| /* ------------------------------------------------------------------ |
| * 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 |
| |
| Adquire Data Stream element (DSE) from raw bitstream |
| At this time this function just drops the information. |
| |
| ------------------------------------------------------------------------------ |
| 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 "get_dse.h" |
| #include "ibstream.h" |
| #include "getbits.h" |
| #include "s_bits.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 VARIABLES REFERENCES |
| ; Declare variables used in this module but defined elsewhere |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; FUNCTION CODE |
| ----------------------------------------------------------------------------*/ |
| |
| void get_dse( |
| Char *DataStreamBytes, |
| BITS *pInputStream) |
| { |
| Int i; |
| Int data_byte_align_flag; |
| UInt count; |
| Int esc_count; |
| Char *pDataStreamBytes; |
| |
| pDataStreamBytes = DataStreamBytes; |
| |
| /* |
| * Get element instance tag ( 4 bits) |
| * ( max of 16 per raw data block) |
| */ |
| get9_n_lessbits(LEN_TAG, pInputStream); |
| |
| /* |
| * get data_byte_align_flag ( 1 bit0 to see if byte alignment is |
| * performed within the DSE |
| */ |
| data_byte_align_flag = get1bits(pInputStream); |
| |
| /* |
| * get count ( 8 bits) |
| */ |
| count = get9_n_lessbits(LEN_D_CNT, pInputStream); |
| |
| /* |
| * if count == 255, its value it is incremented by a |
| * second 8 bit value, esc_count. This final value represents |
| * the number of bytes in the DSE |
| */ |
| if (count == (1 << LEN_D_CNT) - 1) |
| { |
| esc_count = (Int)get9_n_lessbits(LEN_D_ESC, pInputStream); /* 8 bits */ |
| count += esc_count; |
| } |
| |
| /* |
| * Align if flag is set |
| */ |
| if (data_byte_align_flag) |
| { |
| byte_align(pInputStream); |
| } |
| |
| for (i = count; i != 0; i--) |
| { |
| *(pDataStreamBytes++) = (Char) get9_n_lessbits( |
| LEN_BYTE, |
| pInputStream); |
| } |
| |
| return; |
| |
| } /* end get_dse */ |
| |