mirror of
https://github.com/aaru-dps/Aaru.Checksums.git
synced 2025-12-16 19:24:29 +00:00
REFACTOR: Invert 'if' statement to reduce nesting.
This commit is contained in:
243
CDChecksums.cs
243
CDChecksums.cs
@@ -124,73 +124,73 @@ namespace DiscImageChef.Checksums
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{
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EccInit();
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if(channel[0x000] == 0x00 && // sync (12 bytes)
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channel[0x001] == 0xFF && channel[0x002] == 0xFF && channel[0x003] == 0xFF && channel[0x004] == 0xFF &&
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channel[0x005] == 0xFF && channel[0x006] == 0xFF && channel[0x007] == 0xFF && channel[0x008] == 0xFF &&
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channel[0x009] == 0xFF && channel[0x00A] == 0xFF && channel[0x00B] == 0x00)
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if(channel[0x000] != 0x00 || channel[0x001] != 0xFF || channel[0x002] != 0xFF || channel[0x003] != 0xFF ||
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channel[0x004] != 0xFF || channel[0x005] != 0xFF || channel[0x006] != 0xFF || channel[0x007] != 0xFF ||
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channel[0x008] != 0xFF || channel[0x009] != 0xFF || channel[0x00A] != 0xFF ||
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channel[0x00B] != 0x00) return null;
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DicConsole.DebugWriteLine("CD checksums", "Data sector, address {0:X2}:{1:X2}:{2:X2}", channel[0x00C],
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channel[0x00D], channel[0x00E]);
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if(channel[0x00F] == 0x00) // mode (1 byte)
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{
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DicConsole.DebugWriteLine("CD checksums", "Data sector, address {0:X2}:{1:X2}:{2:X2}", channel[0x00C],
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channel[0x00D], channel[0x00E]);
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if(channel[0x00F] == 0x00) // mode (1 byte)
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{
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DicConsole.DebugWriteLine("CD checksums", "Mode 0 sector at address {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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for(int i = 0x010; i < 0x930; i++)
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if(channel[i] != 0x00)
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{
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 0 sector with error at address: {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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return false;
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}
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return true;
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}
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if(channel[0x00F] == 0x01) // mode (1 byte)
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{
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DicConsole.DebugWriteLine("CD checksums", "Mode 1 sector at address {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if(channel[0x814] != 0x00 || // reserved (8 bytes)
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channel[0x815] != 0x00 || channel[0x816] != 0x00 || channel[0x817] != 0x00 ||
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channel[0x818] != 0x00 || channel[0x819] != 0x00 || channel[0x81A] != 0x00 ||
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channel[0x81B] != 0x00)
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DicConsole.DebugWriteLine("CD checksums", "Mode 0 sector at address {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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for(int i = 0x010; i < 0x930; i++)
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if(channel[i] != 0x00)
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{
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 1 sector with data in reserved bytes at address: {0:X2}:{1:X2}:{2:X2}",
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"Mode 0 sector with error at address: {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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return false;
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}
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byte[] address = new byte[4];
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byte[] data = new byte[2060];
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byte[] data2 = new byte[2232];
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byte[] eccP = new byte[172];
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byte[] eccQ = new byte[104];
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return true;
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}
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Array.Copy(channel, 0x0C, address, 0, 4);
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Array.Copy(channel, 0x0C, data, 0, 2060);
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Array.Copy(channel, 0x0C, data2, 0, 2232);
