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Naming fixes.

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This commit is contained in:
Natalia Portillo
2020-07-20 21:11:31 +01:00
parent 41d26c7057
commit 843291076c
12 changed files with 308 additions and 308 deletions
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276
ReedSolomon.cs
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@@ -68,20 +68,20 @@ namespace Aaru.Checksums
/// <summary>Alpha exponent for the first root of the generator polynomial</summary>
const int B0 = 1;
/// <summary>No legal value in index form represents zero, so we need a special value for this purpose</summary>
int a0;
int _a0;
/// <summary>index->polynomial form conversion table</summary>
int[] alpha_to;
int[] _alphaTo;
/// <summary>Generator polynomial g(x) Degree of g(x) = 2*TT has roots @**B0, @**(B0+1), ... ,@^(B0+2*TT-1)</summary>
int[] gg;
int[] _gg;
/// <summary>Polynomial->index form conversion table</summary>
int[] index_of;
bool initialized;
int mm, kk, nn;
int[] _indexOf;
bool _initialized;
int _mm, _kk, _nn;
/// <summary>
/// Primitive polynomials - see Lin & Costello, Error Control Coding Appendix A, and Lee & Messerschmitt, Digital
/// Communication p. 453.
/// </summary>
int[] pp;
int[] _pp;
/// <summary>Initializes the Reed-Solomon with RS(n,k) with GF(2^m)</summary>
public void InitRs(int n, int k, int m)
@@ -89,105 +89,105 @@ namespace Aaru.Checksums
switch(m)
{
case 2:
pp = new[]
_pp = new[]
{
1, 1, 1
};
break;
case 3:
pp = new[]
_pp = new[]
{
1, 1, 0, 1
};
break;
case 4:
pp = new[]
_pp = new[]
{
1, 1, 0, 0, 1
};
break;
case 5:
pp = new[]
_pp = new[]
{
1, 0, 1, 0, 0, 1
};
break;
case 6:
pp = new[]
_pp = new[]
{
1, 1, 0, 0, 0, 0, 1
};
break;
case 7:
pp = new[]
_pp = new[]
{
1, 0, 0, 1, 0, 0, 0, 1
};
break;
case 8:
pp = new[]
_pp = new[]
{
1, 0, 1, 1, 1, 0, 0, 0, 1
};
break;
case 9:
pp = new[]
_pp = new[]
{
1, 0, 0, 0, 1, 0, 0, 0, 0, 1
};
break;
case 10:
pp = new[]
_pp = new[]
{
1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1
};
break;
case 11:
pp = new[]
_pp = new[]
{
1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1
};
break;
case 12:
pp = new[]
_pp = new[]
{
1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1
};
break;
case 13:
pp = new[]
_pp = new[]
{
1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1
};
break;
case 14:
pp = new[]
_pp = new[]
{
1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1
};
break;
case 15:
pp = new[]
_pp = new[]
{
1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
};
break;
case 16:
pp = new[]
_pp = new[]
{
1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1
};
@@ -196,27 +196,27 @@ namespace Aaru.Checksums
default: throw new ArgumentOutOfRangeException(nameof(m), "m must be between 2 and 16 inclusive");
}
mm = m;
kk = k;
nn = n;
a0 = n;
alpha_to = new int[n + 1];
index_of = new int[n + 1];
_mm = m;
_kk = k;
_nn = n;
_a0 = n;
