[performance] Improve speed of our CRC-64 hasher

Modify the implementation to use splicing in order to process data in a
smaller number of iterations, at the expense of a bit more memory for
the extra tables.  A quick test of calculating checksum for a 1GB file
shows a ~5.5x improvement:

    Allocating 1043332542 bytes to hold file data
    Reading file 'android-ndk-r21-linux-x86_64.zip' into memory
    Calculating checksum using the old method... Hash: 197913BA13B9A1CC; Time: 00:00:04.0649818
    Calculating checksum using the new method... Hash: 8203D033719B6B96; Time: 00:00:00.7251845

The calculated hash is different (although still stable and correct)
because the new code uses tables generated using a slightly different
set of parameters.  Instead of using a single lookup table, the new
code takes the slice-by-8 approach (explained e.g. here https://create.stephan-brumme.com/crc32/#slicing-by-8-overview)
which processes 8 bytes at a time, using 8 lookup tables instead of one.

Author: grendello

src/Java.Interop.Tools.JavaCallableWrappers/Java.Interop.Tools.JavaCallableWrappers.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <PropertyGroup>

src/Java.Interop.Tools.JavaCallableWrappers/Java.Interop.Tools.JavaCallableWrappers/Crc64.Table.cs

@@ -35,144 +35,15 @@ namespace Java.Interop.Tools.JavaCallableWrappers
 {
 	/// <summary>
 	///  CRC64 variant: crc-64-jones 64-bit
-	///  * Poly: 0xad93d23594c935a9
+	///    * Poly: 0xad93d23594c935a9
+	///
 	///  Changes beyond initial implementation:
-	///  * Starting Value: ulong.MaxValue
-	///  * XOR length in HashFinal()
+	///    * Starting Value: ulong.MaxValue
+	///    * XOR length in HashFinal()
+	///    * Using spliced table for faster processing
 	/// </summary>
-	public class Crc64 : HashAlgorithm
+	public partial class Crc64 : HashAlgorithm
 	{
-		static readonly ulong [] Table = {
-		    0x0000000000000000, 0x7ad870c830358979,
-		    0xf5b0e190606b12f2, 0x8f689158505e9b8b,
-		    0xc038e5739841b68f, 0xbae095bba8743ff6,
-		    0x358804e3f82aa47d, 0x4f50742bc81f2d04,
-		    0xab28ecb46814fe75, 0xd1f09c7c5821770c,
-		    0x5e980d24087fec87, 0x24407dec384a65fe,
-		    0x6b1009c7f05548fa, 0x11c8790fc060c183,
-		    0x9ea0e857903e5a08, 0xe478989fa00bd371,
-		    0x7d08ff3b88be6f81, 0x07d08ff3b88be6f8,
-		    0x88b81eabe8d57d73, 0xf2606e63d8e0f40a,
-		    0xbd301a4810ffd90e, 0xc7e86a8020ca5077,
-		    0x4880fbd87094cbfc, 0x32588b1040a14285,
-		    0xd620138fe0aa91f4, 0xacf86347d09f188d,
-		    0x2390f21f80c18306, 0x594882d7b0f40a7f,
-		    0x1618f6fc78eb277b, 0x6cc0863448deae02,
-		    0xe3a8176c18803589, 0x997067a428b5bcf0,
-		    0xfa11fe77117cdf02, 0x80c98ebf2149567b,
-		    0x0fa11fe77117cdf0, 0x75796f2f41224489,
-		    0x3a291b04893d698d, 0x40f16bccb908e0f4,
-		    0xcf99fa94e9567b7f, 0xb5418a5cd963f206,
-		    0x513912c379682177, 0x2be1620b495da80e,
-		    0xa489f35319033385, 0xde51839b2936bafc,
-		    0x9101f7b0e12997f8, 0xebd98778d11c1e81,
-		    0x64b116208142850a, 0x1e6966e8b1770c73,
-		    0x8719014c99c2b083, 0xfdc17184a9f739fa,
-		    0x72a9e0dcf9a9a271, 0x08719014c99c2b08,
-		    0x4721e43f0183060c, 0x3df994f731b68f75,
-		    0xb29105af61e814fe, 0xc849756751dd9d87,
-		    0x2c31edf8f1d64ef6, 0x56e99d30c1e3c78f,
-		    0xd9810c6891bd5c04, 0xa3597ca0a188d57d,
-		    0xec09088b6997f879, 0x96d1784359a27100,
-		    0x19b9e91b09fcea8b, 0x636199d339c963f2,
-		    0xdf7adabd7a6e2d6f, 0xa5a2aa754a5ba416,
-		    0x2aca3b2d1a053f9d, 0x50124be52a30b6e4,
-		    0x1f423fcee22f9be0, 0x659a4f06d21a1299,
-		    0xeaf2de5e82448912, 0x902aae96b271006b,
-		    0x74523609127ad31a, 0x0e8a46c1224f5a63,
-		    0x81e2d7997211c1e8, 0xfb3aa75142244891,
-		    0xb46ad37a8a3b6595, 0xceb2a3b2ba0eecec,
-		    0x41da32eaea507767, 0x3b024222da65fe1e,
-		    0xa2722586f2d042ee, 0xd8aa554ec2e5cb97,
-		    0x57c2c41692bb501c, 0x2d1ab4dea28ed965,
-		    0x624ac0f56a91f461, 0x1892b03d5aa47d18,
-		    0x97fa21650afae693, 0xed2251ad3acf6fea,
-		    0x095ac9329ac4bc9b, 0x7382b9faaaf135e2,
