c api: fix raw / vs non-raw by checking which enum member waas set

fixes #150

Author: jcelerier

book/src/midi-2-integrations.md

@@ -13,6 +13,7 @@ See a basic `midi2_echo.cpp` example: it uses the following printing function:
 std::ostream& operator<<(std::ostream& s, const libremidi::ump& message)
 {
   // Automatic conversion from libremidi::ump& to cmidi2_ump*
+  // Note that cmidi2_ump is just a typedef for uint32_t.
   const cmidi2_ump* b = message;
 
   // Read MIDI 2 information

book/src/polling.md

@@ -7,7 +7,7 @@ which can then be injected into your app's main loop.
 
 Thus, this enables complete control over threading (and can also remove the need for synchronisation as this allows to make a callback-based yet single-threaded app, for simple applications which do not wish to reimplement MIDI filtering & parsing for back-ends such as ALSA Sequencer or RawMidi).
 
-Since this feature is pretty complicated to implement correctly, we recommend checking the examples: 
+Since this feature is pretty complicated to implement correctly unless you already have an easily accessible `poll` loop in your app, we recommend checking the examples: 
 
 See:
 - `poll_share.cpp` for a complete example for ALSA RawMidi (recommended).

include/libremidi/libremidi-c.cpp

@@ -276,11 +276,11 @@ int libremidi_midi_in_new(
             = [cb = c->get_timestamp](int64_t msg) { return cb.callback(cb.context, msg); };
       }
 
-      if (c->on_midi1_message.callback)
+      if (c->version == libremidi_midi_configuration::MIDI1 && c->on_midi1_message.callback)
         conf.on_message = [cb = c->on_midi1_message](const libremidi::message& msg) {
           cb.callback(cb.context, msg.timestamp, msg.bytes.data(), msg.size());
         };
-      else if (c->on_midi1_raw_data.callback)
+      else if (c->version == libremidi_midi_configuration::MIDI1_RAW && c->on_midi1_raw_data.callback)
       {
         conf.on_raw_data = [cb = c->on_midi1_raw_data](std::span<const uint8_t> msg, int64_t ts) {
           cb.callback(cb.context, ts, msg.data(), msg.size());
@@ -319,11 +319,11 @@ int libremidi_midi_in_new(
             = [cb = c->get_timestamp](int64_t msg) { return cb.callback(cb.context, msg); };
       }
 
-      if (c->on_midi2_message.callback)
+      if (c->version == libremidi_midi_configuration::MIDI2 && c->on_midi2_message.callback)
         conf.on_message = [cb = c->on_midi2_message](const libremidi::ump& msg) {
           cb.callback(cb.context, msg.timestamp, msg.data, msg.size());
         };
-      else if (c->on_midi2_raw_data.callback)
+      else if (c->version == libremidi_midi_configuration::MIDI2_RAW && c->on_midi2_raw_data.callback)
       {
         conf.on_raw_data = [cb = c->on_midi2_raw_data](std::span<const uint32_t> msg, int64_t ts) {
           cb.callback(cb.context, ts, msg.data(), msg.size());