From 18e7d1f849acb57a0fb7dc8af2fcfd3634784c6b Mon Sep 17 00:00:00 2001
From: morkt <muvluv.ru@gmail.com>
Date: Fri, 21 Aug 2015 02:21:31 +0400
Subject: [PATCH] slightly improved CMP1 decompression performance.

---
 ArcFormats/RiddleSoft/ImageGCP.cs | 101 +++++++++++-------------------
 1 file changed, 37 insertions(+), 64 deletions(-)

diff --git a/ArcFormats/RiddleSoft/ImageGCP.cs b/ArcFormats/RiddleSoft/ImageGCP.cs
index ec2b87f3..2298b5e3 100644
--- a/ArcFormats/RiddleSoft/ImageGCP.cs
+++ b/ArcFormats/RiddleSoft/ImageGCP.cs
@@ -45,7 +45,7 @@ namespace GameRes.Formats.Riddle
     public class GcpFormat : ImageFormat
     {
         public override string         Tag { get { return "GCP"; } }
-        public override string Description { get { return "Riddle Soft RGB image format"; } }
+        public override string Description { get { return "Riddle Soft compressed bitmap"; } }
         public override uint     Signature { get { return 0x31504d43u; } } // 'CMP1'
 
         public override void Write (Stream file, ImageData image)
@@ -62,24 +62,22 @@ namespace GameRes.Formats.Riddle
             int pack_size = LittleEndian.ToInt32 (header, 8);
             if (data_size < 54)
                 return null;
-            using (var reader = new Reader (stream, pack_size, 0x22)) // BMP header
+            var reader = new CmpReader (stream, pack_size, 0x22); // BMP header
+            reader.Unpack();
+            var bmp = reader.Data;
+            if (bmp[0] != 'B' || bmp[1] != 'M')
+                return null;
+            int width = LittleEndian.ToInt32 (bmp, 0x12);
+            int height = LittleEndian.ToInt32 (bmp, 0x16);
+            int bpp = LittleEndian.ToInt16 (bmp, 0x1c);
+            return new GcpMetaData
             {
-                reader.Unpack();
-                var bmp = reader.Data;
-                if (bmp[0] != 'B' || bmp[1] != 'M')
-                    return null;
-                int width = LittleEndian.ToInt32 (bmp, 0x12);
-                int height = LittleEndian.ToInt32 (bmp, 0x16);
-                int bpp = LittleEndian.ToInt16 (bmp, 0x1c);
-                return new GcpMetaData
-                {
-                    Width = (uint)width,
-                    Height = (uint)height,
-                    BPP = bpp,
-                    DataSize = data_size,
-                    PackedSize = pack_size,
-                };
-            }
+                Width = (uint)width,
+                Height = (uint)height,
+                BPP = bpp,
+                DataSize = data_size,
+                PackedSize = pack_size,
+            };
         }
 
         public override ImageData Read (Stream stream, ImageMetaData info)
@@ -89,22 +87,20 @@ namespace GameRes.Formats.Riddle
                 throw new ArgumentException ("GcpFormat.Read should be supplied with GcpMetaData", "info");
 
             stream.Position = 12;
-            using (var reader = new Reader (stream, meta.PackedSize, meta.DataSize))
+            var reader = new CmpReader (stream, meta.PackedSize, meta.DataSize);
+            reader.Unpack();
+            using (var bmp = new MemoryStream (reader.Data, false))
             {
-                reader.Unpack();
-                using (var bmp = new MemoryStream (reader.Data, false))
-                {
-                    var decoder = new BmpBitmapDecoder (bmp,
-                        BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
-                    BitmapSource frame = decoder.Frames[0];
-                    frame.Freeze();
-                    return new ImageData (frame, info);
-                }
+                var decoder = new BmpBitmapDecoder (bmp,
+                    BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
+                BitmapSource frame = decoder.Frames[0];
+                frame.Freeze();
+                return new ImageData (frame, info);
             }
         }
     }
 
-    internal class Reader : IDisposable
+    internal class CmpReader
     {
         Stream          m_input;
         byte[]          m_output;
@@ -113,7 +109,7 @@ namespace GameRes.Formats.Riddle
 
         public byte[] Data { get { return m_output; } }
 
-        public Reader (Stream file, int src_size, int dst_size)
+        public CmpReader (Stream file, int src_size, int dst_size)
         {
             m_input = file;
             m_output = new byte[dst_size];
@@ -129,7 +125,7 @@ namespace GameRes.Formats.Riddle
                 shift[i] = 0x20;
             while (dst < m_output.Length)
             {
-                int bit = GetNextBit();
+                int bit = GetBits (1);
                 if (-1 == bit)
                     break;
                 if (1 == bit)
@@ -164,46 +160,23 @@ namespace GameRes.Formats.Riddle
         }
 
         int m_bits = 0;
+        int m_cached_bits = 0;
 
-        int GetNextBit ()
+        int GetBits (int count)
         {
-            bool bit = 0 != (m_bits & 0x80);
-            m_bits <<= 1;
-            if (0 == (m_bits & 0xff))
+            while (m_cached_bits < count)
             {
                 if (m_src_count++ >= m_src_total)
                     return -1;
-                m_bits = m_input.ReadByte();
-                if (-1 == m_bits)
-                    throw new EndOfStreamException ("Invalid compressed stream");
-                bit = 0 != (m_bits & 0x80);
-                m_bits = (m_bits << 1) | 1;
-            }
-            return bit ? 1 : 0;
-        }
-
-        int GetBits (int count, int data = 0)
-        {
-            while (count > 0)
-            {
-                int bit = GetNextBit();
-                if (-1 == bit)
+                int b = m_input.ReadByte();
+                if (-1 == b)
                     return -1;
-                data = (data << 1) | bit;
-                --count;
+                m_bits = (m_bits << 8) | b;
+                m_cached_bits += 8;
             }
-            return data;
+            int mask = (1 << count) - 1;
+            m_cached_bits -= count;
+            return (m_bits >> m_cached_bits) & mask;
         }
-
-        #region IDisposable Members
-        public void Dispose ()
-        {
-            if (null != m_input)
-            {
-                m_input = null;
-            }
-            GC.SuppressFinalize (this);
-        }
-        #endregion
     }
 }