From 0c53148a96413eec254a6b3ba49d52fb7f48e24f Mon Sep 17 00:00:00 2001
From: Ladislav Zezula <zezula@volny.cz>
Date: Wed, 7 Jun 2023 12:39:59 +0200
Subject: Decompression refactoring

---
 src/SCompression.cpp  | 23 ++++++++++++++++++-----
 src/SFileReadFile.cpp | 21 +++++++++------------
 src/StormLib.h        |  2 --
 3 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/src/SCompression.cpp b/src/SCompression.cpp
index b689063..d6d2e27 100644
--- a/src/SCompression.cpp
+++ b/src/SCompression.cpp
@@ -1038,11 +1038,6 @@ int WINAPI SCompDecompress(void * pvOutBuffer, int * pcbOutBuffer, void * pvInBu
     return SCompDecompressInternal(dcmp_table, _countof(dcmp_table), pvOutBuffer, pcbOutBuffer, pvInBuffer, cbInBuffer);
 }
 
-int WINAPI SCompDecompress_SC1B(void * pvOutBuffer, int * pcbOutBuffer, void * pvInBuffer, int cbInBuffer)
-{
-    return SCompDecompressInternal(dcmp_table_sc_beta, _countof(dcmp_table_sc_beta), pvOutBuffer, pcbOutBuffer, pvInBuffer, cbInBuffer);
-}
-
 int WINAPI SCompDecompress2(void * pvOutBuffer, int * pcbOutBuffer, void * pvInBuffer, int cbInBuffer)
 {
     DECOMPRESS pfnDecompress1 = NULL;
@@ -1157,6 +1152,24 @@ int WINAPI SCompDecompress2(void * pvOutBuffer, int * pcbOutBuffer, void * pvInB
     return nResult;
 }
 
+int WINAPI SCompDecompressX(TMPQArchive * ha, void * pvOutBuffer, int * pcbOutBuffer, void * pvInBuffer, int cbInBuffer)
+{
+    // MPQs version 2 use their own fixed list of compression flags.
+    if(ha->pHeader->wFormatVersion >= MPQ_FORMAT_VERSION_2)
+    {
+        return SCompDecompress2(pvOutBuffer, pcbOutBuffer, pvInBuffer, cbInBuffer);
+    }
+
+    // Starcraft BETA has specific decompression table.
+    if(ha->dwFlags & MPQ_FLAG_STARCRAFT_BETA)
+    {
+        return SCompDecompressInternal(dcmp_table_sc_beta, _countof(dcmp_table_sc_beta), pvOutBuffer, pcbOutBuffer, pvInBuffer, cbInBuffer);
+    }
+
+    // Default: Use the common MPQ v1 decompression routine
+    return SCompDecompressInternal(dcmp_table, _countof(dcmp_table), pvOutBuffer, pcbOutBuffer, pvInBuffer, cbInBuffer);
+}
+
 /*****************************************************************************/
 /*                                                                           */
 /*   File decompression for MPK archives                                     */
diff --git a/src/SFileReadFile.cpp b/src/SFileReadFile.cpp
index 39f794e..b0698c1 100644
--- a/src/SFileReadFile.cpp
+++ b/src/SFileReadFile.cpp
@@ -13,6 +13,11 @@
 #include "StormLib.h"
 #include "StormCommon.h"
 
+//-----------------------------------------------------------------------------
+// External references (not public functions)
+
+int WINAPI SCompDecompressX(TMPQArchive * ha, void * pvOutBuffer, int * pcbOutBuffer, void * pbInBuffer, int cbInBuffer);
+
 //-----------------------------------------------------------------------------
 // Local functions
 
@@ -171,18 +176,10 @@ static DWORD ReadMpqSectors(TMPQFile * hf, LPBYTE pbBuffer, DWORD dwByteOffset,
                         // Remember the last used compression
                         hf->dwCompression0 = pbInSector[0];
 
-                        // Decompress the data
-                        if(ha->pHeader->wFormatVersion >= MPQ_FORMAT_VERSION_2)
-                        {
-                            nResult = SCompDecompress2(pbOutSector, &cbOutSector, pbInSector, cbInSector);
-                        }
-                        else
-                        {
-                            if(ha->dwFlags & MPQ_FLAG_STARCRAFT_BETA)
-                                nResult = SCompDecompress_SC1B(pbOutSector, &cbOutSector, pbInSector, cbInSector);
-                            else
-                                nResult = SCompDecompress(pbOutSector, &cbOutSector, pbInSector, cbInSector);
-                        }
+                        // Decompress the data. We need to perform MPQ-specific decompression,
+                        // as multiple Blizzard games may have their own decompression tables
+                        // and even decompression methods.
+                        nResult = SCompDecompressX(ha, pbOutSector, &cbOutSector, pbInSector, cbInSector);
                     }
 
                     // Is the file compressed by PKWARE Data Compression Library ?
diff --git a/src/StormLib.h b/src/StormLib.h
index 5142868..94e9813 100644
--- a/src/StormLib.h
+++ b/src/StormLib.h
@@ -1122,8 +1122,6 @@ int    WINAPI SCompExplode    (void * pvOutBuffer, int * pcbOutBuffer, void * pv
 int    WINAPI SCompCompress   (void * pvOutBuffer, int * pcbOutBuffer, void * pvInBuffer, int cbInBuffer, unsigned uCompressionMask, int nCmpType, int nCmpLevel);
 int    WINAPI SCompDecompress (void * pvOutBuffer, int * pcbOutBuffer, void * pvInBuffer, int cbInBuffer);
 int    WINAPI SCompDecompress2(void * pvOutBuffer, int * pcbOutBuffer, void * pvInBuffer, int cbInBuffer);
-int    WINAPI SCompDecompress_SC1B(void * pvOutBuffer, int * pcbOutBuffer, void * pvInBuffer, int cbInBuffer);
-//int    WINAPI SCompDecompress_SCBW(void * pvOutBuffer, int * pcbOutBuffer, void * pvInBuffer, int cbInBuffer);
 
 //-----------------------------------------------------------------------------
 // Non-Windows support for SetLastError/GetLastError
-- 
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