	------------------------------------------------------------------------------
	INPUT AND OUTPUT DEFINITIONS

	Inputs:
	pInputStream = pointer to structure BITS containing input stream
	information.

	Local Stores/Buffers/Pointers Needed:
	None

	Global Stores/Buffers/Pointers Needed:
	None

	Outputs:
	None

	Pointers and Buffers Modified:
	pInputStream->usedBits is updated to the newly calculated value.

	Local Stores Modified:
	None

	Global Stores Modified:
	None

	------------------------------------------------------------------------------
	FUNCTION DESCRIPTION

	This function passes over fill bits in the raw data block to adjust the
	instantaneous bit rate when the bitstream is to be transmitted over a
	constant rate channel.

	------------------------------------------------------------------------------
	REQUIREMENTS

	None

	------------------------------------------------------------------------------
	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.

	(2) ISO/IEC 14496-3: 1999(E)
	Subpart 4 p15 (Table 4.4.11)

	------------------------------------------------------------------------------
	PSEUDO-CODE

	CALL getbits(
	LEN_F_CNT,
	pInputStream);
	MODIFYING (pInputStream)
	RETURNING (cnt)

	IF ( cnt == (1<<LEN_F_CNT)-1 )

	CALL getbits(
	LEN_F_ESC,
	pInputStream);
	MODIFYING (pInputStream)
	RETURNING (esc_cnt)

	cnt += esc_cnt - 1;

	ENDIF

	pInputStream->usedBits += cnt * LEN_BYTE;

	------------------------------------------------------------------------------
	RESOURCES USED
	When the code is written for a specific target processor the
	the resources used should be documented below.

	STACK USAGE: [stack count for this module] + [variable to represent
	stack usage for each subroutine called]

	where: [stack usage variable] = stack usage for [subroutine
	name] (see [filename].ext)

	DATA MEMORY USED: x words

	PROGRAM MEMORY USED: x words

	CLOCK CYCLES: [cycle count equation for this module] + [variable
	used to represent cycle count for each subroutine
	called]

	where: [cycle count variable] = cycle count for [subroutine
	name] (see [filename].ext)

	------------------------------------------------------------------------------
	*/

	/*----------------------------------------------------------------------------
	; INCLUDES
	----------------------------------------------------------------------------*/
	#include "pv_audio_type_defs.h"
	#include "s_bits.h"
	#include "ibstream.h"
	#include "e_rawbitstreamconst.h"
	#include "getfill.h"

	/*----------------------------------------------------------------------------
	; MACROS
	; Define module specific macros here
	----------------------------------------------------------------------------*/

	/*----------------------------------------------------------------------------
	; DEFINES
	; Include all pre-processor statements here. Include conditional
	; compile variables also.
	----------------------------------------------------------------------------*/

	/*----------------------------------------------------------------------------
	; 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 GLOBAL STORE/BUFFER/POINTER REFERENCES
	; Declare variables used in this module but defined elsewhere
	----------------------------------------------------------------------------*/

	/*----------------------------------------------------------------------------
	; FUNCTION CODE
	----------------------------------------------------------------------------*/

	void getfill(BITS *pInputStream)
	{
	/*----------------------------------------------------------------------------
	; Define all local variables
	----------------------------------------------------------------------------*/
	Int cnt;
	Int esc_cnt;

	/*----------------------------------------------------------------------------
	; Function body here
	----------------------------------------------------------------------------*/

	cnt = get9_n_lessbits(
	LEN_F_CNT,
	pInputStream);

	if (cnt == (1 << LEN_F_CNT) - 1) /* if (cnt == 15) */
	{
	esc_cnt = get9_n_lessbits(
	LEN_F_ESC,
	pInputStream);

	cnt += esc_cnt - 1;
	}

	/*
	* The following codes are replaced by directly updating usedBits
	* in BITS structure. This will save one call for getbits().
	*
	* for (i=0; i<cnt; i++)
	* { getbits(LEN_BYTE, pInputStream); }
	*/

	pInputStream->usedBits += cnt * LEN_BYTE;

	/*----------------------------------------------------------------------------
	; Return nothing or data or data pointer
	----------------------------------------------------------------------------*/

	} /* getfill */