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Array.Copy(channel, 0x81C, eccP, 0, 172);
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Array.Copy(channel, 0x8C8, eccQ, 0, 104);
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if(channel[0x00F] == 0x01) // mode (1 byte)
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{
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DicConsole.DebugWriteLine("CD checksums", "Mode 1 sector at address {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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bool failedEccP = CheckEcc(address, data, 86, 24, 2, 86, eccP);
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bool failedEccQ = CheckEcc(address, data2, 52, 43, 86, 88, eccQ);
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if(channel[0x814] != 0x00 || // reserved (8 bytes)
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channel[0x815] != 0x00 || channel[0x816] != 0x00 || channel[0x817] != 0x00 ||
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channel[0x818] != 0x00 || channel[0x819] != 0x00 || channel[0x81A] != 0x00 ||
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channel[0x81B] != 0x00)
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{
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 1 sector with data in reserved bytes at address: {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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return false;
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}
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if(failedEccP)
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC P check",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if(failedEccQ)
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC Q check",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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byte[] address = new byte[4];
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byte[] data = new byte[2060];
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byte[] data2 = new byte[2232];
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byte[] eccP = new byte[172];
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byte[] eccQ = new byte[104];
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if(failedEccP || failedEccQ) return false;
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Array.Copy(channel, 0x0C, address, 0, 4);
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Array.Copy(channel, 0x0C, data, 0, 2060);
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Array.Copy(channel, 0x0C, data2, 0, 2232);
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Array.Copy(channel, 0x81C, eccP, 0, 172);
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Array.Copy(channel, 0x8C8, eccQ, 0, 104);
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/* TODO: This is not working
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bool failedEccP = CheckEcc(address, data, 86, 24, 2, 86, eccP);
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bool failedEccQ = CheckEcc(address, data2, 52, 43, 86, 88, eccQ);
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if(failedEccP)
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC P check",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if(failedEccQ)
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC Q check",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if(failedEccP || failedEccQ) return false;
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/* TODO: This is not working
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byte[] SectorForCheck = new byte[0x810];
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uint StoredEDC = BitConverter.ToUInt32(channel, 0x810);
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byte[] CalculatedEDCBytes;
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@@ -204,23 +204,23 @@ namespace DiscImageChef.Checksums
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return false;
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}*/
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return true;
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}
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return true;
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}
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if(channel[0x00F] == 0x02) // mode (1 byte)
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if(channel[0x00F] == 0x02) // mode (1 byte)
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{
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DicConsole.DebugWriteLine("CD checksums", "Mode 2 sector at address {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if((channel[0x012] & 0x20) == 0x20) // mode 2 form 2
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{
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DicConsole.DebugWriteLine("CD checksums", "Mode 2 sector at address {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if(channel[0x010] != channel[0x014] || channel[0x011] != channel[0x015] ||
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channel[0x012] != channel[0x016] || channel[0x013] != channel[0x017])
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DicConsole.DebugWriteLine("CD checksums",