-		    0xfcea28a2faafae69, 0x8632586aca9a2710,
-		    0xc9622c4102850a14, 0xb3ba5c8932b0836d,
-		    0x3cd2cdd162ee18e6, 0x460abd1952db919f,
-		    0x256b24ca6b12f26d, 0x5fb354025b277b14,
-		    0xd0dbc55a0b79e09f, 0xaa03b5923b4c69e6,
-		    0xe553c1b9f35344e2, 0x9f8bb171c366cd9b,
-		    0x10e3202993385610, 0x6a3b50e1a30ddf69,
-		    0x8e43c87e03060c18, 0xf49bb8b633338561,
-		    0x7bf329ee636d1eea, 0x012b592653589793,
-		    0x4e7b2d0d9b47ba97, 0x34a35dc5ab7233ee,
-		    0xbbcbcc9dfb2ca865, 0xc113bc55cb19211c,
-		    0x5863dbf1e3ac9dec, 0x22bbab39d3991495,
-		    0xadd33a6183c78f1e, 0xd70b4aa9b3f20667,
-		    0x985b3e827bed2b63, 0xe2834e4a4bd8a21a,
-		    0x6debdf121b863991, 0x1733afda2bb3b0e8,
-		    0xf34b37458bb86399, 0x8993478dbb8deae0,
-		    0x06fbd6d5ebd3716b, 0x7c23a61ddbe6f812,
-		    0x3373d23613f9d516, 0x49aba2fe23cc5c6f,
-		    0xc6c333a67392c7e4, 0xbc1b436e43a74e9d,
-		    0x95ac9329ac4bc9b5, 0xef74e3e19c7e40cc,
-		    0x601c72b9cc20db47, 0x1ac40271fc15523e,
-		    0x5594765a340a7f3a, 0x2f4c0692043ff643,
-		    0xa02497ca54616dc8, 0xdafce7026454e4b1,
-		    0x3e847f9dc45f37c0, 0x445c0f55f46abeb9,
-		    0xcb349e0da4342532, 0xb1eceec59401ac4b,
-		    0xfebc9aee5c1e814f, 0x8464ea266c2b0836,
-		    0x0b0c7b7e3c7593bd, 0x71d40bb60c401ac4,
-		    0xe8a46c1224f5a634, 0x927c1cda14c02f4d,
-		    0x1d148d82449eb4c6, 0x67ccfd4a74ab3dbf,
-		    0x289c8961bcb410bb, 0x5244f9a98c8199c2,
-		    0xdd2c68f1dcdf0249, 0xa7f41839ecea8b30,
-		    0x438c80a64ce15841, 0x3954f06e7cd4d138,
-		    0xb63c61362c8a4ab3, 0xcce411fe1cbfc3ca,
-		    0x83b465d5d4a0eece, 0xf96c151de49567b7,
-		    0x76048445b4cbfc3c, 0x0cdcf48d84fe7545,
-		    0x6fbd6d5ebd3716b7, 0x15651d968d029fce,
-		    0x9a0d8ccedd5c0445, 0xe0d5fc06ed698d3c,
-		    0xaf85882d2576a038, 0xd55df8e515432941,
-		    0x5a3569bd451db2ca, 0x20ed197575283bb3,
-		    0xc49581ead523e8c2, 0xbe4df122e51661bb,
-		    0x3125607ab548fa30, 0x4bfd10b2857d7349,
-		    0x04ad64994d625e4d, 0x7e7514517d57d734,
-		    0xf11d85092d094cbf, 0x8bc5f5c11d3cc5c6,
-		    0x12b5926535897936, 0x686de2ad05bcf04f,
-		    0xe70573f555e26bc4, 0x9ddd033d65d7e2bd,
-		    0xd28d7716adc8cfb9, 0xa85507de9dfd46c0,
-		    0x273d9686cda3dd4b, 0x5de5e64efd965432,
-		    0xb99d7ed15d9d8743, 0xc3450e196da80e3a,
-		    0x4c2d9f413df695b1, 0x36f5ef890dc31cc8,
-		    0x79a59ba2c5dc31cc, 0x037deb6af5e9b8b5,
-		    0x8c157a32a5b7233e, 0xf6cd0afa9582aa47,
-		    0x4ad64994d625e4da, 0x300e395ce6106da3,
-		    0xbf66a804b64ef628, 0xc5bed8cc867b7f51,
-		    0x8aeeace74e645255, 0xf036dc2f7e51db2c,
-		    0x7f5e4d772e0f40a7, 0x05863dbf1e3ac9de,
-		    0xe1fea520be311aaf, 0x9b26d5e88e0493d6,
-		    0x144e44b0de5a085d, 0x6e963478ee6f8124,
-		    0x21c640532670ac20, 0x5b1e309b16452559,
-		    0xd476a1c3461bbed2, 0xaeaed10b762e37ab,
-		    0x37deb6af5e9b8b5b, 0x4d06c6676eae0222,
-		    0xc26e573f3ef099a9, 0xb8b627f70ec510d0,
-		    0xf7e653dcc6da3dd4, 0x8d3e2314f6efb4ad,
-		    0x0256b24ca6b12f26, 0x788ec2849684a65f,
-		    0x9cf65a1b368f752e, 0xe62e2ad306bafc57,
-		    0x6946bb8b56e467dc, 0x139ecb4366d1eea5,
-		    0x5ccebf68aecec3a1, 0x2616cfa09efb4ad8,
-		    0xa97e5ef8cea5d153, 0xd3a62e30fe90582a,
-		    0xb0c7b7e3c7593bd8, 0xca1fc72bf76cb2a1,
-		    0x45775673a732292a, 0x3faf26bb9707a053,
-		    0x70ff52905f188d57, 0x0a2722586f2d042e,
-		    0x854fb3003f739fa5, 0xff97c3c80f4616dc,
-		    0x1bef5b57af4dc5ad, 0x61372b9f9f784cd4,
-		    0xee5fbac7cf26d75f, 0x9487ca0fff135e26,
-		    0xdbd7be24370c7322, 0xa10fceec0739fa5b,
-		    0x2e675fb4576761d0, 0x54bf2f7c6752e8a9,
-		    0xcdcf48d84fe75459, 0xb71738107fd2dd20,
-		    0x387fa9482f8c46ab, 0x42a7d9801fb9cfd2,
-		    0x0df7adabd7a6e2d6, 0x772fdd63e7936baf,
-		    0xf8474c3bb7cdf024, 0x829f3cf387f8795d,
-		    0x66e7a46c27f3aa2c, 0x1c3fd4a417c62355,
-		    0x935745fc4798b8de, 0xe98f353477ad31a7,
-		    0xa6df411fbfb21ca3, 0xdc0731d78f8795da,
-		    0x536fa08fdfd90e51, 0x29b7d047efec8728,
-		};
-
 		ulong crc = ulong.MaxValue;
 		ulong length = 0;
 
