From 00579927e43bf55ee06ae02933c1e755fb4120eb Mon Sep 17 00:00:00 2001
From: gdkchan <gab.dark.100@gmail.com>
Date: Wed, 28 Nov 2018 20:18:09 -0200
Subject: Better process implementation (#491)

* Initial implementation of KProcess

* Some improvements to the memory manager, implement back guest stack trace printing

* Better GetInfo implementation, improve checking in some places with information from process capabilities

* Allow the cpu to read/write from the correct memory locations for accesses crossing a page boundary

* Change long -> ulong for address/size on memory related methods to avoid unnecessary casts

* Attempt at implementing ldr:ro with new KProcess

* Allow BSS with size 0 on ldr:ro

* Add checking for memory block slab heap usage, return errors if full, exit gracefully

* Use KMemoryBlockSize const from KMemoryManager

* Allow all methods to read from non-contiguous locations

* Fix for TransactParcelAuto

* Address PR feedback, additionally fix some small issues related to the KIP loader and implement SVCs GetProcessId, GetProcessList, GetSystemInfo, CreatePort and ManageNamedPort

* Fix wrong check for source pages count from page list on MapPhysicalMemory

* Fix some issues with UnloadNro on ldr:ro
---
 Ryujinx.HLE/Loaders/Compression/BackwardsLz.cs | 105 +++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 Ryujinx.HLE/Loaders/Compression/BackwardsLz.cs

(limited to 'Ryujinx.HLE/Loaders/Compression')

diff --git a/Ryujinx.HLE/Loaders/Compression/BackwardsLz.cs b/Ryujinx.HLE/Loaders/Compression/BackwardsLz.cs
new file mode 100644
index 00000000..43cc601f
--- /dev/null
+++ b/Ryujinx.HLE/Loaders/Compression/BackwardsLz.cs
@@ -0,0 +1,105 @@
+using System;
+using System.IO;
+
+namespace Ryujinx.HLE.Loaders.Compression
+{
+    static class BackwardsLz
+    {
+        private class BackwardsReader
+        {
+            private Stream BaseStream;
+
+            public BackwardsReader(Stream BaseStream)
+            {
+                this.BaseStream = BaseStream;
+            }
+
+            public byte ReadByte()
+            {
+                BaseStream.Seek(-1, SeekOrigin.Current);
+
+                byte Value = (byte)BaseStream.ReadByte();
+
+                BaseStream.Seek(-1, SeekOrigin.Current);
+
+                return Value;
+            }
+
+            public short ReadInt16()
+            {
+                return (short)((ReadByte() << 8) | (ReadByte() << 0));
+            }
+
+            public int ReadInt32()
+            {
+                return ((ReadByte() << 24) |
+                        (ReadByte() << 16) |
+                        (ReadByte() << 8)  |
+                        (ReadByte() << 0));
+            }
+        }
+
+        public static byte[] Decompress(Stream Input, int DecompressedLength)
+        {
+            long End = Input.Position;
+
+            BackwardsReader Reader = new BackwardsReader(Input);
+
+            int AdditionalDecLength = Reader.ReadInt32();
+            int StartOffset         = Reader.ReadInt32();
+            int CompressedLength    = Reader.ReadInt32();
+
+            Input.Seek(12 - StartOffset, SeekOrigin.Current);
+
+            byte[] Dec = new byte[DecompressedLength];
+
+            int DecompressedLengthUnpadded = CompressedLength + AdditionalDecLength;
+
+            int DecompressionStart = DecompressedLength - DecompressedLengthUnpadded;
+
+            int DecPos = Dec.Length;
+
+            byte Mask   = 0;
+            byte Header = 0;
+
+            while (DecPos > DecompressionStart)
+            {
+                if ((Mask >>= 1) == 0)
+                {
+                    Header = Reader.ReadByte();
+                    Mask   = 0x80;
+                }
+
+                if ((Header & Mask) == 0)
+                {
+                    Dec[--DecPos] = Reader.ReadByte();
+                }
+                else
+                {
+                    ushort Pair = (ushort)Reader.ReadInt16();
+
+                    int Length   = (Pair >> 12)   + 3;
+                    int Position = (Pair & 0xfff) + 3;
+
+                    DecPos -= Length;
+
+                    if (Length <= Position)
+                    {
+                        int SrcPos = DecPos + Position;
+
+                        Buffer.BlockCopy(Dec, SrcPos, Dec, DecPos, Length);
+                    }
+                    else
+                    {
+                        for (int Offset = 0; Offset < Length; Offset++)
+                        {
+                            Dec[DecPos + Offset] = Dec[DecPos + Position + Offset];
+                        }
+                    }
+                }
+            }
+
+            return Dec;
+        }
+    }
+}
\ No newline at end of file
-- 
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