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"Subheader copies differ in mode 2 form 2 sector at address: {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if((channel[0x012] & 0x20) == 0x20) // mode 2 form 2
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{
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if(channel[0x010] != channel[0x014] || channel[0x011] != channel[0x015] ||
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channel[0x012] != channel[0x016] || channel[0x013] != channel[0x017])
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DicConsole.DebugWriteLine("CD checksums",
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"Subheader copies differ in mode 2 form 2 sector at address: {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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/* TODO: This is not working
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/* TODO: This is not working
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byte[] SectorForCheck = new byte[0x91C];
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uint StoredEDC = BitConverter.ToUInt32(channel, 0x92C);
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byte[] CalculatedEDCBytes;
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@@ -233,45 +233,45 @@ namespace DiscImageChef.Checksums
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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);
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return false;
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}*/
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}
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else
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{
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if(channel[0x010] != channel[0x014] || channel[0x011] != channel[0x015] ||
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channel[0x012] != channel[0x016] || channel[0x013] != channel[0x017])
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DicConsole.DebugWriteLine("CD checksums",
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"Subheader copies differ in mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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}
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else
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{
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if(channel[0x010] != channel[0x014] || channel[0x011] != channel[0x015] ||
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channel[0x012] != channel[0x016] || channel[0x013] != channel[0x017])
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DicConsole.DebugWriteLine("CD checksums",
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"Subheader copies differ in mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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byte[] address = new byte[4];
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byte[] data = new byte[2060];
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byte[] data2 = new byte[2232];
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byte[] eccP = new byte[172];
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byte[] eccQ = new byte[104];
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byte[] address = new byte[4];
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byte[] data = new byte[2060];
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byte[] data2 = new byte[2232];
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byte[] eccP = new byte[172];
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byte[] eccQ = new byte[104];
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address[0] = 0;
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address[1] = 0;
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address[2] = 0;
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address[3] = 0;
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Array.Copy(channel, 0x0C, data, 0, 2060);
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Array.Copy(channel, 0x0C, data2, 0, 2232);
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Array.Copy(channel, 0x80C, eccP, 0, 172);
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Array.Copy(channel, 0x8B8, eccQ, 0, 104);
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address[0] = 0;
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address[1] = 0;
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address[2] = 0;
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address[3] = 0;
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Array.Copy(channel, 0x0C, data, 0, 2060);
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Array.Copy(channel, 0x0C, data2, 0, 2232);
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Array.Copy(channel, 0x80C, eccP, 0, 172);
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Array.Copy(channel, 0x8B8, eccQ, 0, 104);
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bool failedEccP = CheckEcc(address, data, 86, 24, 2, 86, eccP);
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bool failedEccQ = CheckEcc(address, data2, 52, 43, 86, 88, eccQ);
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bool failedEccP = CheckEcc(address, data, 86, 24, 2, 86, eccP);
