Support loading Zstandard-compressed ROMs (#1667)

This is different from the archive support in that the compressed ROMs
are standalone files, rather than archives, making it possible to use
them exactly as if they were regular ROMs, while saving a bunch of space
on disk. This is supported both for DS and GBA ROMs, though given GBA
ROMs' generally small size it's mostly useful for the former.

3 files changed, 107 insertions, 16 deletions

diff --git a/src/frontend/qt_sdl/CMakeLists.txt b/src/frontend/qt_sdl/CMakeLists.txt
index 0387c58..00e4c03 100644
--- a/src/frontend/qt_sdl/CMakeLists.txt
+++ b/src/frontend/qt_sdl/CMakeLists.txt
@@ -82,6 +82,7 @@ endif()
 pkg_check_modules(SDL2 REQUIRED IMPORTED_TARGET sdl2)
 pkg_check_modules(Slirp REQUIRED IMPORTED_TARGET slirp)
 pkg_check_modules(LibArchive REQUIRED IMPORTED_TARGET libarchive)
+pkg_check_modules(Zstd REQUIRED IMPORTED_TARGET libzstd)
 
 fix_interface_includes(PkgConfig::SDL2 PkgConfig::Slirp PkgConfig::LibArchive)
 
@@ -154,7 +155,7 @@ else()
     target_include_directories(melonDS PUBLIC ${Qt5Gui_PRIVATE_INCLUDE_DIRS})
 endif()
 target_link_libraries(melonDS PRIVATE core)
-target_link_libraries(melonDS PRIVATE PkgConfig::SDL2 PkgConfig::Slirp PkgConfig::LibArchive)
+target_link_libraries(melonDS PRIVATE PkgConfig::SDL2 PkgConfig::Slirp PkgConfig::LibArchive PkgConfig::Zstd)
 target_link_libraries(melonDS PRIVATE ${QT_LINK_LIBS} ${CMAKE_DL_LIBS})
 
 if (UNIX)
diff --git a/src/frontend/qt_sdl/ROMManager.cpp b/src/frontend/qt_sdl/ROMManager.cpp
index cb671e2..95337e1 100644
--- a/src/frontend/qt_sdl/ROMManager.cpp
+++ b/src/frontend/qt_sdl/ROMManager.cpp
@@ -22,6 +22,7 @@
 #include <string>
 #include <utility>
 
+#include <zstd.h>
 #ifdef ARCHIVE_SUPPORT_ENABLED
 #include "ArchiveUtil.h"
 #endif
@@ -491,6 +492,27 @@ bool LoadBIOS()
     return true;
 }
 
+u32 DecompressROM(const u8* inContent, const u32 inSize, u8** outContent)
+{
+    u64 realSize = ZSTD_getFrameContentSize(inContent, inSize);
+
+    if (realSize == ZSTD_CONTENTSIZE_UNKNOWN || realSize == ZSTD_CONTENTSIZE_ERROR || realSize > 0x40000000)
+    {
+        return 0;
+    }
+
+    u8* realContent = new u8[realSize];
+    u64 decompressed = ZSTD_decompress(realContent, realSize, inContent, inSize);
+
+    if (ZSTD_isError(decompressed))
+    {
+        delete[] realContent;
+        return 0;
+    }
+
+    *outContent = realContent;
+    return realSize;
+}
 
 bool LoadROM(QStringList filepath, bool reset)
 {
@@ -533,6 +555,25 @@ bool LoadROM(QStringList filepath, bool reset)
         fclose(f);
         filelen = (u32)len;
 
+        if (filename.length() > 4 && filename.substr(filename.length() - 4) == ".zst")
+        {
+            u8* outContent = nullptr;
+            u32 decompressed = DecompressROM(filedata, len, &outContent);
+
+            if (decompressed > 0)
+            {
+                delete[] filedata;
+                filedata = outContent;
+                filelen = decompressed;
+                filename = filename.substr(0, filename.length() - 4);
+            }
+            else
+            {
+                delete[] filedata;
+                return false;
+            }
+        }
+
         int pos = LastSep(filename);
         if(pos != -1)
             basepath = filename.substr(0, pos);
@@ -543,14 +584,14 @@ bool LoadROM(QStringList filepath, bool reset)
     {
         // file inside archive
 
-            s32 lenread = Archive::ExtractFileFromArchive(filepath.at(0), filepath.at(1), &filedata, &filelen);
-            if (lenread < 0) return false;
-            if (!filedata) return false;
-            if (lenread != filelen)
-            {
-                delete[] filedata;
-                return false;
-            }
+        s32 lenread = Archive::ExtractFileFromArchive(filepath.at(0), filepath.at(1), &filedata, &filelen);
+        if (lenread < 0) return false;
+        if (!filedata) return false;
+        if (lenread != filelen)
+        {
+            delete[] filedata;
+            return false;
+        }
 
         std::string std_archivepath = filepath.at(0).toStdString();
         basepath = std_archivepath.substr(0, LastSep(std_archivepath));
@@ -695,6 +736,25 @@ bool LoadGBAROM(QStringList filepath)
         fclose(f);
         filelen = (u32)len;
 