_alphaTo = new int[n + 1];
_indexOf = new int[n + 1];
gg = new int[(nn - kk) + 1];
_gg = new int[(_nn - _kk) + 1];
generate_gf();
gen_poly();
initialized = true;
_initialized = true;
}
int Modnn(int x)
{
while(x >= nn)
while(x >= _nn)
{
x -= nn;
x = (x >> mm) + (x & nn);
x -= _nn;
x = (x >> _mm) + (x & _nn);
}
return x;
@@ -283,21 +283,21 @@ namespace Aaru.Checksums
int i;
int mask = 1;
alpha_to[mm] = 0;
_alphaTo[_mm] = 0;
for(i = 0; i < mm; i++)
for(i = 0; i < _mm; i++)
{
alpha_to[i] = mask;
index_of[alpha_to[i]] = i;
_alphaTo[i] = mask;
_indexOf[_alphaTo[i]] = i;
/* If Pp[i] == 1 then, term @^i occurs in poly-repr of @^MM */
if(pp[i] != 0)
alpha_to[mm] ^= mask; /* Bit-wise EXOR operation */
if(_pp[i] != 0)
_alphaTo[_mm] ^= mask; /* Bit-wise EXOR operation */
mask <<= 1; /* single left-shift */
}
index_of[alpha_to[mm]] = mm;
_indexOf[_alphaTo[_mm]] = _mm;
/*
* Have obtained poly-repr of @^MM. Poly-repr of @^(i+1) is given by
* poly-repr of @^i shifted left one-bit and accounting for any @^MM
@@ -305,18 +305,18 @@ namespace Aaru.Checksums
*/
mask >>= 1;
for(i = mm + 1; i < nn; i++)
for(i = _mm + 1; i < _nn; i++)
{
if(alpha_to[i - 1] >= mask)
alpha_to[i] = alpha_to[mm] ^ ((alpha_to[i - 1] ^ mask) << 1);
if(_alphaTo[i - 1] >= mask)
_alphaTo[i] = _alphaTo[_mm] ^ ((_alphaTo[i - 1] ^ mask) << 1);
else
alpha_to[i] = alpha_to[i - 1] << 1;
_alphaTo[i] = _alphaTo[i - 1] << 1;
index_of[alpha_to[i]] = i;
_indexOf[_alphaTo[i]] = i;
}
index_of[0] = a0;
alpha_to[nn] = 0;
_indexOf[0] = _a0;
_alphaTo[_nn] = 0;
}
/*
@@ -336,30 +336,30 @@ namespace Aaru.Checksums
{
int i;
gg[0] = alpha_to[B0];
gg[1] = 1; /* g(x) = (X+@**B0) initially */
_gg[0] = _alphaTo[B0];
_gg[1] = 1; /* g(x) = (X+@**B0) initially */
for(i = 2; i <= nn - kk; i++)
for(i = 2; i <= _nn - _kk; i++)
{
gg[i] = 1;
_gg[i] = 1;
/*
* Below multiply (Gg[0]+Gg[1]*x + ... +Gg[i]x^i) by
* (@**(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)];
if(_gg[j] != 0)
_gg[j] = _gg[j - 1] ^ _alphaTo[Modnn((_indexOf[_gg[j]] + B0 + i) - 1)];
else
gg[j] = gg[j - 1];
_gg[j] = _gg[j - 1];
/* Gg[0] can never be zero */
gg[0] = alpha_to[Modnn((index_of[gg[0]] + B0 + i) - 1)];
_gg[0] = _alphaTo[Modnn((_indexOf[_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]];
for(i = 0; i <= _nn - _kk; i++)
_gg[i] = _indexOf[_gg[i]];
}
/*
@@ -376,38 +376,38 @@ namespace Aaru.Checksums
/// <param name="bb">Outs parity symbols.</param>
public int encode_rs(int[] data, out int[] bb)
{
if(!initialized)
if(!_initialized)
throw new UnauthorizedAccessException("Trying to calculate RS without initializing!");
int i;
bb = new int[nn - kk];
bb = new int[_nn - _kk];
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)
if(_mm != 8)
if(data[i] > _nn)
return -1; /* Illegal symbol */
int feedback = index_of[data[i] ^ bb[nn - kk - 1]];
int feedback = _indexOf[data[i] ^ bb[_nn - _kk - 1]];
if(feedback != a0)
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)];
