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Code cleanup.

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This commit is contained in:
Natalia Portillo
2018-06-22 08:08:38 +01:00
parent d3f24ddefd
commit 7ba01b5076
13 changed files with 116 additions and 94 deletions
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57
ReedSolomon.cs
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@@ -289,11 +289,14 @@ namespace DiscImageChef.Checksums
* (@**(B0+i-1) + x) * (@**(B0+i-1) + x)
*/ */
for(int j = i - 1; j > 0; j--) for(int j = i - 1; j > 0; j--)
if(gg[j] != 0) gg[j] = gg[j - 1] ^ alpha_to[Modnn(index_of[gg[j]] + B0 + i - 1)]; if(gg[j] != 0)
else gg[j] = gg[j - 1]; gg[j] = gg[j - 1] ^ alpha_to[Modnn(index_of[gg[j]] + B0 + i - 1)];
else
gg[j] = gg[j - 1];
/* Gg[0] can never be zero */ /* Gg[0] can never be zero */
gg[0] = alpha_to[Modnn(index_of[gg[0]] + B0 + i - 1)]; gg[0] = alpha_to[Modnn(index_of[gg[0]] + B0 + i - 1)];
} }
/* convert Gg[] to index form for quicker encoding */ /* convert Gg[] to index form for quicker encoding */
for(i = 0; i <= nn - kk; i++) gg[i] = index_of[gg[i]]; for(i = 0; i <= nn - kk; i++) gg[i] = index_of[gg[i]];
} }
@@ -322,15 +325,19 @@ namespace DiscImageChef.Checksums
Clear(ref bb, nn - kk); Clear(ref bb, nn - kk);
for(i = kk - 1; i >= 0; i--) for(i = kk - 1; i >= 0; i--)
{ {
if(mm != 8) if(data[i] > nn) return -1; /* Illegal symbol */ if(mm != 8)
if(data[i] > nn)
return -1; /* Illegal symbol */
int feedback = index_of[data[i] ^ bb[nn - kk - 1]]; int feedback = index_of[data[i] ^ bb[nn - kk - 1]];
if(feedback != a0) if(feedback != a0)
{ {
/* feedback term is non-zero */ /* feedback term is non-zero */
for(int j = nn - kk - 1; j > 0; j--) for(int j = nn - kk - 1; j > 0; j--)
if(gg[j] != a0) bb[j] = bb[j - 1] ^ alpha_to[Modnn(gg[j] + feedback)]; if(gg[j] != a0)
else bb[j] = bb[j - 1]; 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)]; bb[0] = alpha_to[Modnn(gg[0] + feedback)];
} }
@@ -388,10 +395,13 @@ namespace DiscImageChef.Checksums
/* data[] is in polynomial form, copy and convert to index form */ /* data[] is in polynomial form, copy and convert to index form */
for(i = nn - 1; i >= 0; i--) for(i = nn - 1; i >= 0; i--)
{ {
if(mm != 8) if(data[i] > nn) return -1; /* Illegal symbol */ if(mm != 8)
if(data[i] > nn)
return -1; /* Illegal symbol */
recd[i] = index_of[data[i]]; recd[i] = index_of[data[i]];
} }
/* first form the syndromes; i.e., evaluate recd(x) at roots of g(x) /* first form the syndromes; i.e., evaluate recd(x) at roots of g(x)
* namely @**(B0+i), i = 0, ... ,(NN-KK-1) * namely @**(B0+i), i = 0, ... ,(NN-KK-1)
*/ */
@@ -400,7 +410,8 @@ namespace DiscImageChef.Checksums
{ {
tmp = 0; tmp = 0;
for(j = 0; j < nn; j++) 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)]; 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 */ * error */
@@ -426,7 +437,7 @@ namespace DiscImageChef.Checksums
} }
} }
#if DEBUG #if DEBUG
/* find roots of the erasure location polynomial */ /* find roots of the erasure location polynomial */
for(i = 1; i <= noEras; i++) reg[i] = index_of[lambda[i]]; for(i = 1; i <= noEras; i++) reg[i] = index_of[lambda[i]];
@@ -442,6 +453,7 @@ namespace DiscImageChef.Checksums
} }
if(q != 0) continue; if(q != 0) continue;
/* store root and error location /* store root and error location
* number indices * number indices
*/ */
@@ -461,7 +473,7 @@ namespace DiscImageChef.Checksums
for(i = 0; i < count; i++) DicConsole.DebugWriteLine("Reed Solomon", "{0} ", loc[i]); for(i = 0; i < count; i++) DicConsole.DebugWriteLine("Reed Solomon", "{0} ", loc[i]);
DicConsole.DebugWriteLine("Reed Solomon", "\n"); DicConsole.DebugWriteLine("Reed Solomon", "\n");
#endif #endif
} }
for(i = 0; i < nn - kk + 1; i++) b[i] = index_of[lambda[i]]; for(i = 0; i < nn - kk + 1; i++) b[i] = index_of[lambda[i]];
@@ -478,7 +490,8 @@ namespace DiscImageChef.Checksums
/* Compute discrepancy at the r-th step in poly-form */ /* Compute discrepancy at the r-th step in poly-form */
int discrR = 0; int discrR = 0;
for(i = 0; i < r; i++) 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])]; 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 */ discrR = index_of[discrR]; /* Index form */
if(discrR == a0) if(discrR == a0)
@@ -492,8 +505,10 @@ namespace DiscImageChef.Checksums
/* 7 lines below: T(x) <-- lambda(x) - discr_r*x*b(x) */ /* 7 lines below: T(x) <-- lambda(x) - discr_r*x*b(x) */
t[0] = lambda[0]; t[0] = lambda[0];
for(i = 0; i < nn - kk; i++) for(i = 0; i < nn - kk; i++)
if(b[i] != a0) t[i + 1] = lambda[i + 1] ^ alpha_to[Modnn(discrR + b[i])]; if(b[i] != a0)
else t[i + 1] = lambda[i + 1]; 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) if(2 * el <= r + noEras - 1)
{ {
@@ -523,6 +538,7 @@ namespace DiscImageChef.Checksums
lambda[i] = index_of[lambda[i]]; lambda[i] = index_of[lambda[i]];
if(lambda[i] != a0) degLambda = i; if(lambda[i] != a0) degLambda = i;
} }
/* /*
* Find roots of the error+erasure locator polynomial. By Chien * Find roots of the error+erasure locator polynomial. By Chien
* Search * Search
@@ -542,20 +558,22 @@ namespace DiscImageChef.Checksums
} }
if(q != 0) continue; if(q != 0) continue;
/* store root (index-form) and error location number */ /* store root (index-form) and error location number */
root[count] = i; root[count] = i;
loc[count] = nn - i; loc[count] = nn - i;
count++; count++;
} }
#if DEBUG #if DEBUG
DicConsole.DebugWriteLine("Reed Solomon", "\n Final error positions:\t"); DicConsole.DebugWriteLine("Reed Solomon", "\n Final error positions:\t");
for(i = 0; i < count; i++) DicConsole.DebugWriteLine("Reed Solomon", "{0} ", loc[i]); for(i = 0; i < count; i++) DicConsole.DebugWriteLine("Reed Solomon", "{0} ", loc[i]);
DicConsole.DebugWriteLine("Reed Solomon", "\n"); DicConsole.DebugWriteLine("Reed Solomon", "\n");
#endif #endif
if(degLambda != count) return -1; if(degLambda != count) return -1;
/* /*
* Compute err+eras evaluator poly omega(x) = s(x)*lambda(x) (modulo * Compute err+eras evaluator poly omega(x) = s(x)*lambda(x) (modulo
* x**(NN-KK)). in index form. Also find deg(omega). * x**(NN-KK)). in index form. Also find deg(omega).
@@ -566,7 +584,8 @@ namespace DiscImageChef.Checksums
tmp = 0; tmp = 0;
j = degLambda < i ? degLambda : i; j = degLambda < i ? degLambda : i;
for(; j >= 0; j--) for(; j >= 0; j--)
if(s[i + 1 - j] != a0 && lambda[j] != a0) tmp ^= alpha_to[Modnn(s[i + 1 - j] + lambda[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; if(tmp != 0) degOmega = i;
omega[i] = index_of[tmp]; omega[i] = index_of[tmp];
@@ -581,20 +600,24 @@ namespace DiscImageChef.Checksums
for(j = count - 1; j >= 0; j--) for(j = count - 1; j >= 0; j--)
{ {
int num1 = 0; int num1 = 0;
for(i = degOmega; i >= 0; i--) if(omega[i] != a0) num1 ^= alpha_to[Modnn(omega[i] + i * root[j])]; for(i = degOmega; i >= 0; i--)
if(omega[i] != a0)
num1 ^= alpha_to[Modnn(omega[i] + i * root[j])];
int num2 = alpha_to[Modnn(root[j] * (B0 - 1) + nn)]; int num2 = alpha_to[Modnn(root[j] * (B0 - 1) + nn)];
int den = 0; int den = 0;
/* lambda[i+1] for i even is the formal derivative lambda_pr of lambda[i] */ /* 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) 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(lambda[i + 1] != a0)
den ^= alpha_to[Modnn(lambda[i + 1] + i * root[j])];
if(den == 0) if(den == 0)
{ {
DicConsole.DebugWriteLine("Reed Solomon", "\n ERROR: denominator = 0\n"); DicConsole.DebugWriteLine("Reed Solomon", "\n ERROR: denominator = 0\n");
return -1; return -1;
} }
/* Apply error to data */ /* Apply error to data */
if(num1 != 0) data[loc[j]] ^= alpha_to[Modnn(index_of[num1] + index_of[num2] + nn - index_of[den])]; if(num1 != 0) data[loc[j]] ^= alpha_to[Modnn(index_of[num1] + index_of[num2] + nn - index_of[den])];
} }

3
SpamSumContext.cs
View File

@@ -72,8 +72,7 @@ namespace DiscImageChef.Checksums
/// </summary> /// </summary>
public SpamSumContext() public SpamSumContext()
{ {
self = self = new FuzzyState {Bh = new BlockhashContext[NUM_BLOCKHASHES]};
new FuzzyState {Bh = new BlockhashContext[NUM_BLOCKHASHES]};
for(int i = 0; i < NUM_BLOCKHASHES; i++) self.Bh[i].Digest = new byte[SPAMSUM_LENGTH]; for(int i = 0; i < NUM_BLOCKHASHES; i++) self.Bh[i].Digest = new byte[SPAMSUM_LENGTH];
self.Bhstart = 0; self.Bhstart = 0;