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https://github.com/claunia/cuetools.net.git
synced 2025-12-16 18:14:25 +00:00
Optimizing verification
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chudov
@@ -4,16 +4,16 @@ using System.Text;
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namespace CUETools.Codecs
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{
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public class Crc32
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public static class Crc32
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{
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public uint[] table = new uint[256];
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public static readonly uint[] table;
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public uint ComputeChecksum(uint crc, byte val)
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public static uint ComputeChecksum(uint crc, byte val)
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{
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return (crc >> 8) ^ table[(crc & 0xff) ^ val];
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}
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public unsafe uint ComputeChecksum(uint crc, byte* bytes, int count)
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public static unsafe uint ComputeChecksum(uint crc, byte* bytes, int count)
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{
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fixed (uint *t = table)
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for (int i = 0; i < count; i++)
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@@ -21,19 +21,19 @@ namespace CUETools.Codecs
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return crc;
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}
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public unsafe uint ComputeChecksum(uint crc, byte[] bytes, int pos, int count)
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public static unsafe uint ComputeChecksum(uint crc, byte[] bytes, int pos, int count)
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{
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fixed (byte* pbytes = &bytes[pos])
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return ComputeChecksum(crc, pbytes, count);
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}
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public uint ComputeChecksum(uint crc, uint s)
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public static uint ComputeChecksum(uint crc, uint s)
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{
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return ComputeChecksum(ComputeChecksum(ComputeChecksum(ComputeChecksum(
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crc, (byte)s), (byte)(s >> 8)), (byte)(s >> 16)), (byte)(s >> 24));
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}
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public unsafe uint ComputeChecksum(uint crc, int * samples, int count)
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public static unsafe uint ComputeChecksum(uint crc, int* samples, int count)
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{
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for (int i = 0; i < count; i++)
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{
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@@ -44,7 +44,7 @@ namespace CUETools.Codecs
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return crc;
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}
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uint Reflect(uint val, int ch)
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static uint Reflect(uint val, int ch)
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{
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uint value = 0;
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// Swap bit 0 for bit 7
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@@ -60,8 +60,66 @@ namespace CUETools.Codecs
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const uint ulPolynomial = 0x04c11db7;
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public Crc32()
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private static readonly uint[,] combineTable;
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private static readonly uint[,] substractTable;
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#if need_invert_binary_matrix
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static unsafe void invert_binary_matrix(uint* mat, uint* inv, int rows)
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{
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int cols, i, j;
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uint tmp;
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cols = rows;
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for (i = 0; i < rows; i++) inv[i] = (1U << i);
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/* First -- convert into upper triangular */
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for (i = 0; i < cols; i++)
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{
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/* Swap rows if we ave a zero i,i element. If we can't swap, then the
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matrix was not invertible */
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if ((mat[i] & (1 << i)) == 0)
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{
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for (j = i + 1; j < rows && (mat[j] & (1 << i)) == 0; j++) ;
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if (j == rows)
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throw new Exception("Matrix not invertible");
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tmp = mat[i]; mat[i] = mat[j]; mat[j] = tmp;
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tmp = inv[i]; inv[i] = inv[j]; inv[j] = tmp;
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}
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/* Now for each j>i, add A_ji*Ai to Aj */
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for (j = i + 1; j != rows; j++)
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{
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if ((mat[j] & (1 << i)) != 0)
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{
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mat[j] ^= mat[i];
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inv[j] ^= inv[i];
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}
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}
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}
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/* Now the matrix is upper triangular. Start at the top and multiply down */
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for (i = rows - 1; i >= 0; i--)
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{
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for (j = 0; j < i; j++)
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{
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if ((mat[j] & (1 << i)) != 0)
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{
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/* mat[j] ^= mat[i]; */
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inv[j] ^= inv[i];
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}
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}
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}
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}
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#endif
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static unsafe Crc32()
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{
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table = new uint[256];
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for (uint i = 0; i < table.Length; i++)
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{
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table[i] = Reflect(i, 8) << 24;
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@@ -69,11 +127,33 @@ namespace CUETools.Codecs
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table[i] = (table[i] << 1) ^ ((table[i] & (1U << 31)) == 0 ? 0 : ulPolynomial);
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table[i] = Reflect(table[i], 32);
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}
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combineTable = new uint[GF2_DIM, GF2_DIM];
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substractTable = new uint[GF2_DIM, GF2_DIM];
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combineTable[0, 0] = 0xedb88320; /* CRC-32 polynomial */
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substractTable[0, 31] = 0xdb710641;
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for (int n = 1; n < GF2_DIM; n++)
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{
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combineTable[0, n] = 1U << (n - 1);
