Implement portamento up and down for psg channels

src/reskit/soundtrack/engines/echo/engine.rs

@@ -1,4 +1,4 @@
-use std::{collections::HashMap, error::Error};
+use std::{collections::HashMap, error::Error, cmp::{min, max}};
 use linked_hash_set::LinkedHashSet;
 use crate::reskit::{soundtrack::types::{PatternRow, Note, Channel, OctaveFrequency, Effect, Instrument}, utility::print_warning};
 
@@ -107,7 +107,7 @@ pub fn get_pcm_index( note: &Note ) -> Result<u8, Box<dyn Error>> {
     D  - 722 | F# - 910 | A# - 1146
     D# - 765 | G  - 964 | B  - 1214
 */
-pub fn get_semitone_frequency( semitone: u8 ) -> Result<u16, Box<dyn Error>> {
+pub fn get_fm_semitone_frequency( semitone: u8 ) -> Result<u16, Box<dyn Error>> {
     Ok( match semitone {
         ESF_SEMITONE_C => 644,
         ESF_SEMITONE_C_SHARP => 681,
@@ -121,10 +121,65 @@ pub fn get_semitone_frequency( semitone: u8 ) -> Result<u16, Box<dyn Error>> {
         ESF_SEMITONE_A => 1081,
         ESF_SEMITONE_A_SHARP => 1146,
         ESF_SEMITONE_B => 1214,
-        _ => return Err( "internal error: invalid semitone value provided to get_semitone_frequency" )?
+        _ => return Err( "internal error: invalid semitone value provided to get_fm_semitone_frequency" )?
     } )
 }
 
+/**
+ * Gets the semitone frequency used by Echo (PSG).
+   https://github.com/sikthehedgehog/Echo/blob/master/doc/esf.txt#L273
+       |Oct.0|Oct.1|Oct.2|Oct.3|Oct.4|Oct.5
+    ---|-----|-----|-----|-----|-----|-----
+    C  | 851 | 425 | 212 | 106 |  53 |  26
+    C# | 803 | 401 | 200 | 100 |  50 |  25
+    D  | 758 | 379 | 189 |  94 |  47 |  23
+    D# | 715 | 357 | 178 |  89 |  44 |  22
+    E  | 675 | 337 | 168 |  84 |  42 |  21
+    F  | 637 | 318 | 159 |  79 |  39 |  19
+    F# | 601 | 300 | 150 |  75 |  37 |  18
+    G  | 568 | 284 | 142 |  71 |  35 |  17
+    G# | 536 | 268 | 134 |  67 |  33 |  16
+    A  | 506 | 253 | 126 |  63 |  31 |  15
+    A# | 477 | 238 | 119 |  59 |  29 |  14
+    B  | 450 | 225 | 112 |  56 |  28 |  14
+ */
+pub fn get_psg_semitone_frequency( octave: u8, semitone: u8 ) -> Result<u16, Box<dyn Error>> {
+    Ok( match semitone {
+        ESF_SEMITONE_C => match octave { 0 => 851, 1 => 425, 2 => 212, 3 => 106, 4 => 53, 5 | _ => 26 },
+        ESF_SEMITONE_C_SHARP => match octave { 0 => 803, 1 => 401, 2 => 200, 3 => 100, 4 => 50, 5 | _ => 25 },
+        ESF_SEMITONE_D => match octave { 0 => 758, 1 => 379, 2 => 189, 3 => 94, 4 => 47, 5 | _ => 23 },
+        ESF_SEMITONE_D_SHARP => match octave { 0 => 715, 1 => 357, 2 => 178, 3 => 89, 4 => 44, 5 | _ => 22 },
+        ESF_SEMITONE_E => match octave { 0 => 675, 1 => 337, 2 => 168, 3 => 84, 4 => 42, 5 | _ => 21 },
+        ESF_SEMITONE_F => match octave { 0 => 637, 1 => 318, 2 => 159, 3 => 79, 4 => 39, 5 | _ => 19 },
+        ESF_SEMITONE_F_SHARP => match octave { 0 => 601, 1 => 300, 2 => 150, 3 => 75, 4 => 37, 5 | _ => 18 },
+        ESF_SEMITONE_G => match octave { 0 => 568, 1 => 284, 2 => 142, 3 => 71, 4 => 35, 5 | _ => 17 },
+        ESF_SEMITONE_G_SHARP => match octave { 0 => 536, 1 => 268, 2 => 134, 3 => 67, 4 => 33, 5 | _ => 16 },
+        ESF_SEMITONE_A => match octave { 0 => 506, 1 => 253, 2 => 126, 3 => 63, 4 => 31, 5 | _ => 15 },
+        ESF_SEMITONE_A_SHARP => match octave { 0 => 477, 1 => 238, 2 => 119, 3 => 59, 4 => 29, 5 | _ => 14 },
+        ESF_SEMITONE_B => match octave { 0 => 450, 1 => 225, 2 => 112, 3 => 56, 4 => 28, 5 | _ => 14 },
+        _ => return Err( "internal error: invalid semitone value provided to get_psg_semitone_frequency" )?
+    } )
+}
+
+/**
+ * Convenience method to get the octave of a given PSG frequency
+ */
+pub fn get_psg_octave_from_frequency( frequency: i16 ) -> u8 {
+    if frequency > 425 {
+        0
+    } else if frequency > 212 && frequency <= 425 {
+        1
+    } else if frequency > 106 && frequency <= 212 {
+        2
+    } else if frequency > 53 && frequency <= 106 {
+        3
+    } else if frequency > 26 && frequency <= 53 {
+        4
+    } else {
+        5
+    }
+}
+
 pub fn get_fm_note_byte( octave: u8, semitone: u8 ) -> u8 {
     32 * octave + 2 * semitone + 1
 }
@@ -190,7 +245,7 @@ pub fn get_events_for_channel( channel: &mut Channel, row: &PatternRow, pcm_offs
     } else {
         // This is SN1, SN2, or SN3 with no active instrument
         // Check if the channel needs "__reskit_default_psg_instrument" set before a note is set
-        if channel.active_instrument.is_none() && ( 6..=8 ).contains( &channel.id ) {
+        if channel.active_instrument.is_none() && ( ESF_PSG_1..=ESF_PSG_3 ).contains( &channel.id ) {
             if row.note.is_some() {
                 // Set "__reskit_default_psg_instrument"
                 let instrument = default_psg_instr_index.ok_or( "internal error: no default psg instrument to apply" )?;
@@ -210,7 +265,11 @@ pub fn get_events_for_channel( channel: &mut Channel, row: &PatternRow, pcm_offs
             channel.active_note = Some(
                 OctaveFrequency {
                     octave: note.get_octave()?,
-                    frequency: get_semitone_frequency( get_semitone( note )? )?
+                    frequency: if ( ESF_PSG_1..=ESF_PSG_3 ).contains( &channel.id ) {
+                        get_psg_semitone_frequency( note.get_octave()?, get_semitone( note )? )?
+                    } else {
+                        get_fm_semitone_frequency( get_semitone( note )? )?
+                    }
                 }
             );
 
