/*************************************************************************** * Copyright 2005 Raphaƫl Slinckx ****************************************************************************/ /* THIS FILE IS LICENSED UNDER THE MIT LICENSE AS OUTLINED IMMEDIATELY BELOW: * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER * DEALINGS IN THE SOFTWARE. */ namespace Entagged.Audioformats.Ogg.Util { public class OggCRCFactory { private static long[] crc_lookup = new long[256]; private static bool inited = false; public static void Init() { for ( int i = 0; i < 256; i++ ) { long r = i << 24; for ( int j = 0; j < 8; j++ ) if ( ( r & 0x80000000L ) != 0 ) r = ( r << 1 ) ^ 0x04c11db7L; else r <<= 1; crc_lookup[i] = ( r & 0xffffffff ); } inited = true; } public bool CheckCRC( byte[] data, byte[] crc ) { byte[] computedCrc = ComputeCRC(data); if (crc.Length != computedCrc.Length) return false; for (int i = 0; i> 24 ) & 0xff ) ^ (data[i]&0xff) ); crc_reg = ( crc_reg << 8 ) ^ crc_lookup[tmp]; crc_reg &= 0xffffffff; } byte[] sum = new byte[4]; sum[0] = (byte) ( crc_reg & 0xffL ); sum[1] = (byte) ( ( crc_reg >> 8 ) & 0xffL ); sum[2] = (byte) ( ( crc_reg >> 16 ) & 0xffL ); sum[3] = (byte) ( ( crc_reg >> 24 ) & 0xffL ); return sum; } } }