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bool failedEccQ = CheckEcc(address, data2, 52, 43, 86, 88, eccQ);
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if(failedEccP)
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC P check",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if(failedEccQ)
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC Q check",
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channel[0x00F], channel[0x00C], channel[0x00D], channel[0x00E]);
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if(failedEccP)
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC P check",
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channel[0x00C], channel[0x00D], channel[0x00E]);
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if(failedEccQ)
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DicConsole.DebugWriteLine("CD checksums",
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"Mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC Q check",
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channel[0x00F], channel[0x00C], channel[0x00D], channel[0x00E]);
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if(failedEccP || failedEccQ) return false;
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if(failedEccP || failedEccQ) return false;
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/* TODO: This is not working
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/* TODO: This is not working
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byte[] SectorForCheck = new byte[0x808];
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uint StoredEDC = BitConverter.ToUInt32(channel, 0x818);
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byte[] CalculatedEDCBytes;
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@@ -284,17 +284,14 @@ namespace DiscImageChef.Checksums
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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);
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return false;
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}*/
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}
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return true;
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}
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DicConsole.DebugWriteLine("CD checksums",
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"Unknown mode {0} sector at address: {1:X2}:{2:X2}:{3:X2}",
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channel[0x00F], channel[0x00C], channel[0x00D], channel[0x00E]);
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return null;
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return true;
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}
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DicConsole.DebugWriteLine("CD checksums",
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"Unknown mode {0} sector at address: {1:X2}:{2:X2}:{3:X2}",
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channel[0x00F], channel[0x00C], channel[0x00D], channel[0x00E]);
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return null;
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}
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@@ -478,22 +475,20 @@ namespace DiscImageChef.Checksums
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}
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}
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if((cdTextPack4[0] & 0x80) == 0x80)
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{
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ushort cdTextPack4Crc = BigEndianBitConverter.ToUInt16(cdTextPack4, 16);
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byte[] cdTextPack4ForCrc = new byte[16];
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Array.Copy(cdTextPack4, 0, cdTextPack4ForCrc, 0, 16);
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ushort calculatedCdtp4Crc = CalculateCCITT_CRC16(cdTextPack4ForCrc);
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DicConsole.DebugWriteLine("CD checksums", "Cyclic CDTP4 0x{0:X4}, Calc CDTP4 0x{1:X4}", cdTextPack4Crc,
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calculatedCdtp4Crc);
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if((cdTextPack4[0] & 0x80) != 0x80) return status;
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if(cdTextPack4Crc != calculatedCdtp4Crc && cdTextPack4Crc != 0)
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{
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DicConsole.DebugWriteLine("CD checksums", "CD-Text Pack 4 CRC 0x{0:X4}, expected 0x{1:X4}",
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cdTextPack4Crc, calculatedCdtp4Crc);
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status = false;
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}
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}
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ushort cdTextPack4Crc = BigEndianBitConverter.ToUInt16(cdTextPack4, 16);
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byte[] cdTextPack4ForCrc = new byte[16];
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Array.Copy(cdTextPack4, 0, cdTextPack4ForCrc, 0, 16);
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ushort calculatedCdtp4Crc = CalculateCCITT_CRC16(cdTextPack4ForCrc);
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DicConsole.DebugWriteLine("CD checksums", "Cyclic CDTP4 0x{0:X4}, Calc CDTP4 0x{1:X4}", cdTextPack4Crc,
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calculatedCdtp4Crc);
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if(cdTextPack4Crc == calculatedCdtp4Crc || cdTextPack4Crc == 0) return status;
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DicConsole.DebugWriteLine("CD checksums", "CD-Text Pack 4 CRC 0x{0:X4}, expected 0x{1:X4}",
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cdTextPack4Crc, calculatedCdtp4Crc);
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status = false;
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return status;
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}
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432
ReedSolomon.cs
432
ReedSolomon.cs
@@ -305,41 +305,38 @@ namespace DiscImageChef.Checksums
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/// <param name="bb">Outs parity symbols.</param>
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public int encode_rs(int[] data, out int[] bb)
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{
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if(initialized)
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if(!initialized) throw new UnauthorizedAccessException("Trying to calculate RS without initializing!");
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int i, j;
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int feedback;
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bb = new int[nn - kk];
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Clear(ref bb, nn - kk);
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for(i = kk - 1; i >= 0; i--)
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{
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int i, j;
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int feedback;
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bb = new int[nn - kk];
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if(mm != 8) if(data[i] > nn) return -1; /* Illegal symbol */
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Clear(ref bb, nn - kk);
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for(i = kk - 1; i >= 0; i--)
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feedback = index_of[data[i] ^ bb[nn - kk - 1]];
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if(feedback != a0)
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{
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if(mm != 8) if(data[i] > nn) return -1; /* Illegal symbol */
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/* feedback term is non-zero */
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for(j = nn - kk - 1; j > 0; j--)
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if(gg[j] != a0) bb[j] = bb[j - 1] ^ alpha_to[Modnn(gg[j] + feedback)];
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else bb[j] = bb[j - 1];
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feedback = index_of[data[i] ^ bb[nn - kk - 1]];
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if(feedback != a0)
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{
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/* feedback term is non-zero */
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for(j = nn - kk - 1; j > 0; j--)
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if(gg[j] != a0) bb[j] = bb[j - 1] ^ alpha_to[Modnn(gg[j] + feedback)];
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else bb[j] = bb[j - 1];
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bb[0] = alpha_to[Modnn(gg[0] + feedback)];
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}
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else
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{
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/* feedback term is zero. encoder becomes a
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* single-byte shifter */
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for(j = nn - kk - 1; j > 0; j--) bb[j] = bb[j - 1];
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bb[0] = 0;
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}
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bb[0] = alpha_to[Modnn(gg[0] + feedback)];
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}
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else
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{
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/* feedback term is zero. encoder becomes a
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* single-byte shifter */
|
||||
for(j = nn - kk - 1; j > 0; j--) bb[j] = bb[j - 1];
|
||||
|
||||
return 0;
|
||||
bb[0] = 0;
|
||||
}
|
||||
}
|
||||
|
||||
throw new UnauthorizedAccessException("Trying to calculate RS without initializing!");
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
@@ -364,243 +361,236 @@ namespace DiscImageChef.Checksums
|
||||
/// <param name="noEras">Number of erasures.</param>
|
||||
public int eras_dec_rs(ref int[] data, out int[] erasPos, int noEras)
|
||||
{
|
||||
if(initialized)
|
||||
