G2.1: save full instrument state to disk (path/type/preset/transport)

native_bridge/src/Vst3Instrument.cpp

@@ -549,6 +549,44 @@ void Vst3Instrument::captureState() {
 #endif
 }
 
+// G2.1: base64 encode (RFC 4648). Small, dependency-free.
+static std::string base64Encode(const uint8_t* data, size_t len) {
+    static const char* tbl = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+    std::string out;
+    out.reserve(((len + 2) / 3) * 4);
+    for (size_t i = 0; i < len; i += 3) {
+        uint32_t n = (uint32_t)data[i] << 16;
+        if (i + 1 < len) n |= (uint32_t)data[i + 1] << 8;
+        if (i + 2 < len) n |= (uint32_t)data[i + 2];
+        out += tbl[(n >> 18) & 63];
+        out += tbl[(n >> 12) & 63];
+        out += (i + 1 < len) ? tbl[(n >> 6) & 63] : '=';
+        out += (i + 2 < len) ? tbl[n & 63] : '=';
+    }
+    return out;
+}
+
+std::string Vst3Instrument::serializeState() const {
+#ifndef HAVE_VST3SDK
+    return std::string();
+#else
+    if (savedComponentState_.empty() && savedControllerState_.empty())
+        return std::string();
+    std::vector<uint8_t> blob;
+    auto append32 = [&blob](uint32_t v) {
+        blob.push_back((uint8_t)(v >> 24));
+        blob.push_back((uint8_t)(v >> 16));
+        blob.push_back((uint8_t)(v >> 8));
+        blob.push_back((uint8_t)v);
+    };
+    append32((uint32_t)savedComponentState_.size());
+    blob.insert(blob.end(), savedComponentState_.begin(), savedComponentState_.end());
+    append32((uint32_t)savedControllerState_.size());
+    blob.insert(blob.end(), savedControllerState_.begin(), savedControllerState_.end());
+    return base64Encode(blob.data(), blob.size());
+#endif
+}
+
 // G0.4: restore the captured state onto the freshly loaded instance.
 void Vst3Instrument::restoreState() {
 #ifndef HAVE_VST3SDK