diff --git a/CDChecksums.cs b/CDChecksums.cs
index 0a5c118..6f959a9 100644
--- a/CDChecksums.cs
+++ b/CDChecksums.cs
@@ -124,73 +124,73 @@ namespace DiscImageChef.Checksums
{
EccInit();
- if(channel[0x000] == 0x00 && // sync (12 bytes)
- channel[0x001] == 0xFF && channel[0x002] == 0xFF && channel[0x003] == 0xFF && channel[0x004] == 0xFF &&
- channel[0x005] == 0xFF && channel[0x006] == 0xFF && channel[0x007] == 0xFF && channel[0x008] == 0xFF &&
- channel[0x009] == 0xFF && channel[0x00A] == 0xFF && channel[0x00B] == 0x00)
+ if(channel[0x000] != 0x00 || channel[0x001] != 0xFF || channel[0x002] != 0xFF || channel[0x003] != 0xFF ||
+ channel[0x004] != 0xFF || channel[0x005] != 0xFF || channel[0x006] != 0xFF || channel[0x007] != 0xFF ||
+ channel[0x008] != 0xFF || channel[0x009] != 0xFF || channel[0x00A] != 0xFF ||
+ channel[0x00B] != 0x00) return null;
+
+ DicConsole.DebugWriteLine("CD checksums", "Data sector, address {0:X2}:{1:X2}:{2:X2}", channel[0x00C],
+ channel[0x00D], channel[0x00E]);
+
+ if(channel[0x00F] == 0x00) // mode (1 byte)
{
- DicConsole.DebugWriteLine("CD checksums", "Data sector, address {0:X2}:{1:X2}:{2:X2}", channel[0x00C],
- channel[0x00D], channel[0x00E]);
-
- if(channel[0x00F] == 0x00) // mode (1 byte)
- {
- DicConsole.DebugWriteLine("CD checksums", "Mode 0 sector at address {0:X2}:{1:X2}:{2:X2}",
- channel[0x00C], channel[0x00D], channel[0x00E]);
- for(int i = 0x010; i < 0x930; i++)
- if(channel[i] != 0x00)
- {
- DicConsole.DebugWriteLine("CD checksums",
- "Mode 0 sector with error at address: {0:X2}:{1:X2}:{2:X2}",
- channel[0x00C], channel[0x00D], channel[0x00E]);
- return false;
- }
-
- return true;
- }
-
- if(channel[0x00F] == 0x01) // mode (1 byte)
- {
- DicConsole.DebugWriteLine("CD checksums", "Mode 1 sector at address {0:X2}:{1:X2}:{2:X2}",
- channel[0x00C], channel[0x00D], channel[0x00E]);
-
- if(channel[0x814] != 0x00 || // reserved (8 bytes)
- channel[0x815] != 0x00 || channel[0x816] != 0x00 || channel[0x817] != 0x00 ||
- channel[0x818] != 0x00 || channel[0x819] != 0x00 || channel[0x81A] != 0x00 ||
- channel[0x81B] != 0x00)
+ DicConsole.DebugWriteLine("CD checksums", "Mode 0 sector at address {0:X2}:{1:X2}:{2:X2}",
+ channel[0x00C], channel[0x00D], channel[0x00E]);
+ for(int i = 0x010; i < 0x930; i++)
+ if(channel[i] != 0x00)
{
DicConsole.DebugWriteLine("CD checksums",
- "Mode 1 sector with data in reserved bytes at address: {0:X2}:{1:X2}:{2:X2}",
+ "Mode 0 sector with error at address: {0:X2}:{1:X2}:{2:X2}",
channel[0x00C], channel[0x00D], channel[0x00E]);
return false;
}
- byte[] address = new byte[4];
- byte[] data = new byte[2060];
- byte[] data2 = new byte[2232];
- byte[] eccP = new byte[172];
- byte[] eccQ = new byte[104];
+ return true;
+ }
- Array.Copy(channel, 0x0C, address, 0, 4);
- Array.Copy(channel, 0x0C, data, 0, 2060);
- Array.Copy(channel, 0x0C, data2, 0, 2232);
- Array.Copy(channel, 0x81C, eccP, 0, 172);
- Array.Copy(channel, 0x8C8, eccQ, 0, 104);
+ if(channel[0x00F] == 0x01) // mode (1 byte)
+ {
+ DicConsole.DebugWriteLine("CD checksums", "Mode 1 sector at address {0:X2}:{1:X2}:{2:X2}",
+ channel[0x00C], channel[0x00D], channel[0x00E]);
- bool failedEccP = CheckEcc(address, data, 86, 24, 2, 86, eccP);