if(!initialized) throw new UnauthorizedAccessException("Trying to calculate RS without initializing!");
|
||||
|
||||
erasPos = new int[nn - kk];
|
||||
int degLambda, el, degOmega;
|
||||
int i, j, r;
|
||||
int u, q, tmp, num1, num2, den, discrR;
|
||||
int[] recd = new int[nn];
|
||||
int[] lambda = new int[nn - kk + 1]; /* Err+Eras Locator poly */
|
||||
int[] s = new int[nn - kk + 1]; /* syndrome poly */
|
||||
int[] b = new int[nn - kk + 1];
|
||||
int[] t = new int[nn - kk + 1];
|
||||
int[] omega = new int[nn - kk + 1];
|
||||
int[] root = new int[nn - kk];
|
||||
int[] reg = new int[nn - kk + 1];
|
||||
int[] loc = new int[nn - kk];
|
||||
int synError, count;
|
||||
|
||||
/* data[] is in polynomial form, copy and convert to index form */
|
||||
for(i = nn - 1; i >= 0; i--)
|
||||
{
|
||||
erasPos = new int[nn - kk];
|
||||
int degLambda, el, degOmega;
|
||||
int i, j, r;
|
||||
int u, q, tmp, num1, num2, den, discrR;
|
||||
int[] recd = new int[nn];
|
||||
int[] lambda = new int[nn - kk + 1]; /* Err+Eras Locator poly */
|
||||
int[] s = new int[nn - kk + 1]; /* syndrome poly */
|
||||
int[] b = new int[nn - kk + 1];
|
||||
int[] t = new int[nn - kk + 1];
|
||||
int[] omega = new int[nn - kk + 1];
|
||||
int[] root = new int[nn - kk];
|
||||
int[] reg = new int[nn - kk + 1];
|
||||
int[] loc = new int[nn - kk];
|
||||
int synError, count;
|
||||
if(mm != 8) if(data[i] > nn) return -1; /* Illegal symbol */
|
||||
|
||||
/* data[] is in polynomial form, copy and convert to index form */
|
||||
for(i = nn - 1; i >= 0; i--)
|
||||
{
|
||||
if(mm != 8) if(data[i] > nn) return -1; /* Illegal symbol */
|
||||
|
||||
recd[i] = index_of[data[i]];
|
||||
}
|
||||
/* first form the syndromes; i.e., evaluate recd(x) at roots of g(x)
|
||||
recd[i] = index_of[data[i]];
|
||||
}
|
||||
/* first form the syndromes; i.e., evaluate recd(x) at roots of g(x)
|
||||
* namely @**(B0+i), i = 0, ... ,(NN-KK-1)
|
||||
*/
|
||||
synError = 0;
|
||||
for(i = 1; i <= nn - kk; i++)
|
||||
{
|
||||
tmp = 0;
|
||||
for(j = 0; j < nn; j++)
|
||||
if(recd[j] != a0) /* recd[j] in index form */
|
||||
tmp ^= alpha_to[Modnn(recd[j] + (B0 + i - 1) * j)];
|
||||
synError = 0;
|
||||
for(i = 1; i <= nn - kk; i++)
|
||||
{
|
||||
tmp = 0;
|
||||
for(j = 0; j < nn; j++)
|
||||
if(recd[j] != a0) /* recd[j] in index form */
|
||||
tmp ^= alpha_to[Modnn(recd[j] + (B0 + i - 1) * j)];
|
||||
|
||||
synError |= tmp; /* set flag if non-zero syndrome =>
|
||||
synError |= tmp; /* set flag if non-zero syndrome =>
|
||||
* error */
|
||||
/* store syndrome in index form */
|
||||
s[i] = index_of[tmp];
|
||||
}
|
||||
/* store syndrome in index form */
|
||||
s[i] = index_of[tmp];
|
||||
}
|
||||
|
||||
if(synError == 0) return 0;
|
||||
if(synError == 0) return 0;
|
||||
|
||||
Clear(ref lambda, nn - kk);
|
||||
lambda[0] = 1;
|
||||
if(noEras > 0)
|
||||
Clear(ref lambda, nn - kk);
|
||||
lambda[0] = 1;
|
||||
if(noEras > 0)
|
||||
{
|
||||
/* Init lambda to be the erasure locator polynomial */
|
||||
lambda[1] = alpha_to[erasPos[0]];
|
||||
for(i = 1; i < noEras; i++)
|
||||
{
|
||||
/* Init lambda to be the erasure locator polynomial */
|
||||
lambda[1] = alpha_to[erasPos[0]];
|
||||
for(i = 1; i < noEras; i++)
|
||||
u = erasPos[i];
|
||||
for(j = i + 1; j > 0; j--)
|
||||
{
|
||||
u = erasPos[i];
|
||||
for(j = i + 1; j > 0; j--)
|
||||
{
|
||||
tmp = index_of[lambda[j - 1]];
|
||||
if(tmp != a0) lambda[j] ^= alpha_to[Modnn(u + tmp)];
|
||||
}
|
||||
tmp = index_of[lambda[j - 1]];
|
||||
if(tmp != a0) lambda[j] ^= alpha_to[Modnn(u + tmp)];
|
||||
}
|
||||
}
|
||||
|
||||
#if DEBUG
|
||||
/* find roots of the erasure location polynomial */
|
||||
for(i = 1; i <= noEras; i++) reg[i] = index_of[lambda[i]];
|
||||
/* find roots of the erasure location polynomial */
|
||||
for(i = 1; i <= noEras; i++) reg[i] = index_of[lambda[i]];
|
||||
|
||||
count = 0;
|
||||
for(i = 1; i <= nn; i++)
|
||||
{
|
||||
q = 1;
|
||||
for(j = 1; j <= noEras; j++)
|
||||
if(reg[j] != a0)
|
||||
{
|
||||
reg[j] = Modnn(reg[j] + j);
|
||||
q ^= alpha_to[reg[j]];
|
||||
}
|
||||
|
||||
if(q == 0)
|
||||
{
|
||||
/* store root and error location
|
||||
* number indices
|
||||
*/
|
||||
root[count] = i;
|
||||
loc[count] = nn - i;
|
||||
count++;
|
||||
}
|
||||
}
|
||||
|
||||
if(count != noEras)
|
||||
{
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n lambda(x) is WRONG\n");
|
||||
return -1;
|
||||
}
|
||||
|
||||
DicConsole.DebugWriteLine("Reed Solomon",
|
||||
"\n Erasure positions as determined by roots of Eras Loc Poly:\n");
|
||||
for(i = 0; i < count; i++) DicConsole.DebugWriteLine("Reed Solomon", "{0} ", loc[i]);
|
||||
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n");
|
||||
#endif
|
||||
}
|
||||
|
||||
for(i = 0; i < nn - kk + 1; i++) b[i] = index_of[lambda[i]];
|
||||
|
||||
/*
|
||||
* Begin Berlekamp-Massey algorithm to determine error+erasure
|
||||
* locator polynomial
|
||||
*/
|
||||
r = noEras;
|
||||
el = noEras;
|
||||
while(++r <= nn - kk)
|
||||
{
|
||||
/* r is the step number */
|
||||
/* Compute discrepancy at the r-th step in poly-form */
|
||||
discrR = 0;
|
||||
for(i = 0; i < r; i++) if(lambda[i] != 0 && s[r - i] != a0) discrR ^= alpha_to[Modnn(index_of[lambda[i]] + s[r - i])];
|
||||
|
||||
discrR = index_of[discrR]; /* Index form */
|
||||
if(discrR == a0)
|
||||
{
|
||||
/* 2 lines below: B(x) <-- x*B(x) */
|
||||
Copydown(ref b, ref b, nn - kk);
|
||||
b[0] = a0;
|
||||
}
|
||||
else
|
||||
{
|
||||
/* 7 lines below: T(x) <-- lambda(x) - discr_r*x*b(x) */
|
||||
t[0] = lambda[0];
|
||||
for(i = 0; i < nn - kk; i++)
|
||||
if(b[i] != a0) t[i + 1] = lambda[i + 1] ^ alpha_to[Modnn(discrR + b[i])];
|
||||
else t[i + 1] = lambda[i + 1];
|
||||
|
||||
if(2 * el <= r + noEras - 1)
|
||||
{
|
||||
el = r + noEras - el;
|
||||
/*
|
||||
* 2 lines below: B(x) <-- inv(discr_r) *
|
||||
* lambda(x)
|
||||
*/
|
||||
for(i = 0; i <= nn - kk; i++)
|
||||
b[i] = lambda[i] == 0 ? a0 : Modnn(index_of[lambda[i]] - discrR + nn);
|
||||
}
|
||||
else
|
||||
{
|
||||
/* 2 lines below: B(x) <-- x*B(x) */
|
||||
Copydown(ref b, ref b, nn - kk);
|
||||
b[0] = a0;
|
||||
}
|
||||
|
||||
Copy(ref lambda, ref t, nn - kk + 1);
|
||||
}
|
||||
}
|
||||
|
||||
/* Convert lambda to index form and compute deg(lambda(x)) */
|
||||
degLambda = 0;
|
||||
for(i = 0; i < nn - kk + 1; i++)
|
||||
{
|
||||
lambda[i] = index_of[lambda[i]];
|
||||
if(lambda[i] != a0) degLambda = i;
|
||||
}
|
||||
/*
|
||||
* Find roots of the error+erasure locator polynomial. By Chien
|
||||
* Search
|
||||
*/
|
||||
int temp = reg[0];
|
||||
Copy(ref reg, ref lambda, nn - kk);
|
||||
reg[0] = temp;
|
||||
count = 0; /* Number of roots of lambda(x) */
|
||||
count = 0;
|
||||
for(i = 1; i <= nn; i++)
|
||||
{
|
||||
q = 1;
|
||||
for(j = degLambda; j > 0; j--)
|
||||
for(j = 1; j <= noEras; j++)
|
||||
if(reg[j] != a0)
|
||||
{
|
||||
reg[j] = Modnn(reg[j] + j);
|
||||
q ^= alpha_to[reg[j]];
|
||||
}
|
||||
|
||||
if(q == 0)
|
||||
{
|
||||
/* store root (index-form) and error location number */
|
||||
root[count] = i;
|
||||
loc[count] = nn - i;
|
||||
count++;
|
||||
}
|
||||
if(q != 0) continue;
|
||||
/* store root and error location
|
||||
* number indices
|
||||
*/
|
||||
root[count] = i;
|
||||
loc[count] = nn - i;
|
||||
count++;
|
||||
}
|
||||
|
||||
#if DEBUG
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n Final error positions:\t");
|
||||
if(count != noEras)
|
||||
{
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n lambda(x) is WRONG\n");
|
||||
return -1;
|
||||
}
|
||||
|
||||
DicConsole.DebugWriteLine("Reed Solomon",
|
||||
"\n Erasure positions as determined by roots of Eras Loc Poly:\n");
|
||||
for(i = 0; i < count; i++) DicConsole.DebugWriteLine("Reed Solomon", "{0} ", loc[i]);
|
||||
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n");
|
||||
#endif
|
||||
}
|
||||
|
||||
if(degLambda != count) return -1;
|
||||
/*
|
||||
for(i = 0; i < nn - kk + 1; i++) b[i] = index_of[lambda[i]];
|
||||
|
||||
/*
|
||||
* Begin Berlekamp-Massey algorithm to determine error+erasure
|
||||
* locator polynomial
|
||||
*/
|
||||
r = noEras;
|
||||
el = noEras;
|
||||
while(++r <= nn - kk)
|
||||
{
|
||||
/* r is the step number */
|
||||
/* Compute discrepancy at the r-th step in poly-form */
|
||||
discrR = 0;
|
||||
for(i = 0; i < r; i++) if(lambda[i] != 0 && s[r - i] != a0) discrR ^= alpha_to[Modnn(index_of[lambda[i]] + s[r - i])];
|
||||
|
||||
discrR = index_of[discrR]; /* Index form */
|
||||
if(discrR == a0)
|
||||
{
|
||||
/* 2 lines below: B(x) <-- x*B(x) */
|
||||
Copydown(ref b, ref b, nn - kk);
|
||||
b[0] = a0;
|
||||
}
|
||||
else
|
||||
{
|
||||
/* 7 lines below: T(x) <-- lambda(x) - discr_r*x*b(x) */
|
||||
t[0] = lambda[0];
|
||||
for(i = 0; i < nn - kk; i++)
|
||||
if(b[i] != a0) t[i + 1] = lambda[i + 1] ^ alpha_to[Modnn(discrR + b[i])];
|
||||
else t[i + 1] = lambda[i + 1];
|
||||
|
||||
if(2 * el <= r + noEras - 1)
|
||||
{
|
||||
el = r + noEras - el;
|
||||
/*
|
||||
* 2 lines below: B(x) <-- inv(discr_r) *
|
||||
* lambda(x)
|
||||
*/
|
||||
for(i = 0; i <= nn - kk; i++)
|
||||
b[i] = lambda[i] == 0 ? a0 : Modnn(index_of[lambda[i]] - discrR + nn);
|
||||
}
|
||||
else
|
||||
{
|
||||
/* 2 lines below: B(x) <-- x*B(x) */
|
||||
Copydown(ref b, ref b, nn - kk);
|
||||
b[0] = a0;
|
||||
}
|
||||
|
||||
Copy(ref lambda, ref t, nn - kk + 1);
|
||||
}
|
||||
}
|
||||
|
||||
/* Convert lambda to index form and compute deg(lambda(x)) */
|
||||
degLambda = 0;
|
||||
for(i = 0; i < nn - kk + 1; i++)
|
||||
{
|
||||
lambda[i] = index_of[lambda[i]];
|
||||
if(lambda[i] != a0) degLambda = i;
|
||||
}
|
||||
/*
|
||||
* Find roots of the error+erasure locator polynomial. By Chien
|
||||
* Search
|
||||
*/
|
||||
int temp = reg[0];
|
||||
Copy(ref reg, ref lambda, nn - kk);
|
||||
reg[0] = temp;
|
||||
count = 0; /* Number of roots of lambda(x) */
|
||||
for(i = 1; i <= nn; i++)
|
||||
{
|
||||
q = 1;
|
||||
for(j = degLambda; j > 0; j--)
|
||||
if(reg[j] != a0)
|
||||
{
|
||||
reg[j] = Modnn(reg[j] + j);
|
||||
q ^= alpha_to[reg[j]];
|
||||
}
|
||||
|
||||
if(q != 0) continue;
|
||||
/* store root (index-form) and error location number */
|
||||
root[count] = i;
|
||||
loc[count] = nn - i;
|
||||
count++;
|
||||
}
|
||||
|
||||
#if DEBUG
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n Final error positions:\t");
|
||||
for(i = 0; i < count; i++) DicConsole.DebugWriteLine("Reed Solomon", "{0} ", loc[i]);
|
||||
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n");
|
||||
#endif
|
||||
|
||||
if(degLambda != count) return -1;
|
||||
/*
|
||||
* Compute err+eras evaluator poly omega(x) = s(x)*lambda(x) (modulo
|
||||
* x**(NN-KK)). in index form. Also find deg(omega).
