From a1823d3f9568aac9eeafc91e444744906440ded8 Mon Sep 17 00:00:00 2001
From: Chris Xiong <chirs241097@gmail.com>
Date: Wed, 21 Dec 2022 22:46:55 -0500
Subject: Convert tempo effects.

Introducing an it2midi-specific swing on/off command to aid
real bpm calculation when legacy swing technique is used in
the file.
---
 src/convert.rs | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/utils.rs   | 14 ++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/src/convert.rs b/src/convert.rs
index a8aeb1a..c864400 100644
--- a/src/convert.rs
+++ b/src/convert.rs
@@ -18,6 +18,7 @@ struct PlayerState
     speed: u8,
     tempo: u8,
     rpb: u8,
+    swing_speed: Option<Rational>,
     loop_start: u8,
     loop_ctr: u8,
     row_extension: u8,
@@ -92,6 +93,31 @@ impl<'a, 'b> Player<'a, 'b>
                 Effect::PattLoopStart => PlayerState{loop_start: ps.current_row, ..ps},
                 Effect::SetTempo(t) => PlayerState{tempo: t, ..ps},
                 Effect::RowExtention(t) => PlayerState{row_extension: ps.row_extension + t, ..ps},
+                Effect::SetVibWaveform(0xe) => { //proprietary command: enter swing mode
+                    let mut ticks = 0;
+                    let mut ts = ps.speed;
+                    for r in ps.current_row..ps.current_row + ps.rpb
+                    {
+                        let pat = &self.it.patterns[self.it.orders[ps.current_ord as usize] as usize];
+                        for c in 0..pat.nch
+                        {
+                            let rcell = pat.cell_at(r, c);
+                            if rcell.mask & 0x88 != 0
+                            {
+                                let fx = Effect::from_it_efx((rcell.efx, rcell.fxp));
+                                match fx
+                                {
+                                    Effect::SetSpeed(a) => ts = a,
+                                    _ => ()
+                                }
+                            }
+                        }
+                        ticks += ts;
+                    }
+                    let swing_speed = Some(Rational::from(ticks) / Rational::from(ps.rpb));
+                    PlayerState{swing_speed, ..ps}
+                },
+                Effect::SetVibWaveform(0xf) => PlayerState{swing_speed: None, ..ps}, //proprietary command: exit swing mode
                 _ => ps
             }
         }
@@ -178,6 +204,7 @@ impl<'a, 'b> Player<'a, 'b>
             speed: self.it.header.speed,
             tempo: self.it.header.tempo,
             rpb: self.it.time_signature().unwrap_or((4, 16)).0 as u8,
+            swing_speed: None,
             loop_start: 0,
             loop_ctr: !0,
             row_extension: 0,
@@ -273,6 +300,32 @@ impl<'a, 'b> Converter<'a, 'b>
             }
             ret
         };
+        let tempofx = |ch: u8, cell, _chmem: Rc<RefCell<ChannelMemory>>, ps: PlayerState, t: Rational| {
+            if !ch == 0 || ps.in_rep { return Vec::new(); }
+            let mut ret = Vec::new();
+            let Cell { mask, efx, fxp, .. } = cell;
+            let fx = Effect::from_it_efx((efx, fxp));
+            if mask & 0x88 != 0
+            {
+                match fx
+                {
+                    Effect::SetSpeed(_) | Effect::SetTempo(_) |
+                    Effect::TempoSlideDown(_) | Effect::TempoSlideUp(_) |
+                    Effect::SetVibWaveform(0xe) | Effect::SetVibWaveform(0xf) =>
+                    {
+                        match ps.swing_speed
+                        {
+                            None => ret.push((TimedMidiEvent{ t: t.as_int_trunc() as u32, e: MidiEvent::MetaTempo(ps.tempo as f64 * 24. / ps.rpb as f64 / ps.speed as f64)}, (!0, !0))),
+                            Some(ss) => ret.push((TimedMidiEvent{ t: t.as_int_trunc() as u32, e: MidiEvent::MetaTempo((Rational::from(ps.tempo as u16 * 24) / Rational::from(ps.rpb) / ss).into())}, (!0, !0)))
+                        }
+                    }
+                    _ => ()
+                }
+            }
+            ret
+        };
+
+        self.fx_handlers.push(Box::new(RefCell::new(tempofx)));
         self.fx_handlers.push(Box::new(RefCell::new(nonfx)));
     }
     fn pre_pass(it: &ITFile) -> BTreeMap<(u8, u8), usize>
@@ -322,7 +375,11 @@ impl<'a, 'b> Converter<'a, 'b>
                 let Cell{mask, note, inst, vol: _, efx: _, fxp: _} = cell;
                 if !ch == 0
                 {
-                    self.miditick += <Rational as From<u32>>::from(960) / (ps.rpb as u16).into();
+                    match ps.swing_speed
+                    {
+                        None => self.miditick += Rational::from(960u32) / (ps.rpb as u16).into(),
+                        Some(ss) => self.miditick += Rational::from(960u32) / (ps.rpb as u16).into() * (Rational::from(ps.speed) / ss)
+                    }
                 }
                 if mask & 0x11 != 0 { self.chmem[ch as usize].borrow_mut().note = note; }
                 if mask & 0x22 != 0 { self.chmem[ch as usize].borrow_mut().inst = inst; }
diff --git a/src/utils.rs b/src/utils.rs
index cbe9716..0fc4328 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,4 +1,5 @@
 use std::ops::*;
+use std::fmt::{Debug, Formatter, Error};
 
 #[derive(Copy, Clone)]
 pub struct Rational
@@ -15,6 +16,14 @@ impl Default for Rational
     fn default() -> Rational { Rational::from_int(0) }
 }
 
+impl Debug for Rational
+{
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>
+    {
+        f.write_fmt(format_args!("{}/{}", self.n, self.d))
+    }
+}
+
 impl Add for Rational
 {
     type Output = Self;
@@ -70,6 +79,11 @@ impl From<u8> for Rational
     fn from(v: u8) -> Self { Rational::from_int(v as i64) }
 }
 
+impl From<Rational> for f64
+{
+    fn from(v: Rational) -> Self { v.n as f64 / v.d as f64 }
+}
+
 impl Rational
 {
     fn from_int(v: i64) -> Rational {Rational{n: v, d: 1}}
-- 
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