- bool failedEccQ = CheckEcc(address, data2, 52, 43, 86, 88, eccQ);
+ if(channel[0x814] != 0x00 || // reserved (8 bytes)
+ channel[0x815] != 0x00 || channel[0x816] != 0x00 || channel[0x817] != 0x00 ||
+ channel[0x818] != 0x00 || channel[0x819] != 0x00 || channel[0x81A] != 0x00 ||
+ channel[0x81B] != 0x00)
+ {
+ DicConsole.DebugWriteLine("CD checksums",
+ "Mode 1 sector with data in reserved bytes at address: {0:X2}:{1:X2}:{2:X2}",
+ channel[0x00C], channel[0x00D], channel[0x00E]);
+ return false;
+ }
- if(failedEccP)
- DicConsole.DebugWriteLine("CD checksums",
- "Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC P check",
- channel[0x00C], channel[0x00D], channel[0x00E]);
- if(failedEccQ)
- DicConsole.DebugWriteLine("CD checksums",
- "Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC Q check",
- channel[0x00C], channel[0x00D], channel[0x00E]);
+ byte[] address = new byte[4];
+ byte[] data = new byte[2060];
+ byte[] data2 = new byte[2232];
+ byte[] eccP = new byte[172];
+ byte[] eccQ = new byte[104];
- if(failedEccP || failedEccQ) return false;
+ Array.Copy(channel, 0x0C, address, 0, 4);
+ Array.Copy(channel, 0x0C, data, 0, 2060);
+ Array.Copy(channel, 0x0C, data2, 0, 2232);
+ Array.Copy(channel, 0x81C, eccP, 0, 172);
+ Array.Copy(channel, 0x8C8, eccQ, 0, 104);
- /* TODO: This is not working
+ bool failedEccP = CheckEcc(address, data, 86, 24, 2, 86, eccP);
+ bool failedEccQ = CheckEcc(address, data2, 52, 43, 86, 88, eccQ);
+
+ if(failedEccP)
+ DicConsole.DebugWriteLine("CD checksums",
+ "Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC P check",
+ channel[0x00C], channel[0x00D], channel[0x00E]);
+ if(failedEccQ)
+ DicConsole.DebugWriteLine("CD checksums",
+ "Mode 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC Q check",
+ channel[0x00C], channel[0x00D], channel[0x00E]);
+
+ if(failedEccP || failedEccQ) return false;
+
+ /* TODO: This is not working
byte[] SectorForCheck = new byte[0x810];
uint StoredEDC = BitConverter.ToUInt32(channel, 0x810);
byte[] CalculatedEDCBytes;
@@ -204,23 +204,23 @@ namespace DiscImageChef.Checksums
return false;
}*/
- return true;
- }
+ return true;
+ }
- if(channel[0x00F] == 0x02) // mode (1 byte)
+ 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]);
+
+ if((channel[0x012] & 0x20) == 0x20) // mode 2 form 2
{
- DicConsole.DebugWriteLine("CD checksums", "Mode 2 sector at address {0:X2}:{1:X2}:{2:X2}",
- channel[0x00C], channel[0x00D], channel[0x00E]);
+ if(channel[0x010] != channel[0x014] || channel[0x011] != channel[0x015] ||
+ channel[0x012] != channel[0x016] || channel[0x013] != channel[0x017])
+ DicConsole.DebugWriteLine("CD checksums",
+ "Subheader copies differ in mode 2 form 2 sector at address: {0:X2}:{1:X2}:{2:X2}",
+ channel[0x00C], channel[0x00D], channel[0x00E]);
- if((channel[0x012] & 0x20) == 0x20) // mode 2 form 2
- {
- if(channel[0x010] != channel[0x014] || channel[0x011] != channel[0x015] ||
- channel[0x012] != channel[0x016] || channel[0x013] != channel[0x017])
- DicConsole.DebugWriteLine("CD 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
+ /* TODO: This is not working
byte[] SectorForCheck = new byte[0x91C];
uint StoredEDC = BitConverter.ToUInt32(channel, 0x92C);
byte[] CalculatedEDCBytes;
