Add sample offset command support

tracker/agb-tracker-interop/src/lib.rs

@@ -93,6 +93,7 @@ pub enum PatternEffect {
     /// Increase / decrease the pitch by the specified amount immediately
     PitchBend(Num<u32, 8>),
     Jump(Jump),
+    SampleOffset(u16),
 }
 
 #[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
@@ -401,6 +402,7 @@ impl quote::ToTokens for PatternEffect {
             PatternEffect::Jump(jump) => {
                 quote! { Jump(#jump) }
             }
+            PatternEffect::SampleOffset(offset) => quote! { SampleOffset(#offset) },
         };
 
         tokens.append_all(quote! {

tracker/agb-tracker/src/lib.rs

@@ -126,6 +126,9 @@ struct TrackerChannel {
     current_speed: Num<u32, 16>,
     current_panning: Num<i32, 8>,
     is_playing: bool,
+
+    // if some, should set the current position to this
+    current_pos: Option<u16>,
 }
 
 #[derive(Default)]
@@ -337,6 +340,10 @@ impl<'track, TChannelId> TrackerInner<'track, TChannelId> {
                 channel.volume(tracker_channel.current_volume.try_change_base().unwrap());
                 channel.panning(tracker_channel.current_panning.try_change_base().unwrap());
 
+                if let Some(offset) = tracker_channel.current_pos.take() {
+                    channel.set_pos(offset as u32);
+                }
+
                 if tracker_channel.is_playing {
                     channel.resume();
                 } else {
@@ -601,6 +608,11 @@ impl TrackerChannel {
             PatternEffect::Jump(jump) => {
                 *current_jump = Some(jump.clone());
             }
+            PatternEffect::SampleOffset(offset) => {
+                if tick == 0 {
+                    self.current_pos = Some(*offset);
+                }
+            }
         }
     }
 
@@ -677,6 +689,10 @@ impl SoundChannel for agb::sound::mixer::SoundChannel {
     fn panning(&mut self, panning: impl Into<Num<i16, 8>>) -> &mut Self {
         self.panning(panning)
     }
+
+    fn set_pos(&mut self, pos: impl Into<Num<u32, 8>>) -> &mut Self {
+        self.set_pos(pos)
+    }
 }
 
 #[cfg(feature = "agb")]

tracker/agb-tracker/src/mixer.rs

@@ -17,6 +17,8 @@ pub trait SoundChannel {
     fn restart_point(&mut self, value: impl Into<Num<u32, 8>>) -> &mut Self;
     fn playback(&mut self, playback_speed: impl Into<Num<u32, 8>>) -> &mut Self;
     fn panning(&mut self, panning: impl Into<Num<i16, 8>>) -> &mut Self;
+
+    fn set_pos(&mut self, pos: impl Into<Num<u32, 8>>) -> &mut Self;
 }
 
 pub trait Mixer {

tracker/agb-xm-core/src/lib.rs

@@ -324,6 +324,7 @@ pub fn parse_module(module: &Module) -> agb_tracker_interop::Track {
                             )
                         }
                     }
+                    0x9 => PatternEffect::SampleOffset(effect_parameter as u16 * 256),
                     0xB => {
                         let pattern_idx = slot.effect_parameter;
 

tracker/desktop-player/src/mixer.rs

@@ -171,6 +171,11 @@ impl agb_tracker::SoundChannel for SoundChannel {
         self.panning = panning.into();
         self
     }
+
+    fn set_pos(&mut self, pos: impl Into<Num<u32, 8>>) -> &mut Self {
+        self.pos = pos.into();
+        self
+    }
 }
 
 impl agb_tracker::Mixer for Mixer {