| /* ------------------------------------------------------------------ |
| * 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. |
| * ------------------------------------------------------------------- |
| */ |
| /* |
| |
| Filename: buf_getbits.c |
| |
| ------------------------------------------------------------------------------ |
| REVISION HISTORY |
| |
| |
| Who: Date: MM/DD/YYYY |
| Description: |
| |
| ------------------------------------------------------------------------------ |
| INPUT AND OUTPUT DEFINITIONS |
| |
| Arguments: hBitBuf Handle to Bitbuffer |
| n Number of bits to read |
| |
| Return: bits |
| |
| |
| ------------------------------------------------------------------------------ |
| FUNCTION DESCRIPTION |
| |
| Reads n bits from Bitbuffer |
| |
| ------------------------------------------------------------------------------ |
| REQUIREMENTS |
| |
| |
| ------------------------------------------------------------------------------ |
| REFERENCES |
| |
| SC 29 Software Copyright Licencing Disclaimer: |
| |
| This software module was originally developed by |
| Coding Technologies |
| |
| and edited by |
| - |
| |
| in the course of development of the ISO/IEC 13818-7 and ISO/IEC 14496-3 |
| standards for reference purposes and its performance may not have been |
| optimized. This software module is an implementation of one or more tools as |
| specified by the ISO/IEC 13818-7 and ISO/IEC 14496-3 standards. |
| ISO/IEC gives users free license to this software module or modifications |
| thereof for use in products claiming conformance to audiovisual and |
| image-coding related ITU Recommendations and/or ISO/IEC International |
| Standards. ISO/IEC gives users the same free license to this software module or |
| modifications thereof for research purposes and further ISO/IEC standardisation. |
| Those intending to use this software module in products are advised that its |
| use may infringe existing patents. ISO/IEC have no liability for use of this |
| software module or modifications thereof. Copyright is not released for |
| products that do not conform to audiovisual and image-coding related ITU |
| Recommendations and/or ISO/IEC International Standards. |
| The original developer retains full right to modify and use the code for its |
| own purpose, assign or donate the code to a third party and to inhibit third |
| parties from using the code for products that do not conform to audiovisual and |
| image-coding related ITU Recommendations and/or ISO/IEC International Standards. |
| This copyright notice must be included in all copies or derivative works. |
| Copyright (c) ISO/IEC 2002. |
| |
| ------------------------------------------------------------------------------ |
| PSEUDO-CODE |
| |
| ------------------------------------------------------------------------------ |
| */ |
| |
| |
| /*---------------------------------------------------------------------------- |
| ; INCLUDES |
| ----------------------------------------------------------------------------*/ |
| |
| #ifdef AAC_PLUS |
| |
| #include "buf_getbits.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 STORE/BUFFER/POINTER 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 |
| ----------------------------------------------------------------------------*/ |
| |
| UInt32 buf_getbits(BIT_BUFFER * hBitBuf, Int32 n) |
| { |
| |
| /* read bits from MSB side */ |
| if (hBitBuf->buffered_bits <= 16) |
| { |
| hBitBuf->buffer_word = (hBitBuf->buffer_word << 16) | (*(hBitBuf->char_ptr++) << 8); |
| hBitBuf->buffer_word |= *(hBitBuf->char_ptr++); |
| hBitBuf->buffered_bits += 16; |
| } |
| |
| hBitBuf->buffered_bits -= n; |
| hBitBuf->nrBitsRead += n; |
| |
| return ((hBitBuf->buffer_word >> hBitBuf->buffered_bits) & ((1 << n) - 1)); |
| |
| } |
| |
| |
| UInt32 buf_get_1bit(BIT_BUFFER * hBitBuf) |
| { |
| |
| /* read bits from MSB side */ |
| if (hBitBuf->buffered_bits <= 16) |
| { |
| hBitBuf->buffer_word = (hBitBuf->buffer_word << 16) | (*(hBitBuf->char_ptr++) << 8); |
| hBitBuf->buffer_word |= *(hBitBuf->char_ptr++); |
| hBitBuf->buffered_bits += 16; |
| } |
| |
| hBitBuf->buffered_bits--; |
| hBitBuf->nrBitsRead++; |
| |
| return ((hBitBuf->buffer_word >> hBitBuf->buffered_bits) & 1); |
| |
| } |
| |
| #endif |