@@ -233,45 +233,45 @@ namespace DiscImageChef.Checksums
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
- {
- if(channel[0x010] != channel[0x014] || channel[0x011] != channel[0x015] ||
- channel[0x012] != channel[0x016] || channel[0x013] != channel[0x017])
- DicConsole.DebugWriteLine("CD checksums",
- "Subheader copies differ in mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}",
- channel[0x00C], channel[0x00D], channel[0x00E]);
+ }
+ else
+ {
+ if(channel[0x010] != channel[0x014] || channel[0x011] != channel[0x015] ||
+ channel[0x012] != channel[0x016] || channel[0x013] != channel[0x017])
+ DicConsole.DebugWriteLine("CD checksums",
+ "Subheader copies differ in mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}",
+ channel[0x00C], channel[0x00D], channel[0x00E]);
- byte[] address = new byte[4];
- byte[] data = new byte[2060];
- byte[] data2 = new byte[2232];
- byte[] eccP = new byte[172];
- byte[] eccQ = new byte[104];
+ byte[] address = new byte[4];
+ byte[] data = new byte[2060];
+ byte[] data2 = new byte[2232];
+ byte[] eccP = new byte[172];
+ byte[] eccQ = new byte[104];
- address[0] = 0;
- address[1] = 0;
- address[2] = 0;
- address[3] = 0;
- Array.Copy(channel, 0x0C, data, 0, 2060);
- Array.Copy(channel, 0x0C, data2, 0, 2232);
- Array.Copy(channel, 0x80C, eccP, 0, 172);
- Array.Copy(channel, 0x8B8, eccQ, 0, 104);
+ address[0] = 0;
+ address[1] = 0;
+ address[2] = 0;
+ address[3] = 0;
+ Array.Copy(channel, 0x0C, data, 0, 2060);
+ Array.Copy(channel, 0x0C, data2, 0, 2232);
+ Array.Copy(channel, 0x80C, eccP, 0, 172);
+ Array.Copy(channel, 0x8B8, eccQ, 0, 104);
- bool failedEccP = CheckEcc(address, data, 86, 24, 2, 86, eccP);
- bool failedEccQ = CheckEcc(address, data2, 52, 43, 86, 88, eccQ);
+ bool failedEccP = CheckEcc(address, data, 86, 24, 2, 86, eccP);
+ bool failedEccQ = CheckEcc(address, data2, 52, 43, 86, 88, eccQ);
- if(failedEccP)
- DicConsole.DebugWriteLine("CD checksums",
- "Mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC P check",
- channel[0x00C], channel[0x00D], channel[0x00E]);
- 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]);
+ if(failedEccP)
+ DicConsole.DebugWriteLine("CD checksums",
+ "Mode 2 form 1 sector at address: {0:X2}:{1:X2}:{2:X2}, fails ECC P check",
+ channel[0x00C], channel[0x00D], channel[0x00E]);
+ 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]);
- if(failedEccP || failedEccQ) return false;
+ if(failedEccP || failedEccQ) return false;
- /* TODO: This is not working
+ /* TODO: This is not working
byte[] SectorForCheck = new byte[0x808];
uint StoredEDC = BitConverter.ToUInt32(channel, 0x818);
byte[] CalculatedEDCBytes;
@@ -284,17 +284,14 @@ namespace DiscImageChef.Checksums
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);
return false;
}*/
- }
-
- return true;
}
- DicConsole.DebugWriteLine("CD checksums",
- "Unknown mode {0} sector at address: {1:X2}:{2:X2}:{3:X2}",
- channel[0x00F], channel[0x00C], channel[0x00D], channel[0x00E]);
- return null;
+ return true;
}
+ DicConsole.DebugWriteLine("CD checksums",
+ "Unknown mode {0} sector at address: {1:X2}:{2:X2}:{3:X2}",
+ channel[0x00F], channel[0x00C], channel[0x00D], channel[0x00E]);
return null;
}
@@ -478,22 +475,20 @@ namespace DiscImageChef.Checksums
