Feat: add new words for new audio rate modulations

crates/forth/src/vm.rs

@@ -1433,7 +1433,7 @@ impl Forth {
                     let dur = pop_float(stack)? * ctx.step_duration();
                     let end = pop_float(stack)?;
                     let start = pop_float(stack)?;
-                    let suffix = match curve { 1 => "e", 2 => "s", _ => "" };
+                    let suffix = match curve { 1 => "e", 2 => "s", 3 => "i", 4 => "o", 5 => "p", _ => "" };
                     let s = format!("{start}>{end}:{dur}{suffix}");
                     stack.push(Value::Str(s.into(), None));
                 }

crates/forth/src/words/compile.rs

@@ -136,6 +136,9 @@ pub(super) fn simple_op(name: &str) -> