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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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49
ReedSolomon.cs
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@@ -289,11 +289,14 @@ namespace DiscImageChef.Checksums
* (@**(B0+i-1) + x)
*/
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)];
else gg[j] = gg[j - 1];
if(gg[j] != 0)
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] = alpha_to[Modnn(index_of[gg[0]] + B0 + i - 1)];
}
/* convert Gg[] to index form for quicker encoding */
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);
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]];
if(feedback != a0)
{
/* feedback term is non-zero */
for(int 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];
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)];
}
@@ -388,10 +395,13 @@ namespace DiscImageChef.Checksums
/* 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 */
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)
* namely @**(B0+i), i = 0, ... ,(NN-KK-1)
*/
@@ -400,7 +410,8 @@ namespace DiscImageChef.Checksums
{
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)];
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 =>
* error */
@@ -442,6 +453,7 @@ namespace DiscImageChef.Checksums
}
if(q != 0) continue;
/* store root and error location
* number indices
*/
@@ -478,7 +490,8 @@ namespace DiscImageChef.Checksums
/* Compute discrepancy at the r-th step in poly-form */
int 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])];
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)
@@ -492,8 +505,10 @@ namespace DiscImageChef.Checksums
/* 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(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)
{
@@ -523,6 +538,7 @@ namespace DiscImageChef.Checksums
lambda[i] = index_of[lambda[i]];
if(lambda[i] != a0) degLambda = i;
}
/*
* Find roots of the error+erasure locator polynomial. By Chien
* Search
@@ -542,6 +558,7 @@ namespace DiscImageChef.Checksums
}
if(q != 0) continue;
/* store root (index-form) and error location number */
root[count] = i;
loc[count] = nn - i;
@@ -556,6 +573,7 @@ namespace DiscImageChef.Checksums
#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).
@@ -566,7 +584,8 @@ namespace DiscImageChef.Checksums
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(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];
@@ -581,20 +600,24 @@ namespace DiscImageChef.Checksums
for(j = count - 1; j >= 0; j--)
{
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 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(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])];
}

3
SpamSumContext.cs
View File

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