WIP: CompressSave 1.2.0

2025-12-10 09:23:28 +08:00 · 2022-11-20 16:36:02 +08:00
parent f4457c5fd2
commit aec98cda34
33 changed files with 714 additions and 334 deletions
--- a/CompressSave/Wrapper/DecompressionStream.cs
+++ b/CompressSave/Wrapper/DecompressionStream.cs
@@ -0,0 +1,148 @@
+using System;
+using System.IO;
+
+namespace CompressSave.Wrapper;
+
+public class DecompressionStream : Stream
+{
+    public WrapperDefines wrapper;
+
+    public override bool CanRead => true;
+
+    public override bool CanSeek => false;
+
+    public override bool CanWrite => false;
+
+    public override long Length => inStream.Length;
+
+    public override long Position 
+    {   get => readPos; 
+        set
+        {
+            if (value < readPos)
+                ResetStream();
+            else
+                value -= readPos;
+            byte[] tmpBuffer = new byte[1024];
+            while (value > 0)
+            {
+                value -= Read(tmpBuffer, 0, (int)(value < 1024 ? value : 1024));
+            }
+        } 
+    }
+
+    public Stream inStream;
+
+    IntPtr dctx = IntPtr.Zero;
+
+    readonly ByteSpan srcBuffer;
+    readonly ByteSpan dcmpBuffer;
+    private bool decompressFinish = false;
+    readonly long startPos = 0;
+    long readPos = 0; //sum of readlen
+
+    public DecompressionStream(WrapperDefines wrap, Stream inStream,int extraBufferSize = 512*1024)
+    {
+        this.wrapper = wrap;
+        this.inStream = inStream;
+        startPos = inStream.Position;
+        srcBuffer = new ByteSpan(new byte[extraBufferSize]);
+        int len = Fill();
+        long expect = wrapper.DecompressBegin(ref dctx, srcBuffer.Buffer, ref len, out var blockSize);
+        srcBuffer.Position += len;
+        if (expect < 0) throw new Exception(expect.ToString());
+        dcmpBuffer = new ByteSpan(new byte[blockSize]);
+    }
+
+    public void ResetStream()
+    {
+        inStream.Seek(startPos, SeekOrigin.Begin);
+        decompressFinish = false;
+        srcBuffer.Clear();
+        dcmpBuffer.Clear();
+        wrapper.DecompressContextReset(dctx);
+        readPos = 0;
+    }
+
+    public int Fill()
+    {
+        int suplus = srcBuffer.Length - srcBuffer.Position;
+        if (srcBuffer.Length> 0 && srcBuffer.Position >= suplus)
+        {
+            Array.Copy(srcBuffer, srcBuffer.Position, srcBuffer, 0, suplus);
+            srcBuffer.Length -= srcBuffer.Position;
+            srcBuffer.Position = 0;
+        }
+        if (srcBuffer.IdleCapacity > 0)
+        {
+            var readlen = inStream.Read(srcBuffer, srcBuffer.Length, srcBuffer.IdleCapacity);
+            srcBuffer.Length += readlen;
+        }
+        return srcBuffer.Length - srcBuffer.Position;
+    }
+
+    public override void Flush()
+    {
+            
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        wrapper.DecompressEnd(dctx);
+        dctx = IntPtr.Zero;
+        base.Dispose(disposing);
+    }
+
+    public override int Read(byte[] buffer, int offset, int count)
+    {
+        int readlen = 0;
+        while (count > (readlen += dcmpBuffer.Read(buffer, offset + readlen, count - readlen)) && !decompressFinish)
+        {
+            var buffSize = Fill();
+            if (buffSize <= 0) return readlen;
+
+            var rt = wrapper.DecompressUpdateEx(dctx, dcmpBuffer, 0, dcmpBuffer.Capacity, srcBuffer, srcBuffer.Position,buffSize);
+            if (rt.Expect < 0) throw new Exception(rt.Expect.ToString());
+            if (rt.Expect == 0) decompressFinish = true;
+
+            srcBuffer.Position += (int)rt.ReadLen;
+            dcmpBuffer.Position = 0;
+            dcmpBuffer.Length = (int)rt.WriteLen;
+        }
+        readPos += readlen;
+        return readlen;
+    }
+
+    public int PeekByte()
+    {
+        if (dcmpBuffer.Length <= dcmpBuffer.Position)
+        {
+            var buffSize = Fill();
+            if (buffSize <= 0) return -1;
+
+            var rt = wrapper.DecompressUpdateEx(dctx, dcmpBuffer, 0, dcmpBuffer.Capacity, srcBuffer, srcBuffer.Position, buffSize);
+            if (rt.Expect < 0) throw new Exception(rt.Expect.ToString());
+            if (rt.Expect == 0) decompressFinish = true;
+
+            srcBuffer.Position += (int)rt.ReadLen;
+            dcmpBuffer.Position = 0;
+            dcmpBuffer.Length = (int)rt.WriteLen;
+        }
+        return dcmpBuffer.Buffer[dcmpBuffer.Position];
+    }
+
+    public override long Seek(long offset, SeekOrigin origin)
+    {
+        throw new NotImplementedException();
+    }
+
+    public override void SetLength(long value)
+    {
+        throw new NotImplementedException();
+    }
+
+    public override void Write(byte[] buffer, int offset, int count)
+    {
+        throw new NotImplementedException();
+    }
+}