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: check_crc.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 INPUT 33 34 35 OUTPUT 36 37 errorCode, noError if successful 38 39------------------------------------------------------------------------------ 40 FUNCTION DESCRIPTION 41 42 43------------------------------------------------------------------------------ 44 REQUIREMENTS 45 46 47------------------------------------------------------------------------------ 48 REFERENCES 49 50SC 29 Software Copyright Licencing Disclaimer: 51 52This software module was originally developed by 53 Coding Technologies 54 55and edited by 56 - 57 58in the course of development of the ISO/IEC 13818-7 and ISO/IEC 14496-3 59standards for reference purposes and its performance may not have been 60optimized. This software module is an implementation of one or more tools as 61specified by the ISO/IEC 13818-7 and ISO/IEC 14496-3 standards. 62ISO/IEC gives users free license to this software module or modifications 63thereof for use in products claiming conformance to audiovisual and 64image-coding related ITU Recommendations and/or ISO/IEC International 65Standards. ISO/IEC gives users the same free license to this software module or 66modifications thereof for research purposes and further ISO/IEC standardisation. 67Those intending to use this software module in products are advised that its 68use may infringe existing patents. ISO/IEC have no liability for use of this 69software module or modifications thereof. Copyright is not released for 70products that do not conform to audiovisual and image-coding related ITU 71Recommendations and/or ISO/IEC International Standards. 72The original developer retains full right to modify and use the code for its 73own purpose, assign or donate the code to a third party and to inhibit third 74parties from using the code for products that do not conform to audiovisual and 75image-coding related ITU Recommendations and/or ISO/IEC International Standards. 76This copyright notice must be included in all copies or derivative works. 77Copyright (c) ISO/IEC 2002. 78 79------------------------------------------------------------------------------ 80 PSEUDO-CODE 81 82------------------------------------------------------------------------------ 83*/ 84 85 86/*---------------------------------------------------------------------------- 87; INCLUDES 88----------------------------------------------------------------------------*/ 89#include "check_crc.h" 90 91/*---------------------------------------------------------------------------- 92; MACROS 93; Define module specific macros here 94----------------------------------------------------------------------------*/ 95 96 97/*---------------------------------------------------------------------------- 98; DEFINES 99; Include all pre-processor statements here. Include conditional 100; compile variables also. 101----------------------------------------------------------------------------*/ 102 103/*---------------------------------------------------------------------------- 104; LOCAL FUNCTION DEFINITIONS 105; Function Prototype declaration 106----------------------------------------------------------------------------*/ 107 108/*---------------------------------------------------------------------------- 109; LOCAL STORE/BUFFER/POINTER DEFINITIONS 110; Variable declaration - defined here and used outside this module 111----------------------------------------------------------------------------*/ 112 113/*---------------------------------------------------------------------------- 114; EXTERNAL FUNCTION REFERENCES 115; Declare functions defined elsewhere and referenced in this module 116----------------------------------------------------------------------------*/ 117 118/*---------------------------------------------------------------------------- 119; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 120; Declare variables used in this module but defined elsewhere 121----------------------------------------------------------------------------*/ 122 123/*---------------------------------------------------------------------------- 124; FUNCTION CODE 125----------------------------------------------------------------------------*/ 126 127void check_crc(HANDLE_CRC hCrcBuf, UInt32 bValue, Int32 nBits) 128{ 129 Int32 i; 130 UInt32 bMask = (1UL << (nBits - 1)); 131 132 for (i = 0; i < nBits; i++, bMask >>= 1) 133 { 134 UInt16 flag = (UInt16)((hCrcBuf->crcState & hCrcBuf->crcMask) ? 1 : 0); 135 UInt16 flag1 = (UInt16)((bMask & bValue) ? 1 : 0); 136 137 flag ^= flag1; 138 hCrcBuf->crcState <<= 1; 139 if (flag) 140 hCrcBuf->crcState ^= hCrcBuf->crcPoly; 141 } 142 143} 144 145