1 /* ------------------------------------------------------------------ 2 * Copyright (C) 1998-2009 PacketVideo 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either 13 * express or implied. 14 * See the License for the specific language governing permissions 15 * and limitations under the License. 16 * ------------------------------------------------------------------- 17 */ 18 /* 19 20 Filename: sbr_crc_check.c 21 22 ------------------------------------------------------------------------------ 23 REVISION HISTORY 24 25 26 Who: Date: MM/DD/YYYY 27 Description: 28 29 ------------------------------------------------------------------------------ 30 INPUT AND OUTPUT DEFINITIONS 31 32 33 ------------------------------------------------------------------------------ 34 FUNCTION DESCRIPTION 35 36 37 ------------------------------------------------------------------------------ 38 REQUIREMENTS 39 40 41 ------------------------------------------------------------------------------ 42 REFERENCES 43 44 SC 29 Software Copyright Licencing Disclaimer: 45 46 This software module was originally developed by 47 Coding Technologies 48 49 and edited by 50 - 51 52 in the course of development of the ISO/IEC 13818-7 and ISO/IEC 14496-3 53 standards for reference purposes and its performance may not have been 54 optimized. This software module is an implementation of one or more tools as 55 specified by the ISO/IEC 13818-7 and ISO/IEC 14496-3 standards. 56 ISO/IEC gives users free license to this software module or modifications 57 thereof for use in products claiming conformance to audiovisual and 58 image-coding related ITU Recommendations and/or ISO/IEC International 59 Standards. ISO/IEC gives users the same free license to this software module or 60 modifications thereof for research purposes and further ISO/IEC standardisation. 61 Those intending to use this software module in products are advised that its 62 use may infringe existing patents. ISO/IEC have no liability for use of this 63 software module or modifications thereof. Copyright is not released for 64 products that do not conform to audiovisual and image-coding related ITU 65 Recommendations and/or ISO/IEC International Standards. 66 The original developer retains full right to modify and use the code for its 67 own purpose, assign or donate the code to a third party and to inhibit third 68 parties from using the code for products that do not conform to audiovisual and 69 image-coding related ITU Recommendations and/or ISO/IEC International Standards. 70 This copyright notice must be included in all copies or derivative works. 71 Copyright (c) ISO/IEC 2002. 72 73 ------------------------------------------------------------------------------ 74 PSEUDO-CODE 75 76 ------------------------------------------------------------------------------ 77 */ 78 79 80 /*---------------------------------------------------------------------------- 81 ; INCLUDES 82 ----------------------------------------------------------------------------*/ 83 84 #ifdef AAC_PLUS 85 86 87 #include "sbr_crc_check.h" 88 #include "s_crc_buffer.h" 89 #include "buf_getbits.h" 90 #include "sbr_constants.h" 91 #include "check_crc.h" 92 93 94 95 96 /*---------------------------------------------------------------------------- 97 ; MACROS 98 ; Define module specific macros here 99 ----------------------------------------------------------------------------*/ 100 101 102 /*---------------------------------------------------------------------------- 103 ; DEFINES 104 ; Include all pre-processor statements here. Include conditional 105 ; compile variables also. 106 ----------------------------------------------------------------------------*/ 107 108 /*---------------------------------------------------------------------------- 109 ; LOCAL FUNCTION DEFINITIONS 110 ; Function Prototype declaration 111 ----------------------------------------------------------------------------*/ 112 113 /*---------------------------------------------------------------------------- 114 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 115 ; Variable declaration - defined here and used outside this module 116 ----------------------------------------------------------------------------*/ 117 118 const unsigned short MAXCRCSTEP = 16; 119 120 /*---------------------------------------------------------------------------- 121 ; EXTERNAL FUNCTION REFERENCES 122 ; Declare functions defined elsewhere and referenced in this module 123 ----------------------------------------------------------------------------*/ 124 125 /*---------------------------------------------------------------------------- 126 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 127 ; Declare variables used in this module but defined elsewhere 128 ----------------------------------------------------------------------------*/ 129 130 /*---------------------------------------------------------------------------- 131 ; FUNCTION CODE 132 ----------------------------------------------------------------------------*/ 133 134 Int32 sbr_crc_check(BIT_BUFFER * hBitBuf, UInt32 NrBits) 135 { 136 Int32 crcResult = 1; 137 BIT_BUFFER BitBufferCRC; 138 UInt32 NrCrcBits; 139 140 UInt32 crcCheckSum; 141 142 Int32 i; 143 CRC_BUFFER CrcBuf; 144 UInt32 bValue; 145 Int32 CrcStep; 146 Int32 CrcNrBitsRest; 147 148 crcCheckSum = buf_getbits(hBitBuf, SI_SBR_CRC_BITS); 149 150 151 /* 152 * Copy Bit buffer State 153 */ 154 155 BitBufferCRC.char_ptr = hBitBuf->char_ptr; 156 BitBufferCRC.buffer_word = hBitBuf->buffer_word; 157 BitBufferCRC.buffered_bits = hBitBuf->buffered_bits; 158 BitBufferCRC.nrBitsRead = hBitBuf->nrBitsRead; 159 BitBufferCRC.bufferLen = hBitBuf->bufferLen; 160 161 162 NrCrcBits = min(NrBits, BitBufferCRC.bufferLen - BitBufferCRC.nrBitsRead); 163 164 165 CrcStep = NrCrcBits / MAXCRCSTEP; 166 CrcNrBitsRest = (NrCrcBits - CrcStep * MAXCRCSTEP); 167 168 CrcBuf.crcState = CRCSTART; 169 CrcBuf.crcMask = CRCMASK; 170 CrcBuf.crcPoly = CRCPOLY; 171 172 for (i = 0; i < CrcStep; i++) 173 { 174 bValue = buf_getbits(&BitBufferCRC, MAXCRCSTEP); 175 check_crc(&CrcBuf, bValue, MAXCRCSTEP); 176 } 177 178 bValue = buf_getbits(&BitBufferCRC, CrcNrBitsRest); 179 check_crc(&CrcBuf, bValue, CrcNrBitsRest); 180 181 if ((UInt32)(CrcBuf.crcState & CRCRANGE) != crcCheckSum) 182 { 183 crcResult = 0; 184 } 185 186 return (crcResult); 187 } 188 189 #endif 190 191 192
