Support changing overall playing speed at runtime, using a slider or a MIDI controller.

[nageru] / shared / midi_mapper_util.h

diff --git a/shared/midi_mapper_util.h b/shared/midi_mapper_util.h
index 39ccd84e43f7d1ec1e707e2de730ea1d08ad59d9..5b66b83710f863e74bf5ab8f28cc0d37928a69ea 100644 (file)
--- a/shared/midi_mapper_util.h
+++ b/shared/midi_mapper_util.h
@@ -2,6 +2,7 @@
 #define _MIDI_MAPPER_UTIL_H 1
 
 #include "midi_mapping.pb.h"
+#include "shared/midi_device.h"
 
 #include <google/protobuf/descriptor.h>
 
@@ -61,4 +62,31 @@ void activate_mapped_light(const Proto &msg, int field_number, std::set<unsigned
        active_lights->insert(light_proto.note_number());
 }
 
+inline double map_controller_to_float(int controller, int val)
+{
+       if (controller == MIDIReceiver::PITCH_BEND_CONTROLLER) {
+               // We supposedly go from -8192 to 8191 (inclusive), but there are
+               // controllers that only have 10-bit precision and do the upconversion
+               // to 14-bit wrong (just padding with zeros), making 8176 the highest
+               // attainable value. We solve this by making the effective range
+               // -8176..8176 (inclusive).
+               if (val <= -8176) {
+                       return 0.0;
+               } else if (val >= 8176) {
+                       return 1.0;
+               } else {
+                       return 0.5 * (double(val) / 8176.0) + 0.5;
+               }
+       }
+
+       // Slightly hackish mapping so that we can represent exactly 0.0, 0.5 and 1.0.
+       if (val <= 0) {
+               return 0.0;
+       } else if (val >= 127) {
+               return 1.0;
+       } else {
+               return (val + 0.5) / 127.0;
+       }
+}
+
 #endif  // !defined(_MIDI_MAPPER_UTIL_H)