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🐛Correct CD EDC calcuations.

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This commit is contained in:
Natalia Portillo
2018-04-10 05:07:53 +01:00
parent c93297a225
commit a4faba484a
1 changed files with 45 additions and 46 deletions
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83
CDChecksums.cs
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@@ -42,10 +42,9 @@ namespace DiscImageChef.Checksums
/// </summary>
public static class CdChecksums
{
const uint CDCRC32_POLY = 0xD8018001;
const uint CDCRC32_SEED = 0x00000000;
static byte[] eccFTable;
static byte[] eccBTable;
static uint[] edcTable;
static readonly ushort[] CcittCrc16Table =
{
@@ -109,12 +108,16 @@ namespace DiscImageChef.Checksums
{
eccFTable = new byte[256];
eccBTable = new byte[256];
edcTable = new uint[256];
for(uint i = 0; i < 256; i++)
{
uint edc = i;
uint j = (uint)((i << 1) ^ ((i & 0x80) == 0x80 ? 0x11D : 0));
eccFTable[i] = (byte)j;
eccBTable[i ^ j] = (byte)i;
for(j = 0; j < 8; j++) edc = (edc >> 1) ^ ((edc & 1) > 0 ? 0xD8018001 : 0);
edcTable[i] = edc;
}
}
@@ -131,8 +134,7 @@ namespace DiscImageChef.Checksums
uint minor;
for(minor = 0; minor < minorCount; minor++)
{
byte temp;
temp = index < 4 ? address[index] : data[index - 4];
byte temp = index < 4 ? address[index] : data[index - 4];
index += minorInc;
if(index >= size) index -= size;
eccA ^= temp;
@@ -214,27 +216,23 @@ namespace DiscImageChef.Checksums
"Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC Q check",
channel[0x00C], channel[0x00D], channel[0x00E]);
return !failedEccP && !failedEccQ;
uint storedEdc = BitConverter.ToUInt32(channel, 0x810);
uint calculatedEdc = ComputeEdc(0, channel, 0x810);
/* TODO: This is not working
byte[] SectorForCheck = new byte[0x810];
uint StoredEDC = BitConverter.ToUInt32(channel, 0x810);
byte[] CalculatedEDCBytes;
Array.Copy(channel, 0, SectorForCheck, 0, 0x810);
CRC32Context.Data(SectorForCheck, 0x810, out CalculatedEDCBytes, CDCRC32Poly, CDCRC32Seed);
uint CalculatedEDC = BitConverter.ToUInt32(CalculatedEDCBytes, 0);
if(calculatedEdc == storedEdc) return !failedEccP && !failedEccQ;
if(CalculatedEDC != StoredEDC)
{
DicConsole.DebugWriteLine("CD checksums", "Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, got CRC 0x{3:X8} expected 0x{4:X8}", channel[0x00C], channel[0x00D], channel[0x00E], CalculatedEDC, StoredEDC);
DicConsole.DebugWriteLine("CD checksums",
"Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, got CRC 0x{3:X8} expected 0x{4:X8}",
channel[0x00C], channel[0x00D], channel[0x00E], calculatedEdc, storedEdc);
return false;
}*/
}
if(channel[0x00F] == 0x02) // mode (1 byte)
{
DicConsole.DebugWriteLine("CD checksums", "Mode 2 sector at address {0:X2}:{1:X2}:{2:X2}",
channel[0x00C], channel[0x00D], channel[0x00E]);
//DicConsole.DebugWriteLine("CD checksums", "Mode 2 sector at address {0:X2}:{1:X2}:{2:X2}",
// channel[0x00C], channel[0x00D], channel[0x00E]);
byte[] mode2Sector = new byte[channel.Length - 0x10];
Array.Copy(channel, 0x10, mode2Sector, 0, mode2Sector.Length);
if((channel[0x012] & 0x20) == 0x20) // mode 2 form 2
{
@@ -244,19 +242,18 @@ namespace DiscImageChef.Checksums
"Subheader copies differ in mode 2 form 2 sector at address: {0:X2}:{1:X2}:{2:X2}",
channel[0x00C], channel[0x00D], channel[0x00E]);
/* TODO: This is not working
byte[] SectorForCheck = new byte[0x91C];
uint StoredEDC = BitConverter.ToUInt32(channel, 0x92C);
byte[] CalculatedEDCBytes;
Array.Copy(channel, 0x10, SectorForCheck, 0, 0x91C);
CRC32Context.Data(SectorForCheck, 0x91C, out CalculatedEDCBytes, CDCRC32Poly, CDCRC32Seed);
uint CalculatedEDC = BitConverter.ToUInt32(CalculatedEDCBytes, 0);
uint storedEdc = BitConverter.ToUInt32(mode2Sector, 0x91C);
// No CRC stored!
if(storedEdc == 0x00000000) return true;
if(CalculatedEDC != StoredEDC && StoredEDC != 0x00000000)
{
DicConsole.DebugWriteLine("CD checksums", "Mode 2 form 2 sector at address: {0:X2}:{1:X2}:{2:X2}, got CRC 0x{3:X8} expected 0x{4:X8}", channel[0x00C], channel[0x00D], channel[0x00E], CalculatedEDC, StoredEDC);
uint calculatedEdc = ComputeEdc(0, mode2Sector, 0x91C);
if(calculatedEdc == storedEdc || storedEdc == 0x00000000) return true;
DicConsole.DebugWriteLine("CD checksums",
"Mode 2 form 2 sector at address: {0:X2}:{1:X2}:{2:X2}, got CRC 0x{3:X8} expected 0x{4:X8}",
channel[0x00C], channel[0x00D], channel[0x00E], calculatedEdc, storedEdc);
return false;
}*/
}
else
{
@@ -291,23 +288,17 @@ namespace DiscImageChef.Checksums
if(failedEccQ)
DicConsole.DebugWriteLine("CD checksums",
"Mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC Q check",
channel[0x00F], channel[0x00C], channel[0x00D], channel[0x00E]);
channel[0x00C], channel[0x00D], channel[0x00E]);
return !failedEccP && !failedEccQ;
uint storedEdc = BitConverter.ToUInt32(mode2Sector, 0x808);
uint calculatedEdc = ComputeEdc(0, mode2Sector, 0x808);
/* TODO: This is not working
byte[] SectorForCheck = new byte[0x808];
uint StoredEDC = BitConverter.ToUInt32(channel, 0x818);
byte[] CalculatedEDCBytes;
Array.Copy(channel, 0x10, SectorForCheck, 0, 0x808);
CRC32Context.Data(SectorForCheck, 0x808, out CalculatedEDCBytes, CDCRC32Poly, CDCRC32Seed);
uint CalculatedEDC = BitConverter.ToUInt32(CalculatedEDCBytes, 0);
if(calculatedEdc == storedEdc) return !failedEccP && !failedEccQ;
if(CalculatedEDC != StoredEDC)
{
DicConsole.DebugWriteLine("CD checksums", "Mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}, got CRC 0x{3:X8} expected 0x{4:X8}", channel[0x00C], channel[0x00D], channel[0x00E], CalculatedEDC, StoredEDC);
DicConsole.DebugWriteLine("CD checksums",
"Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, got CRC 0x{3:X8} expected 0x{4:X8}",
channel[0x00C], channel[0x00D], channel[0x00E], calculatedEdc, storedEdc);
return false;
}*/
}
return true;
@@ -318,6 +309,14 @@ namespace DiscImageChef.Checksums
return null;
}
static uint ComputeEdc(uint edc, byte[] src, int size)
{
int pos = 0;
for(; size > 0; size--) edc = (edc >> 8) ^ edcTable[(edc ^ src[pos++]) & 0xFF];
return edc;
}
static bool? CheckCdSectorSubChannel(byte[] subchannel)
{
bool? status = true;