@@ -418,29 +477,41 @@ pub fn get_portamento( channel: &mut Channel, portamento_effect: &Effect ) -> Re
                     _ => return Err( "internal error: provided effect is not a supported portamento effect" )?
                 };
 
+                if ( ESF_PSG_1..=ESF_PSG_3 ).contains( &channel.id ) {
+                    // Frequency note shifts are backward in PSG
+                    let new_frequency: i16 = octave_frequency.frequency as i16 + ( by_amount * -1 );
+
+                    // Clamp frequency
+                    let new_frequency = max( min( new_frequency, 1024 ), 0 );
+
+                    // Get psg octave from frequency (which will clamp octave to 0-5) and return the new frequency
+                    ( get_psg_octave_from_frequency( new_frequency ), new_frequency as u16 )
+                } else {
                     let new_frequency: i16 = octave_frequency.frequency as i16 + by_amount;
-                if new_frequency > get_semitone_frequency( ESF_SEMITONE_B )? as i16 {
+
+                    if new_frequency > get_fm_semitone_frequency( ESF_SEMITONE_B )? as i16 {
                         if octave_frequency.octave == 7 {
                             // Nowhere else to go up
-                        ( 7, get_semitone_frequency( ESF_SEMITONE_B )? )
+                            ( 7, get_fm_semitone_frequency( ESF_SEMITONE_B )? )
                         } else {
                             // Go up an octave then add the difference to middle C
-                        let difference = new_frequency - get_semitone_frequency( ESF_SEMITONE_B )? as i16;
+                            let difference = new_frequency - get_fm_semitone_frequency( ESF_SEMITONE_B )? as i16;
-                        ( octave_frequency.octave + 1, get_semitone_frequency( ESF_SEMITONE_C )? + difference as u16 )
+                            ( octave_frequency.octave + 1, get_fm_semitone_frequency( ESF_SEMITONE_C )? + difference as u16 )
                         }
-                } else if new_frequency < get_semitone_frequency( ESF_SEMITONE_C )? as i16 {
+                    } else if new_frequency < get_fm_semitone_frequency( ESF_SEMITONE_C )? as i16 {
                         if octave_frequency.octave == 0 {
                             // Nowhere else to go down
-                        ( 0, get_semitone_frequency( ESF_SEMITONE_C )? )
+                            ( 0, get_fm_semitone_frequency( ESF_SEMITONE_C )? )
                         } else {
                             // Go down an octave then subtract the overshoot of C from B
-                        let difference = get_semitone_frequency( ESF_SEMITONE_C )? as i16 - new_frequency;
+                            let difference = get_fm_semitone_frequency( ESF_SEMITONE_C )? as i16 - new_frequency;
-                        ( octave_frequency.octave - 1, get_semitone_frequency( ESF_SEMITONE_B )? - difference as u16 )
+                            ( octave_frequency.octave - 1, get_fm_semitone_frequency( ESF_SEMITONE_B )? - difference as u16 )
                         }
                     } else {
                         // Move within the same octave
                         ( octave_frequency.octave, new_frequency as u16 )
                     }
+                }
             };
 
             // Set the new OctaveFrequency on the channel
@@ -450,8 +521,16 @@ pub fn get_portamento( channel: &mut Channel, portamento_effect: &Effect ) -> Re
             // YM2612 register format for frequency: https://plutiedev.com/ym2612-registers#reg-A0
             vec![
                 ESF_SET_FREQUENCY | channel.id,
-                octave << 3 | ( ( ( 0x0700 & frequency ) >> 8 ) as u8 ),
+                if ( ESF_PSG_1..=ESF_PSG_3 ).contains( &channel.id ) {
+                    ( 0x000F & frequency ) as u8
+                } else {
+                    octave << 3 | ( ( ( 0x0700 & frequency ) >> 8 ) as u8 )
+                },
+                if ( ESF_PSG_1..=ESF_PSG_3 ).contains( &channel.id ) {
+                    ( ( 0x3F0 & frequency ) >> 4 ) as u8
+                } else {
                     ( 0x00FF & frequency ) as u8
+                }
             ]
         } else {
             // No active note, nothing to generate