From 168b22f86912a9291c811f5458f5319d06826375 Mon Sep 17 00:00:00 2001 From: Natalia Portillo Date: Mon, 25 Aug 2014 17:20:05 +0100 Subject: [PATCH] Added static CCITT-CRC16 lookup table. Subchannel Q is big-endian. Detect if a CD-Text pack is really a CD-Text pack to not confuse with CD+G packs. An audio disc can have subchannel correct but channel null. Viceversa can happen. Those should be considered correct and not unknown. --- DiscImageChef/Checksums/CDChecksums.cs | 169 ++++++++++++++++--------- 1 file changed, 112 insertions(+), 57 deletions(-) diff --git a/DiscImageChef/Checksums/CDChecksums.cs b/DiscImageChef/Checksums/CDChecksums.cs index 14744fc3..dae65e81 100644 --- a/DiscImageChef/Checksums/CDChecksums.cs +++ b/DiscImageChef/Checksums/CDChecksums.cs @@ -61,15 +61,20 @@ namespace DiscImageChef.Checksums bool? channelStatus = CheckCDSectorChannel(channel); bool? subchannelStatus = CheckCDSectorSubChannel(subchannel); + bool? status = null; - if (channelStatus == null || subchannelStatus == null) - return null; + if (channelStatus == null && subchannelStatus == null) + status = null; if (channelStatus == false || subchannelStatus == false) - return false; + status = false; + if (channelStatus == null && subchannelStatus == true) + status = true; + if (channelStatus == true && subchannelStatus == null) + status = true; if (channelStatus == true && subchannelStatus == true) - return true; + status = true; - return null; + return status; } case 2352: return CheckCDSectorChannel(buffer); @@ -421,80 +426,130 @@ namespace DiscImageChef.Checksums CDTextPack4[j] = (byte)(CDTextPack4[j] | (subchannel[i++] & 0x3F)); } - UInt16 QSubChannelCRC = BitConverter.ToUInt16(QSubChannel, 10); + BigEndianBitConverter.IsLittleEndian = true; + + UInt16 QSubChannelCRC = BigEndianBitConverter.ToUInt16(QSubChannel, 10); byte[] QSubChannelForCRC = new byte[10]; Array.Copy(QSubChannel, 0, QSubChannelForCRC, 0, 10); - byte[] CalculatedQCRCBytes = new byte[2]; - CRC16Context.Data(QSubChannelForCRC, out CalculatedQCRCBytes); - UInt16 CalculatedQCRC = BitConverter.ToUInt16(CalculatedQCRCBytes, 0); + UInt16 CalculatedQCRC = CalculateCCITT_CRC16(QSubChannelForCRC); if (QSubChannelCRC != CalculatedQCRC) { if (MainClass.isDebug) -// Console.WriteLine("DEBUG (CDChecksums): Q subchannel CRC 0x{0:X4}, expected 0x{1:X4}", CalculatedQCRC, QSubChannelCRC); + Console.WriteLine("DEBUG (CDChecksums): Q subchannel CRC 0x{0:X4}, expected 0x{1:X4}", CalculatedQCRC, QSubChannelCRC); status = false; } - UInt16 CDTextPack1CRC = BitConverter.ToUInt16(CDTextPack1, 16); - byte[] CDTextPack1ForCRC = new byte[16]; - Array.Copy(CDTextPack1, 0, CDTextPack1ForCRC, 0, 16); - byte[] CalculatedCDTP1CRCBytes = new byte[2]; - CRC16Context.Data(CDTextPack1ForCRC, out CalculatedCDTP1CRCBytes); - UInt16 CalculatedCDTP1CRC = BitConverter.ToUInt16(CalculatedCDTP1CRCBytes, 0); - - if (CDTextPack1CRC != CalculatedCDTP1CRC && CDTextPack1CRC != 0) + if ((CDTextPack1[0] & 0x80) == 0x80) { - if (MainClass.isDebug) -// Console.WriteLine("DEBUG (CDChecksums): CD-Text Pack 1 CRC 0x{0:X4}, expected 0x{1:X4}", CDTextPack1CRC, CalculatedCDTP1CRC); + UInt16 CDTextPack1CRC = BigEndianBitConverter.ToUInt16(CDTextPack1, 