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source/src/Microsoft.Cuckoo/SimpleStreamSerializer.cs

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+// -----------------------------------------------------------------------
+// <copyright file="SimpleStreamSerializer.cs" company="Microsoft">
+//     Copyright (c) Microsoft. All rights reserved.
+// </copyright>
+// -----------------------------------------------------------------------
+
+using System.IO;
+
+namespace Microsoft.Cuckoo;
+
+/// <summary>
+///     Simple stream serializer that writes the cuckoo filter directly out
+///     to a stream. Investigate <see cref="GzipStreamSerializer" /> for a more
+///     storage-friendly version.
+/// </summary>
+public class SimpleStreamSerializer : ICuckooSerializer
+{
+    /// <summary>
+    ///     Deserializes the CuckooFilter to from a stream.
+    /// </summary>
+    /// <param name="source">Source stream to read</param>
+    /// <param name="hashAlgorithm">Hash algorithm</param>
+    public virtual CuckooFilter Deserialize(Stream source, IHashAlgorithm hashAlgorithm = null)
+    {
+        var paramsReadBuffer = new byte[16];
+        //source.Read(paramsReadBuffer, 0, 16);
+        source.ReadExactly(paramsReadBuffer);
+
+        var entriesPerBucket = ReadBigEndianUint(paramsReadBuffer, 0);
+        var fingerprintLength = ReadBigEndianUint(paramsReadBuffer, 4);
+        var buckets = ReadBigEndianUint(paramsReadBuffer, 8);
+        var maxKicks = ReadBigEndianUint(paramsReadBuffer, 12);
+
+        var contents = new byte[buckets * entriesPerBucket * fingerprintLength];
+        //source.Read(contents, 0, contents.Length);
+        source.ReadExactly(contents);
+
+        return new CuckooFilter(
+            contents,
+            entriesPerBucket,
+            fingerprintLength,
+            maxKicks,
+            hashAlgorithm);
+    }
+
+    /// <summary>
+    ///     Serializes the CuckooFilter to a stream.
+    /// </summary>
+    /// <param name="target">Target stream to write to</param>
+    /// <param name="filter">Filter to serialize</param>
+    public virtual void Serialize(Stream target, CuckooFilter filter)
+    {
+        var writeBuffer = new byte[16];
+        WriteBigEndianUint(writeBuffer, filter.EntriesPerBucket, 0);
+        WriteBigEndianUint(writeBuffer, filter.FingerprintLength, 4);
+        WriteBigEndianUint(writeBuffer, filter.Buckets, 8);
+        WriteBigEndianUint(writeBuffer, filter.MaxKicks, 12);
+        target.Write(writeBuffer, 0, 16);
+        target.Write(filter.Contents, 0, filter.Contents.Length);
+    }
+
+    private static uint ReadBigEndianUint(byte[] target, int offset)
+    {
+        uint x = 0;
+        x |= (uint)(target[offset] << 24);
+        x |= (uint)(target[offset + 1] << 16);
+        x |= (uint)(target[offset + 2] << 8);
+        x |= target[offset + 3];
+
+        return x;
+    }
+
+    private static void WriteBigEndianUint(byte[] target, uint number, int offset)
+    {
+        target[offset] = (byte)(number >> 24);
+        target[offset + 1] = (byte)(number >> 16);
+        target[offset + 2] = (byte)(number >> 8);
+        target[offset + 3] = (byte)number;
+    }
+}