mirror of
https://github.com/aaru-dps/Aaru.Checksums.git
synced 2025-12-16 19:24:29 +00:00
Use zlib-inspired algorithm for Adler and Fletcher checksums.
This commit is contained in:
@@ -43,6 +43,7 @@ namespace Aaru.Checksums
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public sealed class Fletcher32Context : IChecksum
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{
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const ushort FLETCHER_MODULE = 0xFFFF;
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const uint NMAX = 5552;
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ushort _sum1, _sum2;
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/// <summary>Initializes the Fletcher-32 sums</summary>
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@@ -56,14 +57,7 @@ namespace Aaru.Checksums
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/// <summary>Updates the hash with data.</summary>
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/// <param name="data">Data buffer.</param>
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/// <param name="len">Length of buffer to hash.</param>
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public void Update(byte[] data, uint len)
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{
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for(int i = 0; i < len; i++)
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{
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_sum1 = (ushort)((_sum1 + data[i]) % FLETCHER_MODULE);
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_sum2 = (ushort)((_sum2 + _sum1) % FLETCHER_MODULE);
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}
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}
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public void Update(byte[] data, uint len) => Step(ref _sum1, ref _sum2, data, len);
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/// <inheritdoc />
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/// <summary>Updates the hash with data.</summary>
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@@ -92,6 +86,157 @@ namespace Aaru.Checksums
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return fletcherOutput.ToString();
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}
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static void Step(ref ushort previousSum1, ref ushort previousSum2, byte[] data, uint len)
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{
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uint sum1 = previousSum1;
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uint sum2 = previousSum2;
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uint n;
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int dataOff = 0;
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/* in case user likes doing a byte at a time, keep it fast */
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if(len == 1)
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{
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sum1 += data[dataOff];
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if(sum1 >= FLETCHER_MODULE)
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sum1 -= FLETCHER_MODULE;
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sum2 += sum1;
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if(sum2 >= FLETCHER_MODULE)
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sum2 -= FLETCHER_MODULE;
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previousSum1 = (ushort)(sum1 & 0xFFFF);
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previousSum2 = (ushort)(sum2 & 0xFFFF);
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return;
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}
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/* in case short lengths are provided, keep it somewhat fast */
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if(len < 16)
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{
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while(len-- > 0)
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{
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sum1 += data[dataOff++];
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sum2 += sum1;
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}
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if(sum1 >= FLETCHER_MODULE)
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sum1 -= FLETCHER_MODULE;
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sum2 %= FLETCHER_MODULE; /* only added so many FLETCHER_MODULE's */
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previousSum1 = (ushort)(sum1 & 0xFFFF);
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previousSum2 = (ushort)(sum2 & 0xFFFF);
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return;
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}
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/* do length NMAX blocks -- requires just one modulo operation */
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while(len >= NMAX)
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{
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len -= NMAX;
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n = NMAX / 16; /* NMAX is divisible by 16 */
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do
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{
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sum1 += data[dataOff];
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sum2 += sum1;
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sum1 += data[dataOff + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 4];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 4];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 4 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 4 + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 4 + 2 + 1];
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sum2 += sum1;
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/* 16 sums unrolled */
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dataOff += 16;
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} while(--n != 0);
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sum1 %= FLETCHER_MODULE;
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sum2 %= FLETCHER_MODULE;
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}
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/* do remaining bytes (less than NMAX, still just one modulo) */
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if(len != 0)
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{
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/* avoid modulos if none remaining */
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while(len >= 16)
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{
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len -= 16;
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sum1 += data[dataOff];
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sum2 += sum1;
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sum1 += data[dataOff + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 4];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 4];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 4 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 4 + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 4 + 2 + 1];
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sum2 += sum1;
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dataOff += 16;
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}
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while(len-- != 0)
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{
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sum1 += data[dataOff++];
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sum2 += sum1;
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}
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sum1 %= FLETCHER_MODULE;
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sum2 %= FLETCHER_MODULE;
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}
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previousSum1 = (ushort)(sum1 & 0xFFFF);
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previousSum2 = (ushort)(sum2 & 0xFFFF);
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}
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/// <summary>Gets the hash of a file</summary>
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/// <param name="filename">File path.</param>
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public static byte[] File(string filename)
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@@ -111,10 +256,14 @@ namespace Aaru.Checksums
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ushort localSum1 = 0xFFFF;
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ushort localSum2 = 0xFFFF;
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for(int i = 0; i < fileStream.Length; i++)
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byte[] buffer = new byte[65536];
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int read = fileStream.Read(buffer, 0, 65536);
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while(read > 0)
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{
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localSum1 = (ushort)((localSum1 + fileStream.ReadByte()) % FLETCHER_MODULE);
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localSum2 = (ushort)((localSum2 + localSum1) % FLETCHER_MODULE);
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Step(ref localSum1, ref localSum2, buffer, (uint)read);
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read = fileStream.Read(buffer, 0, 65536);
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}
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uint finalSum = (uint)((localSum2 << 16) | localSum1);
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@@ -140,11 +289,7 @@ namespace Aaru.Checksums
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ushort localSum1 = 0xFFFF;
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ushort localSum2 = 0xFFFF;
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for(int i = 0; i < len; i++)
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{
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localSum1 = (ushort)((localSum1 + data[i]) % FLETCHER_MODULE);
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localSum2 = (ushort)((localSum2 + localSum1) % FLETCHER_MODULE);
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}
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Step(ref localSum1, ref localSum2, data, len);
