rudimentary input quantizer

src/core/midi.rs

@@ -35,3 +35,51 @@ pub fn write_midi_output (writer: &mut ::jack::MidiWriter, output: &MIDIChunk, f
         }
     }
 }
+
+/// (ppq, name)
+pub const NOTE_DURATIONS: [(usize, &str);16] = [
+    (1,   "1/384"),
+    (2,   "1/192"),
+    (3,   "1/128"),
+    (4,   "1/96"),
+    (6,   "1/64"),
+    (8,   "1/48"),
+    (12,  "1/32"),
+    (16,  "1/24"),
+    (24,  "1/16"),
+    (32,  "1/12"),
+    (48,  "1/8"),
+    (64,  "1/6"),
+    (96,  "1/4"),
+    (128, "1/3"),
+    (192, "1/2"),
+    (384, "1/1"),
+];
+
+pub fn ppq_to_name (ppq: usize) -> &'static str {
+    for (length, name) in &NOTE_DURATIONS {
+        if *length == ppq {
+            return name
+        }
+    }
+    ""
+}
+
+pub fn prev_note_length (ppq: usize) -> usize {
+    for i in 1..=16 {
+        let length = NOTE_DURATIONS[16-i].0;
+        if length < ppq {
+            return length
+        }
+    }
+    ppq
+}
+
+pub fn next_note_length (ppq: usize) -> usize {
+    for (length, _) in &NOTE_DURATIONS {
+        if *length > ppq {
+            return *length
+        }
+    }
+    ppq
+}