@@ -182,11 +53,36 @@ public override void Initialize ()
 			length = 0;
 		}
 
-		protected override void HashCore (byte [] array, int ibStart, int cbSize)
+		unsafe protected override void HashCore (byte [] array, int ibStart, int cbSize)
 		{
-			for (int i = ibStart; i < cbSize; i++) {
-				crc = Table [(byte) (crc ^ array [i])] ^ (crc >> 8);
+			int len = cbSize;
+			int idx = ibStart;
+
+			fixed (ulong* tptr = Table) {
+				fixed (byte* aptr = array) {
+					while (len >= 8) {
+						crc ^= (ulong)aptr[idx];
+						crc =
+							tptr [7 * 256 + (crc & 0xff)] ^
+							tptr [6 * 256 + ((crc >> 8) & 0xff)] ^
+							tptr [5 * 256 + ((crc >> 16) & 0xff)] ^
+							tptr [4 * 256 + ((crc >> 24) & 0xff)] ^
+							tptr [3 * 256 + ((crc >> 32) & 0xff)] ^
+							tptr [2 * 256 + ((crc >> 40) & 0xff)] ^
+							tptr [1 * 256 + ((crc >> 48) & 0xff)] ^
+							tptr [0 * 256 + (crc >> 56)];
+						idx += 8;
+						len -= 8;
+					}
+
+					while (len > 0) {
+						crc = tptr [0 * 256 + ((crc ^ aptr[idx]) & 0xff)] ^ (crc >> 8);
+						idx++;
+						len--;
+					}
+				}
 			}
+
 			length += (ulong) cbSize;
 		}
 