|
||||
*/
|
||||
degOmega = 0;
|
||||
for(i = 0; i < nn - kk; i++)
|
||||
{
|
||||
tmp = 0;
|
||||
j = degLambda < i ? degLambda : i;
|
||||
for(; j >= 0; j--) if(s[i + 1 - j] != a0 && lambda[j] != a0) tmp ^= alpha_to[Modnn(s[i + 1 - j] + lambda[j])];
|
||||
degOmega = 0;
|
||||
for(i = 0; i < nn - kk; i++)
|
||||
{
|
||||
tmp = 0;
|
||||
j = degLambda < i ? degLambda : i;
|
||||
for(; j >= 0; j--) if(s[i + 1 - j] != a0 && lambda[j] != a0) tmp ^= alpha_to[Modnn(s[i + 1 - j] + lambda[j])];
|
||||
|
||||
if(tmp != 0) degOmega = i;
|
||||
omega[i] = index_of[tmp];
|
||||
}
|
||||
if(tmp != 0) degOmega = i;
|
||||
omega[i] = index_of[tmp];
|
||||
}
|
||||
|
||||
omega[nn - kk] = a0;
|
||||
omega[nn - kk] = a0;
|
||||
|
||||
/*
|
||||
/*
|
||||
* Compute error values in poly-form. num1 = omega(inv(X(l))), num2 =
|
||||
* inv(X(l))**(B0-1) and den = lambda_pr(inv(X(l))) all in poly-form
|
||||
*/
|
||||
for(j = count - 1; j >= 0; j--)
|
||||
for(j = count - 1; j >= 0; j--)
|
||||
{
|
||||
num1 = 0;
|
||||
for(i = degOmega; i >= 0; i--) if(omega[i] != a0) num1 ^= alpha_to[Modnn(omega[i] + i * root[j])];
|
||||
|
||||
num2 = alpha_to[Modnn(root[j] * (B0 - 1) + nn)];
|
||||
den = 0;
|
||||
|
||||
/* lambda[i+1] for i even is the formal derivative lambda_pr of lambda[i] */
|
||||
for(i = Min(degLambda, nn - kk - 1) & ~1; i >= 0; i -= 2) if(lambda[i + 1] != a0) den ^= alpha_to[Modnn(lambda[i + 1] + i * root[j])];
|
||||
|
||||
if(den == 0)
|
||||
{
|
||||
num1 = 0;
|
||||
for(i = degOmega; i >= 0; i--) if(omega[i] != a0) num1 ^= alpha_to[Modnn(omega[i] + i * root[j])];
|
||||
|
||||
num2 = alpha_to[Modnn(root[j] * (B0 - 1) + nn)];
|
||||
den = 0;
|
||||
|
||||
/* lambda[i+1] for i even is the formal derivative lambda_pr of lambda[i] */
|
||||
for(i = Min(degLambda, nn - kk - 1) & ~1; i >= 0; i -= 2) if(lambda[i + 1] != a0) den ^= alpha_to[Modnn(lambda[i + 1] + i * root[j])];
|
||||
|
||||
if(den == 0)
|
||||
{
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n ERROR: denominator = 0\n");
|
||||
return -1;
|
||||
}
|
||||
/* Apply error to data */
|
||||
if(num1 != 0) data[loc[j]] ^= alpha_to[Modnn(index_of[num1] + index_of[num2] + nn - index_of[den])];
|
||||
DicConsole.DebugWriteLine("Reed Solomon", "\n ERROR: denominator = 0\n");
|
||||
return -1;
|
||||
}
|
||||
|
||||
return count;
|
||||
/* Apply error to data */
|
||||
if(num1 != 0) data[loc[j]] ^= alpha_to[Modnn(index_of[num1] + index_of[num2] + nn - index_of[den])];
|
||||
}
|
||||
|
||||
throw new UnauthorizedAccessException("Trying to calculate RS without initializing!");
|
||||
return count;
|
||||
}
|
||||
}
|
||||
}
|
||||
@@ -246,11 +246,10 @@ namespace DiscImageChef.Checksums
|
||||
* */
|
||||
self.Bh[i].Digest[++self.Bh[i].Dlen] = 0;
|
||||
self.Bh[i].H = HASH_INIT;
|
||||
if(self.Bh[i].Dlen < SPAMSUM_LENGTH / 2)
|
||||
{
|
||||
self.Bh[i].Halfh = HASH_INIT;
|
||||
self.Bh[i].Halfdigest = 0;
|
||||
}
|
||||
if(self.Bh[i].Dlen >= SPAMSUM_LENGTH / 2) continue;
|
||||
|
||||
self.Bh[i].Halfh = HASH_INIT;
|
||||
self.Bh[i].Halfdigest = 0;
|
||||
}
|
||||
else fuzzy_try_reduce_blockhash();
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user