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uint finalSum = (uint)((localSum2 << 16) | localSum1);
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@@ -169,6 +314,7 @@ namespace Aaru.Checksums
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public sealed class Fletcher16Context : IChecksum
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{
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const byte FLETCHER_MODULE = 0xFF;
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const byte NMAX = 22;
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byte _sum1, _sum2;
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/// <summary>Initializes the Fletcher-16 sums</summary>
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@@ -182,14 +328,7 @@ namespace Aaru.Checksums
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/// <summary>Updates the hash with data.</summary>
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/// <param name="data">Data buffer.</param>
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/// <param name="len">Length of buffer to hash.</param>
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public void Update(byte[] data, uint len)
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{
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for(int i = 0; i < len; i++)
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{
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_sum1 = (byte)((_sum1 + data[i]) % FLETCHER_MODULE);
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_sum2 = (byte)((_sum2 + _sum1) % FLETCHER_MODULE);
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}
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}
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public void Update(byte[] data, uint len) => Step(ref _sum1, ref _sum2, data, len);
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/// <inheritdoc />
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/// <summary>Updates the hash with data.</summary>
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@@ -218,6 +357,137 @@ namespace Aaru.Checksums
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return fletcherOutput.ToString();
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}
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static void Step(ref byte previousSum1, ref byte previousSum2, byte[] data, uint len)
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{
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uint sum1 = previousSum1;
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uint sum2 = previousSum2;
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uint n;
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int dataOff = 0;
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/* in case user likes doing a byte at a time, keep it fast */
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if(len == 1)
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{
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sum1 += data[dataOff];
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if(sum1 >= FLETCHER_MODULE)
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sum1 -= FLETCHER_MODULE;
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sum2 += sum1;
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if(sum2 >= FLETCHER_MODULE)
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sum2 -= FLETCHER_MODULE;
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previousSum1 = (byte)(sum1 & 0xFF);
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previousSum2 = (byte)(sum2 & 0xFF);
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return;
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}
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/* in case short lengths are provided, keep it somewhat fast */
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if(len < 11)
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{
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while(len-- > 0)
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{
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sum1 += data[dataOff++];
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sum2 += sum1;
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}
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if(sum1 >= FLETCHER_MODULE)
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sum1 -= FLETCHER_MODULE;
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sum2 %= FLETCHER_MODULE; /* only added so many FLETCHER_MODULE's */
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previousSum1 = (byte)(sum1 & 0xFF);
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previousSum2 = (byte)(sum2 & 0xFF);
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return;
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}
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/* do length NMAX blocks -- requires just one modulo operation */
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while(len >= NMAX)
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{
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len -= NMAX;
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n = NMAX / 11; /* NMAX is divisible by 16 */
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do
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{
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sum1 += data[dataOff];
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sum2 += sum1;
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sum1 += data[dataOff + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 4];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 2];
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sum2 += sum1;
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/* 11 sums unrolled */
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dataOff += 11;
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} while(--n != 0);
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sum1 %= FLETCHER_MODULE;
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sum2 %= FLETCHER_MODULE;
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}
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/* do remaining bytes (less than NMAX, still just one modulo) */
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if(len != 0)
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{
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/* avoid modulos if none remaining */
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while(len >= 11)
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{
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len -= 11;
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sum1 += data[dataOff];
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sum2 += sum1;
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sum1 += data[dataOff + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 4];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 2];
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sum2 += sum1;
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sum1 += data[dataOff + 4 + 2 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 1];
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sum2 += sum1;
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sum1 += data[dataOff + 8 + 2];
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sum2 += sum1;
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dataOff += 11;
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}
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while(len-- != 0)
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{
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sum1 += data[dataOff++];
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sum2 += sum1;
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}
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sum1 %= FLETCHER_MODULE;
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sum2 %= FLETCHER_MODULE;
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}
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previousSum1 = (byte)(sum1 & 0xFF);
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previousSum2 = (byte)(sum2 & 0xFF);
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}
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/// <summary>Gets the hash of a file</summary>
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/// <param name="filename">File path.</param>
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public static byte[] File(string filename)
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@@ -237,10 +507,14 @@ namespace Aaru.Checksums
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byte localSum1 = 0xFF;
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byte localSum2 = 0xFF;
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for(int i = 0; i < fileStream.Length; i++)
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byte[] buffer = new byte[65536];
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int read = fileStream.Read(buffer, 0, 65536);
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while(read > 0)
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{
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localSum1 = (byte)((localSum1 + fileStream.ReadByte()) % FLETCHER_MODULE);
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localSum2 = (byte)((localSum2 + localSum1) % FLETCHER_MODULE);
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Step(ref localSum1, ref localSum2, buffer, (uint)read);
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read = fileStream.Read(buffer, 0, 65536);
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}
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ushort finalSum = (ushort)((localSum2 << 8) | localSum1);
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@@ -266,11 +540,7 @@ namespace Aaru.Checksums
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byte localSum1 = 0xFF;
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byte localSum2 = 0xFF;
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for(int i = 0; i < len; i++)
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{
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localSum1 = (byte)((localSum1 + data[i]) % FLETCHER_MODULE);
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localSum2 = (byte)((localSum2 + localSum1) % FLETCHER_MODULE);
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}
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Step(ref localSum1, ref localSum2, data, len);
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ushort finalSum = (ushort)((localSum2 << 8) | localSum1);
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