+        if (filename.length() > 4 && filename.substr(filename.length() - 4) == ".zst")
+        {
+            u8* outContent = nullptr;
+            u32 decompressed = DecompressROM(filedata, len, &outContent);
+
+            if (decompressed > 0)
+            {
+                delete[] filedata;
+                filedata = outContent;
+                filelen = decompressed;
+                filename = filename.substr(0, filename.length() - 4);
+            }
+            else
+            {
+                delete[] filedata;
+                return false;
+            }
+        }
+
         int pos = LastSep(filename);
         basepath = filename.substr(0, pos);
         romname = filename.substr(pos+1);
diff --git a/src/frontend/qt_sdl/main.cpp b/src/frontend/qt_sdl/main.cpp
index 518d5f5..9200538 100644
--- a/src/frontend/qt_sdl/main.cpp
+++ b/src/frontend/qt_sdl/main.cpp
@@ -146,7 +146,7 @@ const QStringList ArchiveExtensions
     ".tar.lz",
     ".tar.lzma", ".tlz",
     ".tar.lrz", ".tlrz",
-    ".tar.lzo", ".tzo",
+    ".tar.lzo", ".tzo"
 #endif
 };
 
@@ -1568,9 +1568,23 @@ static bool SupportedArchiveByMimetype(const QMimeType& mimetype)
     return MimeTypeInList(mimetype, ArchiveMimeTypes);
 }
 
+static bool ZstdNdsRomByExtension(const QString& filename)
+{
+    if (filename.endsWith(".zst", Qt::CaseInsensitive))
+        return NdsRomByExtension(filename.left(filename.size() - 4));
+}
+
+static bool ZstdGbaRomByExtension(const QString& filename)
+{
+    if (filename.endsWith(".zst", Qt::CaseInsensitive))
+        return GbaRomByExtension(filename.left(filename.size() - 4));
+}
 
 static bool FileIsSupportedFiletype(const QString& filename, bool insideArchive = false)
 {
+    if (ZstdNdsRomByExtension(filename) || ZstdGbaRomByExtension(filename))
+        return true;
+
     if (NdsRomByExtension(filename) || GbaRomByExtension(filename) || SupportedArchiveByExtension(filename))
         return true;
 
@@ -2207,7 +2221,12 @@ void MainWindow::dropEvent(QDropEvent* event)
     const auto matchMode = romInsideArchive ? QMimeDatabase::MatchExtension : QMimeDatabase::MatchDefault;
     const QMimeType mimetype = QMimeDatabase().mimeTypeForFile(filename, matchMode);
 
-    if (NdsRomByExtension(filename) || NdsRomByMimetype(mimetype))
+    bool isNdsRom = NdsRomByExtension(filename) || NdsRomByMimetype(mimetype);
+    bool isGbaRom = GbaRomByExtension(filename) || GbaRomByMimetype(mimetype);
+    isNdsRom |= ZstdNdsRomByExtension(filename);
+    isGbaRom |= ZstdGbaRomByExtension(filename);
+
+    if (isNdsRom)
     {
         if (!ROMManager::LoadROM(file, true))
         {
@@ -2227,7 +2246,7 @@ void MainWindow::dropEvent(QDropEvent* event)
 
         updateCartInserted(false);
     }
-    else if (GbaRomByExtension(filename) || GbaRomByMimetype(mimetype))
+    else if (isGbaRom)
     {
         if (!ROMManager::LoadGBAROM(file))
         {
@@ -2452,14 +2471,25 @@ QStringList MainWindow::pickROM(bool gba)
     const QString console = gba ? "GBA" : "DS";
     const QStringList& romexts = gba ? GbaRomExtensions : NdsRomExtensions;
 
-    static const QString filterSuffix = ArchiveExtensions.empty()
-        ? ");;Any file (*.*)"
-        : " *" + ArchiveExtensions.join(" *") + ");;Any file (*.*)";
+    QString rawROMs = romexts.join(" *");
+    QString extraFilters = ";;" + console + " ROMs (*" + rawROMs;
+    QString allROMs = rawROMs;
+
+    QString zstdROMs = "*" + romexts.join(".zst *") + ".zst";
+    extraFilters += ");;Zstandard-compressed " + console + " ROMs (" + zstdROMs + ")";
+    allROMs += " " + zstdROMs;
+
+#ifdef ARCHIVE_SUPPORT_ENABLED
+    QString archives = "*" + ArchiveExtensions.join(" *");
+    extraFilters += ";;Archives (" + archives + ")";
+    allROMs += " " + archives;
+#endif
+    extraFilters += ";;All files (*.*)";
 
     const QString filename = QFileDialog::getOpenFileName(
         this, "Open " + console + " ROM",
         QString::fromStdString(Config::LastROMFolder),
-        console + " ROMs (*" + romexts.join(" *") + filterSuffix
+        "All supported files (*" + allROMs + ")" + extraFilters
     );
 
     if (filename.isEmpty()) return {};