}
}
- if((cdTextPack4[0] & 0x80) == 0x80)
- {
- ushort cdTextPack4Crc = BigEndianBitConverter.ToUInt16(cdTextPack4, 16);
- byte[] cdTextPack4ForCrc = new byte[16];
- Array.Copy(cdTextPack4, 0, cdTextPack4ForCrc, 0, 16);
- ushort calculatedCdtp4Crc = CalculateCCITT_CRC16(cdTextPack4ForCrc);
- DicConsole.DebugWriteLine("CD checksums", "Cyclic CDTP4 0x{0:X4}, Calc CDTP4 0x{1:X4}", cdTextPack4Crc,
- calculatedCdtp4Crc);
+ if((cdTextPack4[0] & 0x80) != 0x80) return status;
- if(cdTextPack4Crc != calculatedCdtp4Crc && cdTextPack4Crc != 0)
- {
- DicConsole.DebugWriteLine("CD checksums", "CD-Text Pack 4 CRC 0x{0:X4}, expected 0x{1:X4}",
- cdTextPack4Crc, calculatedCdtp4Crc);
- status = false;
- }
- }
+ ushort cdTextPack4Crc = BigEndianBitConverter.ToUInt16(cdTextPack4, 16);
+ byte[] cdTextPack4ForCrc = new byte[16];
+ Array.Copy(cdTextPack4, 0, cdTextPack4ForCrc, 0, 16);
+ ushort calculatedCdtp4Crc = CalculateCCITT_CRC16(cdTextPack4ForCrc);
+ DicConsole.DebugWriteLine("CD checksums", "Cyclic CDTP4 0x{0:X4}, Calc CDTP4 0x{1:X4}", cdTextPack4Crc,
+ calculatedCdtp4Crc);
+
+ if(cdTextPack4Crc == calculatedCdtp4Crc || cdTextPack4Crc == 0) return status;
+
+ DicConsole.DebugWriteLine("CD checksums", "CD-Text Pack 4 CRC 0x{0:X4}, expected 0x{1:X4}",
+ cdTextPack4Crc, calculatedCdtp4Crc);
+ status = false;
return status;
}
diff --git a/ReedSolomon.cs b/ReedSolomon.cs
index 8eeda85..5dbdcd3 100644
--- a/ReedSolomon.cs
+++ b/ReedSolomon.cs
@@ -305,41 +305,38 @@ namespace DiscImageChef.Checksums
/// Outs parity symbols.
public int encode_rs(int[] data, out int[] bb)
{
- if(initialized)
+ if(!initialized) throw new UnauthorizedAccessException("Trying to calculate RS without initializing!");
+
+ int i, j;
+ int feedback;
+ bb = new int[nn - kk];
+
+ Clear(ref bb, nn - kk);
+ for(i = kk - 1; i >= 0; i--)
{
- int i, j;
- int feedback;
- bb = new int[nn - kk];
+ if(mm != 8) if(data[i] > nn) return -1; /* Illegal symbol */
- Clear(ref bb, nn - kk);
- for(i = kk - 1; i >= 0; i--)
+ feedback = index_of[data[i] ^ bb[nn - kk - 1]];
+ if(feedback != a0)
{
- if(mm != 8) if(data[i] > nn) return -1; /* Illegal symbol */
+ /* feedback term is non-zero */
+ for(j = nn - kk - 1; j > 0; j--)
+ if(gg[j] != a0) bb[j] = bb[j - 1] ^ alpha_to[Modnn(gg[j] + feedback)];
+ else bb[j] = bb[j - 1];
- feedback = index_of[data[i] ^ bb[nn - kk - 1]];
- if(feedback != a0)
- {
- /* feedback term is non-zero */
- for(j = nn - kk - 1; j > 0; j--)
- if(gg[j] != a0) bb[j] = bb[j - 1] ^ alpha_to[Modnn(gg[j] + feedback)];
- else bb[j] = bb[j - 1];
-
- bb[0] = alpha_to[Modnn(gg[0] + feedback)];
- }
- else
- {
- /* feedback term is zero. encoder becomes a
- * single-byte shifter */
- for(j = nn - kk - 1; j > 0; j--) bb[j] = bb[j - 1];
-
- bb[0] = 0;
- }
+ bb[0] = alpha_to[Modnn(gg[0] + feedback)];
}
+ else
+ {
+ /* feedback term is zero. encoder becomes a
+ * 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
/// Number of erasures.
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;
}
}
}
\ No newline at end of file
diff --git a/SpamSumContext.cs b/SpamSumContext.cs
index 8b18a6f..6e815e5 100644
--- a/SpamSumContext.cs
+++ b/SpamSumContext.cs
@@ -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();
}