Pass through getParameter and setParameter

src/common/communication.h

@@ -104,8 +104,6 @@ struct EventResult {
      */
     std::optional<std::string> data;
 
-    // TODO: Add missing return value fields;
-
     template <typename S>
     void serialize(S& s) {
         s.value8b(return_value);
@@ -114,6 +112,37 @@ struct EventResult {
     }
 };
 
+/**
+ * Represents a call to either `getParameter` or `setParameter`, depending on
+ * whether `value` contains a value or not.
+ */
+struct Parameter {
+    int32_t index;
+    std::optional<float> value;
+
+    template <typename S>
+    void serialize(S& s) {
+        s.value4b(index);
+        s.ext(value, bitsery::ext::StdOptional(),
+              [](S& s, auto& v) { s.value4b(v); });
+    }
+};
+
+/**
+ * The result of a `getParameter` or a `setParameter` call. For `setParameter`
+ * this struct won't contain any values and mostly acts as an acknowledgement
+ * from the Wine VST host.
+ */
+struct ParameterResult {
+    std::optional<float> value;
+
+    template <typename S>
+    void serialize(S& s) {
+        s.ext(value, bitsery::ext::StdOptional(),
+              [](S& s, auto& v) { s.value4b(v); });
+    }
+};
+
 /**
  * The serialization function for `AEffect` structs. This will s serialize all
  * of the values but it will not touch any of the pointer fields. That way you

src/plugin/host-bridge.cpp

@@ -72,6 +72,7 @@ HostBridge::HostBridge(audioMasterCallback host_callback)
       socket_acceptor(io_context, socket_endpoint),
       host_vst_dispatch(io_context),
       vst_host_callback(io_context),
+      host_vst_parameters(io_context),
       vst_host_aeffect(io_context),
       host_callback_function(host_callback),
       vst_host(find_wine_vst_host(),
@@ -84,6 +85,7 @@ HostBridge::HostBridge(audioMasterCallback host_callback)
     // in the Wine VST host
     socket_acceptor.accept(host_vst_dispatch);
     socket_acceptor.accept(vst_host_callback);
+    socket_acceptor.accept(host_vst_parameters);
     socket_acceptor.accept(vst_host_aeffect);
 
     // Set up all pointers for our `AEffect` struct. We will fill this with data
@@ -160,15 +162,22 @@ void HostBridge::process_replacing(AEffect* /*plugin*/,
 }
 
 void HostBridge::set_parameter(AEffect* /*plugin*/,
-                               int32_t /*index*/,
-                               float /*value*/) {
-    // TODO: Unimplmemented
+                               int32_t index,
+                               float value) {
+    Parameter request{index, value};
+    write_object(host_vst_parameters, request);
+
+    // This should not contain any values and just serve as an acknowledgement
+    const auto response = read_object<ParameterResult>(host_vst_parameters);
+    assert(!response.value.has_value());
 }
 
-float HostBridge::get_parameter(AEffect* /*plugin*/, int32_t /*index*/
-) {
-    // TODO: Unimplmemented
-    return 0.0f;
+float HostBridge::get_parameter(AEffect* /*plugin*/, int32_t index) {
+    Parameter request{index, std::nullopt};
+    write_object(host_vst_parameters, request);
+
+    const auto response = read_object<ParameterResult>(host_vst_parameters);
+    return response.value.value();
 }
 
 /**

src/plugin/host-bridge.h

@@ -84,6 +84,14 @@ class HostBridge {
     // plugin (through the Wine VST host).
     boost::asio::local::stream_protocol::socket host_vst_dispatch;
     boost::asio::local::stream_protocol::socket vst_host_callback;
+    /**
+     * Used for both `getParameter` and `setParameter` since they mostly
+     * overlap.
+     *
+     * TODO: Verify that these 100% won't be called simultanously since that
+     *       would cause a race condition.
+     */
+    boost::asio::local::stream_protocol::socket host_vst_parameters;
 
     /**
      * This socket only handles updates of the `AEffect` struct instead of

src/wine-host/plugin-bridge.cpp

@@ -57,6 +57,7 @@ PluginBridge::PluginBridge(std::string plugin_dll_path,
       socket_endpoint(socket_endpoint_path),
       host_vst_dispatch(io_context),
       vst_host_callback(io_context),
+      host_vst_parameters(io_context),
       vst_host_aeffect(io_context) {
     // Got to love these C APIs
     if (plugin_handle == nullptr) {
@@ -86,6 +87,7 @@ PluginBridge::PluginBridge(std::string plugin_dll_path,
     // in the Linus plugin
     host_vst_dispatch.connect(socket_endpoint);
     vst_host_callback.connect(socket_endpoint);
+    host_vst_parameters.connect(socket_endpoint);
     vst_host_aeffect.connect(socket_endpoint);
 
     // Initialize after communication has been set up We'll try to do the same
@@ -117,6 +119,30 @@ PluginBridge::PluginBridge(std::string plugin_dll_path,
             passthrough_event(host_vst_dispatch, plugin, plugin->dispatcher);
         }
     });
+
+    parameters_handler = std::thread([&]() {
+        while (true) {
+            // Both `getParameter` and `setParameter` functions are passed
+            // through on this socket since they have a lot of overlap. The
+            // presence of the `value` field tells us which one we're dealing
+            // with.
+            auto request = read_object<Parameter>(host_vst_parameters);
+            if (request.value.has_value()) {
+                // `setParameter`
+                plugin->setParameter(plugin, request.index,
+                                     request.value.value());
+
+                ParameterResult response{std::nullopt};
+                write_object(host_vst_parameters, response);
+            } else {
+                // `getParameter`
+                float value = plugin->getParameter(plugin, request.index);
+
+                ParameterResult response{value};
+                write_object(host_vst_parameters, response);
+            }
+        }
+    });
 }
 
 void PluginBridge::wait() {

src/wine-host/plugin-bridge.h

@@ -77,6 +77,11 @@ class PluginBridge {
     // plugin (through the Wine VST host).
     boost::asio::local::stream_protocol::socket host_vst_dispatch;
     boost::asio::local::stream_protocol::socket vst_host_callback;
+    /**
+     * Used for both `getParameter` and `setParameter` since they mostly
+     * overlap.
+     */
+    boost::asio::local::stream_protocol::socket host_vst_parameters;
 
     /**
      * This socket only handles updates of the `AEffect` struct instead of
@@ -89,6 +94,10 @@ class PluginBridge {
      * The thread that handles dispatch events from the host.
      */
     std::thread dispatch_handler;
+    /**
+     * The thread that responds to `getParameter` and `setParameter` requests.
+     */
+    std::thread parameters_handler;
 
-    // TODO: Set up all other callback handlers
+    // TODO: Set up process and processReplacing callback handlers
 };