16); + byte[] CDTextPack1ForCRC = new byte[16]; + Array.Copy(CDTextPack1, 0, CDTextPack1ForCRC, 0, 16); + UInt16 CalculatedCDTP1CRC = CalculateCCITT_CRC16(CDTextPack1ForCRC); + + if (CDTextPack1CRC != CalculatedCDTP1CRC && CDTextPack1CRC != 0) + { + if (MainClass.isDebug) + Console.WriteLine("DEBUG (CDChecksums): CD-Text Pack 1 CRC 0x{0:X4}, expected 0x{1:X4}", CDTextPack1CRC, CalculatedCDTP1CRC); status = false; + } } - UInt16 CDTextPack2CRC = BitConverter.ToUInt16(CDTextPack2, 16); - byte[] CDTextPack2ForCRC = new byte[16]; - Array.Copy(CDTextPack2, 0, CDTextPack2ForCRC, 0, 16); - byte[] CalculatedCDTP2CRCBytes = new byte[2]; - CRC16Context.Data(CDTextPack2ForCRC, out CalculatedCDTP2CRCBytes); - UInt16 CalculatedCDTP2CRC = BitConverter.ToUInt16(CalculatedCDTP2CRCBytes, 0); - - if (CDTextPack2CRC != CalculatedCDTP2CRC && CDTextPack2CRC != 0) + if ((CDTextPack2[0] & 0x80) == 0x80) { - if (MainClass.isDebug) -// Console.WriteLine("DEBUG (CDChecksums): CD-Text Pack 2 CRC 0x{0:X4}, expected 0x{1:X4}", CDTextPack2CRC, CalculatedCDTP2CRC); - status = false; + UInt16 CDTextPack2CRC = BigEndianBitConverter.ToUInt16(CDTextPack2, 16); + byte[] CDTextPack2ForCRC = new byte[16]; + Array.Copy(CDTextPack2, 0, CDTextPack2ForCRC, 0, 16); + UInt16 CalculatedCDTP2CRC = CalculateCCITT_CRC16(CDTextPack2ForCRC); + Console.WriteLine("Cyclic CDTP2 0x{0:X4}, Calc CDTP2 0x{1:X4}", CDTextPack2CRC, CalculatedCDTP2CRC); + + if (CDTextPack2CRC != CalculatedCDTP2CRC && CDTextPack2CRC != 0) + { + if (MainClass.isDebug) + Console.WriteLine("DEBUG (CDChecksums): CD-Text Pack 2 CRC 0x{0:X4}, expected 0x{1:X4}", CDTextPack2CRC, CalculatedCDTP2CRC); + status = false; + } } - UInt16 CDTextPack3CRC = BitConverter.ToUInt16(CDTextPack3, 16); - byte[] CDTextPack3ForCRC = new byte[16]; - Array.Copy(CDTextPack3, 0, CDTextPack3ForCRC, 0, 16); - byte[] CalculatedCDTP3CRCBytes = new byte[2]; - CRC16Context.Data(CDTextPack3ForCRC, out CalculatedCDTP3CRCBytes); - UInt16 CalculatedCDTP3CRC = BitConverter.ToUInt16(CalculatedCDTP3CRCBytes, 0); - - if (CDTextPack3CRC != CalculatedCDTP3CRC && CDTextPack3CRC != 0) + if ((CDTextPack3[0] & 0x80) == 0x80) { - if (MainClass.isDebug) -// Console.WriteLine("DEBUG (CDChecksums): CD-Text Pack 3 CRC 0x{0:X4}, expected 0x{1:X4}", CDTextPack3CRC, CalculatedCDTP3CRC); - status = false; + UInt16 CDTextPack3CRC = BigEndianBitConverter.ToUInt16(CDTextPack3, 16); + byte[] CDTextPack3ForCRC = new byte[16]; + Array.Copy(CDTextPack3, 0, CDTextPack3ForCRC, 0, 16); + UInt16 CalculatedCDTP3CRC = CalculateCCITT_CRC16(CDTextPack3ForCRC); + Console.WriteLine("Cyclic CDTP3 0x{0:X4}, Calc CDTP3 0x{1:X4}", CDTextPack3CRC, CalculatedCDTP3CRC); + + if (CDTextPack3CRC != CalculatedCDTP3CRC && CDTextPack3CRC != 0) + { + if (MainClass.isDebug) + Console.WriteLine("DEBUG (CDChecksums): CD-Text Pack 3 CRC 0x{0:X4}, expected 0x{1:X4}", CDTextPack3CRC, CalculatedCDTP3CRC); + status = false; + } } - UInt16 CDTextPack4CRC = BitConverter.ToUInt16(CDTextPack4, 16); - byte[] CDTextPack4ForCRC = new byte[16]; - Array.Copy(CDTextPack4, 0, CDTextPack4ForCRC, 0, 16); - byte[] CalculatedCDTP4CRCBytes = new byte[2]; - CRC16Context.Data(CDTextPack4ForCRC, out CalculatedCDTP4CRCBytes); - UInt16 CalculatedCDTP4CRC = BitConverter.ToUInt16(CalculatedCDTP4CRCBytes, 0); - - if (CDTextPack4CRC != CalculatedCDTP4CRC && CDTextPack4CRC != 0) + if ((CDTextPack4[0] & 0x80) == 0x80) { - if (MainClass.isDebug) -// Console.WriteLine("DEBUG (CDChecksums): CD-Text Pack 4 CRC 0x{0:X4}, expected 0x{1:X4}", CDTextPack4CRC, CalculatedCDTP4CRC); - status = false; + UInt16 CDTextPack4CRC = BigEndianBitConverter.ToUInt16(CDTextPack4, 16); + byte[] CDTextPack4ForCRC = new byte[16]; + Array.Copy(CDTextPack4, 0, CDTextPack4ForCRC, 0, 16); + UInt16 CalculatedCDTP4CRC = CalculateCCITT_CRC16(CDTextPack4ForCRC); + Console.WriteLine("Cyclic CDTP4 0x{0:X4}, Calc CDTP4 0x{1:X4}", CDTextPack4CRC, CalculatedCDTP4CRC); + + if (CDTextPack4CRC != CalculatedCDTP4CRC && CDTextPack4CRC != 0) + { + if (MainClass.isDebug) + Console.WriteLine("DEBUG (CDChecksums): CD-Text Pack 4 CRC 0x{0:X4}, expected 0x{1:X4}", CDTextPack4CRC, CalculatedCDTP4CRC); + status = false; + } } -// return status; - // TODO: Correct CRC poly and seed - // TODO: Detect CD-Text vs CD+G packets - return null; + return status; + } + + static readonly ushort[] CCITT_CRC16Table = { + 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, + 0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, + 0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, + 0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, + 0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, + 0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, + 0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, + 0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, + 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, + 0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, + 0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, + 0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, + 0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, + 0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, + 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, + 0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, + 0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, + 0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, + 0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, + 0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, + 0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, + 0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, + 0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, + 0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, + 0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, + 0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, + 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, + 0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, + 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, + 0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, + 0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, + 0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0, + }; + + static ushort CalculateCCITT_CRC16(byte[] buffer) + { + UInt16 CRC16=0; + for (int i = 0; i < buffer.Length; i++) { + CRC16 = (ushort)(CCITT_CRC16Table[(CRC16 >> 8) ^ buffer[i]] ^ (CRC16 << 8)); + } + CRC16 = (ushort)~CRC16; + + return CRC16; } } }