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cleanup

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This commit is contained in:
Grigory Chudov
2013-03-26 21:58:59 -04:00
parent 76111a5c6e
commit b6132b894c
1 changed files with 15 additions and 12 deletions
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27
CUETools.Codecs/CRC/CRC16.cs
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@@ -25,27 +25,25 @@ namespace CUETools.Codecs
} }
const ushort polynomial = 0x8005; const ushort polynomial = 0x8005;
const ushort reversePolynomial = 0xa001; const ushort reversePolynomial = 0x4003;
const ushort reversePolynomial2 = 0x4003;
static unsafe Crc16() static unsafe Crc16()
{ {
int poly = (polynomial + (1 << GF2_DIM));
for (ushort i = 0; i < table.Length; i++) for (ushort i = 0; i < table.Length; i++)
{ {
int crc = i; int crc = i;
for (int j = 0; j < GF2_DIM; j++) for (int j = 0; j < GF2_DIM; j++)
{ {
if ((crc & (1U << (GF2_DIM - 1))) != 0) if ((crc & (1U << (GF2_DIM - 1))) != 0)
crc = ((crc << 1) ^ poly); crc = ((crc << 1) ^ polynomial);
else else
crc <<= 1; crc <<= 1;
} }
table[i] = (ushort)(crc & ((1 << GF2_DIM) - 1)); table[i] = (ushort)(crc & ((1 << GF2_DIM) - 1));
} }
combineTable[0, 0] = reversePolynomial; combineTable[0, 0] = Crc16.Reflect(polynomial);
substractTable[0, GF2_DIM - 1] = reversePolynomial2; substractTable[0, GF2_DIM - 1] = reversePolynomial;
for (int n = 1; n < GF2_DIM; n++) for (int n = 1; n < GF2_DIM; n++)
{ {
combineTable[0, n] = (ushort)(1 << (n - 1)); combineTable[0, n] = (ushort)(1 << (n - 1));
@@ -94,10 +92,15 @@ namespace CUETools.Codecs
square[n] = gf2_matrix_times(mat, mat[n]); square[n] = gf2_matrix_times(mat, mat[n]);
} }
public static ushort Reflect(ushort crc)
{
return (ushort)Crc32.Reflect(crc, 16);
}
public static unsafe ushort Combine(ushort crc1, ushort crc2, long len2) public static unsafe ushort Combine(ushort crc1, ushort crc2, long len2)
{ {
crc1 = (ushort)Crc32.Reflect(crc1, 16); crc1 = Crc16.Reflect(crc1);
crc2 = (ushort)Crc32.Reflect(crc2, 16); crc2 = Crc16.Reflect(crc2);
/* degenerate case */ /* degenerate case */
if (len2 == 0) if (len2 == 0)
@@ -123,14 +126,14 @@ namespace CUETools.Codecs
/* return combined crc */ /* return combined crc */
crc1 ^= crc2; crc1 ^= crc2;
crc1 = (ushort)Crc32.Reflect(crc1, 16); crc1 = Crc16.Reflect(crc1);
return crc1; return crc1;
} }
public static unsafe ushort Substract(ushort crc1, ushort crc2, long len2) public static unsafe ushort Substract(ushort crc1, ushort crc2, long len2)
{ {
crc1 = (ushort)Crc32.Reflect(crc1, 16); crc1 = Crc16.Reflect(crc1);
crc2 = (ushort)Crc32.Reflect(crc2, 16); crc2 = Crc16.Reflect(crc2);
/* degenerate case */ /* degenerate case */
if (len2 == 0) if (len2 == 0)
return crc1; return crc1;
@@ -154,7 +157,7 @@ namespace CUETools.Codecs
} }
/* return combined crc */ /* return combined crc */
crc1 = (ushort)Crc32.Reflect(crc1, 16); crc1 = Crc16.Reflect(crc1);
return crc1; return crc1;
} }
} }