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Diffstat (limited to 'media/libstagefright/codecs/aacdec/byte_align.cpp')
| -rw-r--r-- | media/libstagefright/codecs/aacdec/byte_align.cpp | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/aacdec/byte_align.cpp b/media/libstagefright/codecs/aacdec/byte_align.cpp new file mode 100644 index 0000000..e75c79e --- /dev/null +++ b/media/libstagefright/codecs/aacdec/byte_align.cpp @@ -0,0 +1,179 @@ +/* ------------------------------------------------------------------ + * 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; +} + |