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Diffstat (limited to 'media/libstagefright/codecs/aacdec/getfill.cpp')
| -rw-r--r-- | media/libstagefright/codecs/aacdec/getfill.cpp | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/aacdec/getfill.cpp b/media/libstagefright/codecs/aacdec/getfill.cpp new file mode 100644 index 0000000..3c4fc4c --- /dev/null +++ b/media/libstagefright/codecs/aacdec/getfill.cpp @@ -0,0 +1,247 @@ +/* ------------------------------------------------------------------ + * 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 */ + |