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substractTable[0, n - 1] = 1U << n;
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}
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fixed (uint* ct = &combineTable[0, 0], st = &substractTable[0, 0])
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{
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//for (int i = 0; i < GF2_DIM; i++)
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// st[32 + i] = ct[i];
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//invert_binary_matrix(st + 32, st, GF2_DIM);
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for (int i = 1; i < GF2_DIM; i++)
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{
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gf2_matrix_square(ct + i * 32, ct + (i - 1) * 32);
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gf2_matrix_square(st + i * 32, st + (i - 1) * 32);
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}
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}
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}
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const int GF2_DIM = 32;
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//const int GF2_DIM2 = 67;
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private unsafe uint gf2_matrix_times(uint* mat, uint vec)
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private static unsafe uint gf2_matrix_times(uint* mat, uint vec)
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{
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return *(mat++) * (vec & 1) ^
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*(mat++) * ((vec >>= 1) & 1) ^
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@@ -110,63 +190,67 @@ namespace CUETools.Codecs
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}
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/* ========================================================================= */
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private unsafe void gf2_matrix_square(uint *square, uint *mat)
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private static unsafe void gf2_matrix_square(uint *square, uint *mat)
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{
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for (int n = 0; n < GF2_DIM; n++)
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square[n] = gf2_matrix_times(mat, mat[n]);
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}
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public unsafe uint Combine(uint crc1, uint crc2, long len2)
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public static unsafe uint Combine(uint crc1, uint crc2, long len2)
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{
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int n;
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uint row;
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uint* even = stackalloc uint[GF2_DIM]; /* even-power-of-two zeros operator */
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uint* odd = stackalloc uint[GF2_DIM]; /* odd-power-of-two zeros operator */
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/* degenerate case */
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if (len2 == 0)
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return crc1;
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if (crc1 == 0)
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return crc2;
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if (len2 < 0)
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throw new ArgumentException("crc.Combine length cannot be negative", "len2");
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/* put operator for one zero bit in odd */
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odd[0] = 0xedb88320; /* CRC-32 polynomial */
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row = 1;
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for (n = 1; n < GF2_DIM; n++) {
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odd[n] = row;
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row <<= 1;
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fixed (uint* ct = &combineTable[0, 0])
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{
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int n = 3;
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do
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{
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/* apply zeros operator for this bit of len2 */
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if ((len2 & 1) != 0)
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crc1 = gf2_matrix_times(ct + 32 * n, crc1);
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len2 >>= 1;
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n = (n + 1) & (GF2_DIM - 1);
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/* if no more bits set, then done */
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} while (len2 != 0);
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}
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/* put operator for two zero bits in even */
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gf2_matrix_square(even, odd);
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/* put operator for four zero bits in odd */
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gf2_matrix_square(odd, even);
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/* apply len2 zeros to crc1 (first square will put the operator for one
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zero byte, eight zero bits, in even) */
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do {
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/* apply zeros operator for this bit of len2 */
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gf2_matrix_square(even, odd);
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if ((len2 & 1) != 0)
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crc1 = gf2_matrix_times(even, crc1);
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len2 >>= 1;
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/* if no more bits set, then done */
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if (len2 == 0)
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break;
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/* another iteration of the loop with odd and even swapped */
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gf2_matrix_square(odd, even);
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if ((len2 & 1) != 0)
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crc1 = gf2_matrix_times(odd, crc1);
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len2 >>= 1;
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/* if no more bits set, then done */
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} while (len2 != 0);
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/* return combined crc */
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crc1 ^= crc2;
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return crc1;
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}
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public static unsafe uint Substract(uint crc1, uint crc2, long len2)
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{
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/* degenerate case */
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if (len2 == 0)
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return crc1;
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if (len2 < 0)
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throw new ArgumentException("crc.Combine length cannot be negative", "len2");
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crc1 ^= crc2;
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fixed (uint* st = &substractTable[0, 0])
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{
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int n = 3;
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do
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{
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/* apply zeros operator for this bit of len2 */
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if ((len2 & 1) != 0)
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crc1 = gf2_matrix_times(st + 32 * n, crc1);
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len2 >>= 1;
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n = (n + 1) & (GF2_DIM - 1);
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/* if no more bits set, then done */
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} while (len2 != 0);
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}
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/* return combined crc */
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return crc1;
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}
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}
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}
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