for(int j = _nn - _kk - 1; j > 0; j--)
if(_gg[j] != _a0)
bb[j] = bb[j - 1] ^ _alphaTo[Modnn(_gg[j] + feedback)];
else
bb[j] = bb[j - 1];
bb[0] = alpha_to[Modnn(gg[0] + feedback)];
bb[0] = _alphaTo[Modnn(_gg[0] + feedback)];
}
else
{
/* feedback term is zero. encoder becomes a
* single-byte shifter */
for(int j = nn - kk - 1; j > 0; j--)
for(int j = _nn - _kk - 1; j > 0; j--)
bb[j] = bb[j - 1];
bb[0] = 0;
@@ -437,31 +437,31 @@ namespace Aaru.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];
erasPos = new int[_nn - _kk];
int i, j;
int q, tmp;
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[] 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 count;
/* 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)
if(_mm != 8)
if(data[i] > _nn)
return -1; /* Illegal symbol */
recd[i] = index_of[data[i]];
recd[i] = _indexOf[data[i]];
}
/* first form the syndromes; i.e., evaluate recd(x) at roots of g(x)
@@ -469,31 +469,31 @@ namespace Aaru.Checksums
*/
int synError = 0;
for(i = 1; i <= nn - kk; i++)
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))];
for(j = 0; j < _nn; j++)
if(recd[j] != _a0) /* recd[j] in index form */
tmp ^= _alphaTo[Modnn(recd[j] + (((B0 + i) - 1) * j))];
synError |= tmp; /* set flag if non-zero syndrome =>
* error */
/* store syndrome in index form */
s[i] = index_of[tmp];
s[i] = _indexOf[tmp];
}
if(synError == 0)
return 0;
Clear(ref lambda, nn - kk);
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]];
lambda[1] = _alphaTo[erasPos[0]];
for(i = 1; i < noEras; i++)
{
@@ -501,29 +501,29 @@ namespace Aaru.Checksums
for(j = i + 1; j > 0; j--)
{
tmp = index_of[lambda[j - 1]];
tmp = _indexOf[lambda[j - 1]];
if(tmp != a0)
lambda[j] ^= alpha_to[Modnn(u + tmp)];
if(tmp != _a0)
lambda[j] ^= _alphaTo[Modnn(u + tmp)];
}
}
#if DEBUG
/* find roots of the erasure location polynomial */
for(i = 1; i <= noEras; i++)
reg[i] = index_of[lambda[i]];
reg[i] = _indexOf[lambda[i]];
count = 0;
for(i = 1; i <= nn; i++)
for(i = 1; i <= _nn; i++)
{
q = 1;
for(j = 1; j <= noEras; j++)
if(reg[j] != a0)
if(reg[j] != _a0)
{
reg[j] = Modnn(reg[j] + j);
q ^= alpha_to[reg[j]];
q ^= _alphaTo[reg[j]];
}
if(q != 0)
@@ -533,7 +533,7 @@ namespace Aaru.Checksums
* number indices
*/
root[count] = i;
loc[count] = nn - i;
loc[count] = _nn - i;
count++;
}
@@ -554,8 +554,8 @@ namespace Aaru.Checksums
#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] = _indexOf[lambda[i]];
/*
* Begin Berlekamp-Massey algorithm to determine error+erasure
@@ -564,7 +564,7 @@ namespace Aaru.Checksums
int r = noEras;
int el = noEras;
while(++r <= nn - kk)
while(++r <= _nn - _kk)
{
/* r is the step number */
/* Compute discrepancy at the r-th step in poly-form */
@@ -572,25 +572,25 @@ namespace Aaru.Checksums
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])];
s[r - i] != _a0)
discrR ^= _alphaTo[Modnn(_indexOf[lambda[i]] + s[r - i])];
discrR = index_of[discrR]; /* Index form */
