From f61126f5ebd51c1b907184e2e5f9d7d5268c387d Mon Sep 17 00:00:00 2001
From: rewjx <lol1youki@163.com>
Date: Sat, 5 Feb 2022 20:58:08 +0800
Subject: [PATCH] update_Astronauts

---
 ArcFormats/Astronauts/ArcGXP.cs | 63 ++++++++++++---------------------
 1 file changed, 23 insertions(+), 40 deletions(-)

diff --git a/ArcFormats/Astronauts/ArcGXP.cs b/ArcFormats/Astronauts/ArcGXP.cs
index ba125fe6..2464d4d5 100644
--- a/ArcFormats/Astronauts/ArcGXP.cs
+++ b/ArcFormats/Astronauts/ArcGXP.cs
@@ -41,7 +41,7 @@ namespace GameRes.Formats.Astronauts
         public override bool  IsHierarchic { get { return true; } }
         public override bool      CanWrite { get { return false; } }
 
-        private bool UseNameAsKey { get; set; }
+        private bool UseNameAsKey = false;
 
         static readonly byte[] KnownKey = {
             0x40, 0x21, 0x28, 0x38, 0xA6, 0x6E, 0x43, 0xA5, 0x40, 0x21, 0x28, 0x38, 0xA6, 0x43, 0xA5, 0x64,
@@ -51,36 +51,28 @@ namespace GameRes.Formats.Astronauts
         public override ArcFile TryOpen(ArcView file)
         {
             UseNameAsKey = false;
-            ArcFile arc = TryOpenOrg(file);
-            if(arc == null)
+            ArcFile arc = TryOpenGxpFile(file);
+            if(null == arc)
             {
-                //try use arc name as key
-                UseNameAsKey = true;
-                arc = TryOpenOrg(file);
+                UseNameAsKey = true;    //try use arc name as key
+                arc = TryOpenGxpFile(file);
             }
             return arc;
         }
 
-        public ArcFile TryOpenOrg (ArcView file)
+        private ArcFile TryOpenGxpFile (ArcView file)
         {
             int count = file.View.ReadInt32 (0x18);
             if (!IsSaneCount (count))
                 return null;
-            string arcName = Path.GetFileName(file.Name);
-            byte[] arcNameBytes = Encoding.ASCII.GetBytes(arcName);
+            string arcname = Path.GetFileName(file.Name);
+            byte[] arcname_bytes = Encoding.ASCII.GetBytes(arcname);
             long base_offset = file.View.ReadInt64 (0x28);
-            uint entry_key = 0;
-            if(UseNameAsKey)
+            uint entry_key = KnownKey[0] | (1u ^ KnownKey[1]) << 8 | (2u ^ KnownKey[2]) << 16 | (3u ^ KnownKey[3]) << 24;
+            if (UseNameAsKey)
             {
-                byte b1 = (byte)(KnownKey[0] ^ arcNameBytes[0]);
-                byte b2 = (byte)(1u ^ KnownKey[1] ^ arcNameBytes[1 % arcNameBytes.Length]);
-                byte b3 = (byte)(2u ^ KnownKey[2] ^ arcNameBytes[2 % arcNameBytes.Length]);
-                byte b4 = (byte)(3u ^ KnownKey[3] ^ arcNameBytes[3 % arcNameBytes.Length]);
-                entry_key = (uint)(b1 | b2 << 8 | b3 << 16 | b4 << 24);
-            }
-            else
-            {
-                entry_key = KnownKey[0] | (1u ^ KnownKey[1]) << 8 | (2u ^ KnownKey[2]) << 16 | (3u ^ KnownKey[3]) << 24;
+                uint arcname_key = (uint)(arcname_bytes[0] | (arcname_bytes[1 % arcname_bytes.Length]) << 8 | (arcname_bytes[2 % arcname_bytes.Length]) << 16 | (arcname_bytes[3 % arcname_bytes.Length]) << 24);
+                entry_key ^= arcname_key;
             }
             uint index_offset = 0x30;
             var entry_buffer = new byte[0x100];
@@ -95,14 +87,9 @@ namespace GameRes.Formats.Astronauts
                 if (entry_length != file.View.Read (index_offset, entry_buffer, 0, entry_length))
                     return null;
                 if (UseNameAsKey)
-                {
-                    Decrypt(entry_buffer, entry_length, arcNameBytes);
-                }
+                    Decrypt(entry_buffer, entry_length, arcname_bytes);
                 else
-                {
-                    Decrypt(entry_buffer, entry_length);
-                }
-
+                    Decrypt(entry_buffer, entry_length);
                 int name_length = LittleEndian.ToInt32 (entry_buffer, 0xC) * 2; // length in characters
                 if (name_length >= entry_length)
                     return null;
@@ -123,27 +110,23 @@ namespace GameRes.Formats.Astronauts
             var data = arc.File.View.ReadBytes (entry.Offset, entry.Size);
             if (UseNameAsKey)
             {
-                string name = Path.GetFileName(arc.File.Name);
-                byte[] nameBytes = Encoding.ASCII.GetBytes(name);
-                Decrypt(data, entry.Size, nameBytes);
+                string arcname = Path.GetFileName(arc.File.Name);
+                byte[] arcname_bytes = Encoding.ASCII.GetBytes(arcname);
+                Decrypt(data, entry.Size, arcname_bytes);
             }
             else
-            {
-                Decrypt(data, entry.Size);
-            }
+                Decrypt(data, entry.Size);
             return new BinMemoryStream (data, entry.Name);
         }
 
-        static void Decrypt (byte[] data, uint length, byte[] keyStrBytes=null)
+        static void Decrypt (byte[] data, uint length, byte[] key=null)
         {
             for (uint i = 0; i < length; ++i)
             {
-                byte xorK = (byte)(i ^ KnownKey[i % KnownKey.Length]);
-                if(keyStrBytes != null)
-                {
-                    xorK ^= keyStrBytes[i % keyStrBytes.Length];
-                }
-                data[i] ^= xorK;
+                byte xorkey = (byte)(i ^ KnownKey[i % KnownKey.Length]);
+                if(null != key)
+                    xorkey ^= key[i % key.Length];
+                data[i] ^= xorkey;
             }
         }
     }