Play PCM samples in ESF stream

src/reskit/soundtrack/engines/echo.rs

@@ -82,6 +82,27 @@ fn get_semitone( note: &Note ) -> Result<u8, Box<dyn Error>> {
     } )
 }
 
+/**
+ * Notes are used to index PCM sample playback. C = 1, etc.
+ */
+fn get_pcm_index( note: &Note ) -> Result<u8, Box<dyn Error>> {
+    Ok( match note {
+        Note::NoteOff => return Err( "internal error: attempted to get pcm index for a Note::NoteOff" )?,
+        Note::C(_) => 0,
+        Note::CSharp(_) => 1,
+        Note::D(_) => 2,
+        Note::DSharp(_) => 3,
+        Note::E(_) => 4,
+        Note::F(_) => 5,
+        Note::FSharp(_) => 6,
+        Note::G(_) => 7,
+        Note::GSharp(_) => 8,
+        Note::A(_) => 9,
+        Note::ASharp(_) => 10,
+        Note::B(_) => 11
+    } )
+}
+
 /**
   Gets the semitone frequency used by Echo.
   https://github.com/sikthehedgehog/Echo/blob/master/doc/esf.txt#L243
@@ -235,15 +256,8 @@ fn get_events_for_channel( channel: &mut Channel, row: &PatternRow ) -> Result<V
     // Key on or key off note
     if let Some( note ) = &row.note {
         if let Note::NoteOff = note {
-            if channel.id == ESF_FM_6_PCM {
-                // TODO: Completely different scenario required for PCM channel
-            } else {
             channel.active_note = None;
             events.push( vec![ ESF_NOTE_OFF | channel.id ] );
-            }
-        } else {
-            if channel.id == ESF_FM_6_PCM {
-                // TODO: Completely different scenario required for PCM channel
         } else {
             channel.active_note = Some(
                 OctaveFrequency {
@@ -252,6 +266,9 @@ fn get_events_for_channel( channel: &mut Channel, row: &PatternRow ) -> Result<V
                 }
             );
 
+            if channel.id == ESF_FM_6_PCM {
+                events.push( vec![ ESF_NOTE_ON | channel.id, get_pcm_index( note )? ] );
+            } else {
                 let note = get_note( note, channel.id )?;
                 events.push( vec![ ESF_NOTE_ON | channel.id, note ] );
             }