discrR = _indexOf[discrR]; /* Index form */
if(discrR == a0)
if(discrR == _a0)
{
/* 2 lines below: B(x) <-- x*B(x) */
Copydown(ref b, ref b, nn - kk);
b[0] = a0;
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])];
for(i = 0; i < _nn - _kk; i++)
if(b[i] != _a0)
t[i + 1] = lambda[i + 1] ^ _alphaTo[Modnn(discrR + b[i])];
else
t[i + 1] = lambda[i + 1];
@@ -602,28 +602,28 @@ namespace Aaru.Checksums
* 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);
for(i = 0; i <= _nn - _kk; i++)
b[i] = lambda[i] == 0 ? _a0 : Modnn((_indexOf[lambda[i]] - discrR) + _nn);
}
else
{
/* 2 lines below: B(x) <-- x*B(x) */
Copydown(ref b, ref b, nn - kk);
b[0] = a0;
Copydown(ref b, ref b, _nn - _kk);
b[0] = _a0;
}
Copy(ref lambda, ref t, (nn - kk) + 1);
Copy(ref lambda, ref t, (_nn - _kk) + 1);
}
}
/* Convert lambda to index form and compute deg(lambda(x)) */
int degLambda = 0;
for(i = 0; i < (nn - kk) + 1; i++)
for(i = 0; i < (_nn - _kk) + 1; i++)
{
lambda[i] = index_of[lambda[i]];
lambda[i] = _indexOf[lambda[i]];
if(lambda[i] != a0)
if(lambda[i] != _a0)
degLambda = i;
}
@@ -632,19 +632,19 @@ namespace Aaru.Checksums
* Search
*/
int temp = reg[0];
Copy(ref reg, ref lambda, nn - kk);
Copy(ref reg, ref lambda, _nn - _kk);
reg[0] = temp;
count = 0; /* Number of roots of lambda(x) */
for(i = 1; i <= nn; i++)
for(i = 1; i <= _nn; i++)
{
q = 1;
for(j = degLambda; j > 0; j--)
if(reg[j] != a0)
if(reg[j] != _a0)
{
reg[j] = Modnn(reg[j] + j);
q ^= alpha_to[reg[j]];
q ^= _alphaTo[reg[j]];
}
if(q != 0)
@@ -652,7 +652,7 @@ namespace Aaru.Checksums
/* store root (index-form) and error location number */
root[count] = i;
loc[count] = nn - i;
loc[count] = _nn - i;
count++;
}
@@ -674,23 +674,23 @@ namespace Aaru.Checksums
*/
int degOmega = 0;
for(i = 0; i < nn - kk; i++)
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(s[(i + 1) - j] != _a0 &&
lambda[j] != _a0)
tmp ^= _alphaTo[Modnn(s[(i + 1) - j] + lambda[j])];
if(tmp != 0)
degOmega = i;
omega[i] = index_of[tmp];
omega[i] = _indexOf[tmp];
}
omega[nn - kk] = a0;
omega[_nn - _kk] = _a0;
/*
* Compute error values in poly-form. num1 = omega(inv(X(l))), num2 =
@@ -701,16 +701,16 @@ namespace Aaru.Checksums
int num1 = 0;
for(i = degOmega; i >= 0; i--)
if(omega[i] != a0)
num1 ^= alpha_to[Modnn(omega[i] + (i * root[j]))];
if(omega[i] != _a0)
num1 ^= _alphaTo[Modnn(omega[i] + (i * root[j]))];
int num2 = alpha_to[Modnn((root[j] * (B0 - 1)) + nn)];
int num2 = _alphaTo[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]))];
for(i = Min(degLambda, _nn - _kk - 1) & ~1; i >= 0; i -= 2)
if(lambda[i + 1] != _a0)
den ^= _alphaTo[Modnn(lambda[i + 1] + (i * root[j]))];
if(den == 0)
{
@@ -721,7 +721,7 @@ namespace Aaru.Checksums
/* Apply error to data */
if(num1 != 0)
data[loc[j]] ^= alpha_to[Modnn((index_of[num1] + index_of[num2] + nn) - index_of[den])];
data[loc[j]] ^= _alphaTo[Modnn((_indexOf[num1] + _indexOf[num2] + _nn) - _indexOf[den])];
}
return count;