very, very simple WP with midi CC out

include/libremidi/detail/midi_out.hpp

@@ -0,0 +1,95 @@
+#pragma once
+#include <libremidi/cmidi2.hpp>
+#include <libremidi/detail/midi_api.hpp>
+#include <libremidi/output_configuration.hpp>
+
+#include <string_view>
+
+namespace libremidi
+{
+
+class midi_out_api : public midi_api
+{
+public:
+  midi_out_api() = default;
+  ~midi_out_api() override = default;
+  midi_out_api(const midi_out_api&) = delete;
+  midi_out_api(midi_out_api&&) = delete;
+  midi_out_api& operator=(const midi_out_api&) = delete;
+  midi_out_api& operator=(midi_out_api&&) = delete;
+
+  [[nodiscard]] virtual bool open_port(const output_port& pt, std::string_view local_port_name)
+      = 0;
+
+  [[nodiscard]] virtual int64_t current_time() const noexcept { return 0; }
+
+  virtual void send_message(const unsigned char* message, std::size_t size) = 0;
+  virtual void schedule_message(int64_t /*ts*/, const unsigned char* message, std::size_t size)
+  {
+    return send_message(message, size);
+  }
+
+  virtual void send_ump(const uint32_t* message, std::size_t size) = 0;
+  virtual void schedule_ump(int64_t /*ts*/, const uint32_t* ump, std::size_t size)
+  {
+    return send_ump(ump, size);
+  }
+};
+
+namespace midi1
+{
+class out_api : public midi_out_api
+{
+  friend struct midi_stream_decoder;
+
+public:
+  using midi_out_api::midi_out_api;
+
+  void send_ump(const uint32_t* message, std::size_t /*size*/)
+  {
+    uint8_t midi[65536];
+    const auto n
+        = cmidi2_convert_single_ump_to_midi1(midi, sizeof(midi), const_cast<uint32_t*>(message));
+    if (n > 0)
+      send_message(midi, n);
+  }
+};
+}
+
+namespace midi2
+{
+class out_api : public midi_out_api
+{
+  friend struct midi_stream_decoder;
+
+public:
+  using midi_out_api::midi_out_api;
+
+  void send_message(const unsigned char* message, std::size_t size)
+  {
+    cmidi2_midi_conversion_context context{};
+    cmidi2_midi_conversion_context_initialize(&context);
+
+    uint32_t ump[65536 / 4];
+
+    context.midi1 = const_cast<unsigned char*>(message);
+    context.midi1_num_bytes = size;
+    context.midi1_proceeded_bytes = 0;
+    context.ump = ump;
+    context.ump_num_bytes = sizeof(ump);
+    context.ump_proceeded_bytes = 0;
+
+    if (auto res = cmidi2_convert_midi1_to_ump(&context); res != CMIDI2_CONVERSION_RESULT_OK)
+      return;
+
+    send_ump(context.ump, context.ump_proceeded_bytes / 4);
+  }
+};
+}
+
+template <typename T, typename Arg>
+std::unique_ptr<midi_out_api> make(libremidi::output_configuration&& conf, Arg&& arg)
+{
+  return std::make_unique<T>(std::move(conf), std::forward<Arg>(arg));
+}
+}