src/Java.Interop.Tools.JavaCallableWrappers/Java.Interop.Tools.JavaCallableWrappers/Crc64.cs

@@ -34,7 +34,7 @@ public void Hello ()
 		public void XmlDocument ()
 		{
 			var actual = ToHash ("System.Xml.XmlDocument, System.Xml");
-			Assert.AreEqual ("348bbd9fecf1b865", actual);
+			Assert.AreEqual ("b9c1bdfc7cd47543", actual);
 		}
 
 		[Test]

tests/Java.Interop.Tools.JavaCallableWrappers-Tests/Java.Interop.Tools.JavaCallableWrappers/Crc64Tests.cs

@@ -124,7 +124,7 @@ public void GenerateIndirectApplication (
 		)
 		{
 			var actual      = Generate (typeof (IndirectApplication), applicationJavaClass);
-			var expected    = @"package crc64197ae30a36756915;
+			var expected    = @"package crc64b57424eba1fa9d27;
 
 
 public class IndirectApplication
@@ -175,7 +175,7 @@ public void monodroidClearReferences ()
 		public void GenerateExportedMembers ()
 		{
 			var actual = Generate (typeof (ExportsMembers));
-			var expected = @"package crc64197ae30a36756915;
+			var expected = @"package crc64b57424eba1fa9d27;
 
 
 public class ExportsMembers
@@ -187,7 +187,7 @@ extends java.lang.Object
 	public static final String __md_methods;
 	static {
 		__md_methods = 
-			""n_GetInstance:()Lcrc64197ae30a36756915/ExportsMembers;:__export__\n"" +
+			""n_GetInstance:()Lcrc64b57424eba1fa9d27/ExportsMembers;:__export__\n"" +
 			""n_GetValue:()Ljava/lang/String;:__export__\n"" +
 			""n_methodNamesNotMangled:()V:__export__\n"" +
 			""n_CompletelyDifferentName:(Ljava/lang/String;I)Ljava/lang/String;:__export__\n"" +
@@ -198,17 +198,17 @@ extends java.lang.Object
 	}
 
 
-	public static crc64197ae30a36756915.ExportsMembers STATIC_INSTANCE = GetInstance ();
+	public static crc64b57424eba1fa9d27.ExportsMembers STATIC_INSTANCE = GetInstance ();
 
 
 	public java.lang.String VALUE = GetValue ();
 
-	public static crc64197ae30a36756915.ExportsMembers GetInstance ()
+	public static crc64b57424eba1fa9d27.ExportsMembers GetInstance ()
 	{
 		return n_GetInstance ();
 	}
 
-	private static native crc64197ae30a36756915.ExportsMembers n_GetInstance ();
+	private static native crc64b57424eba1fa9d27.ExportsMembers n_GetInstance ();
 
 	public java.lang.String GetValue ()
 	{
@@ -271,7 +271,7 @@ public void monodroidClearReferences ()
 		public void GenerateInnerClass ()
 		{
 			var actual = Generate (typeof (ExampleOuterClass));
-			var expected = @"package crc64197ae30a36756915;
+			var expected = @"package crc64b57424eba1fa9d27;
 
 
 public class ExampleOuterClass

tests/Java.Interop.Tools.JavaCallableWrappers-Tests/Java.Interop.Tools.JavaCallableWrappers/JavaCallableWrapperGeneratorTests.cs

@@ -29,7 +29,7 @@ public void TearDown ()
 		public void Crc64 ()
 		{
 			JavaNativeTypeManager.PackageNamingPolicy = PackageNamingPolicy.LowercaseCrc64;
-			Assert.AreEqual ("crc64b74743e9328eed0a", JavaNativeTypeManager.GetPackageName (typeof (string)));
+			Assert.AreEqual ("crc6479bf423bcb581100", JavaNativeTypeManager.GetPackageName (typeof (string)));
 		}
 
 		[Test]