Attempt to calculate the speed to play more correctly

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

@@ -10,7 +10,8 @@ pub struct Track<'a> {
     pub patterns_to_play: &'a [usize],
 
     pub num_channels: usize,
-    pub frames_per_step: u16,
+    pub frames_per_tick: Num<u16, 8>,
+    pub ticks_per_step: u16,
 }
 
 #[derive(Debug)]
@@ -45,11 +46,14 @@ impl<'a> quote::ToTokens for Track<'a> {
             samples,
             pattern_data,
             patterns,
-            frames_per_step,
+            frames_per_tick,
             num_channels,
             patterns_to_play,
+            ticks_per_step,
         } = self;
 
+        let frames_per_tick = frames_per_tick.to_raw();
+
         tokens.append_all(quote! {
             {
                 const SAMPLES: &[agb_tracker::__private::agb_tracker_interop::Sample<'static>] = &[#(#samples),*];
@@ -63,8 +67,9 @@ impl<'a> quote::ToTokens for Track<'a> {
                     patterns: PATTERNS,
                     patterns_to_play: PATTERNS_TO_PLAY,
 
-                    frames_per_step: #frames_per_step,
+                    frames_per_tick: agb_tracker::__private::Num::from_raw(#frames_per_tick),
                     num_channels: #num_channels,
+                    ticks_per_step: #ticks_per_step,
                 }
             }
         })

tracker/agb-tracker/src/lib.rs

@@ -9,7 +9,10 @@ extern crate alloc;
 
 use alloc::vec::Vec;
 
-use agb::sound::mixer::{ChannelId, Mixer, SoundChannel};
+use agb::{
+    fixnum::Num,
+    sound::mixer::{ChannelId, Mixer, SoundChannel},
+};
 
 #[cfg(feature = "xm")]
 pub use agb_xm::import_xm;
@@ -25,7 +28,9 @@ pub struct Tracker {
     track: &'static Track<'static>,
     channels: Vec<Option<ChannelId>>,
 
-    step: u16,
+    frame: Num<u16, 8>,
+    tick: u16,
+
     current_row: usize,
     current_pattern: usize,
 }
@@ -39,14 +44,16 @@ impl Tracker {
             track,
             channels,
 
-            step: 0,
+            frame: 0.into(),
+            tick: 0,
+
             current_row: 0,
             current_pattern: 0,
         }
     }
 
     pub fn step(&mut self, mixer: &mut Mixer) {
-        if self.step != 0 {
+        if self.tick != 0 {
             self.increment_step();
             return; // TODO: volume / pitch slides
         }
@@ -113,9 +120,14 @@ impl Tracker {
     }
 
     fn increment_step(&mut self) {
-        self.step += 1;
+        self.frame += 1;
 
-        if self.step == self.track.frames_per_step {
+        if self.frame >= self.track.frames_per_tick {
+            self.tick += 1;
+            self.frame -= self.track.frames_per_tick;
+        }
+
+        if self.tick == self.track.ticks_per_step {
             self.current_row += 1;
 
             if self.current_row
@@ -129,7 +141,7 @@ impl Tracker {
                 }
             }
 
-            self.step = 0;
+            self.tick = 0;
         }
     }
 }

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

@@ -202,6 +202,10 @@ pub fn parse_module(module: &Module) -> TokenStream {
         .map(|order| *order as usize)
         .collect::<Vec<_>>();
 
+    // Number 150 here deduced experimentally
+    let frames_per_tick = Num::<u16, 8>::new(150) / module.default_bpm;
+    let ticks_per_step = module.default_tempo;
+
     let interop = agb_tracker_interop::Track {
         samples: &samples,
         pattern_data: &pattern_data,
@@ -209,7 +213,8 @@ pub fn parse_module(module: &Module) -> TokenStream {
         num_channels: module.get_num_channels(),
         patterns_to_play: &patterns_to_play,
 
-        frames_per_step: 4, // TODO calculate this correctly
+        frames_per_tick,
+        ticks_per_step,
     };
 
     quote!(#interop)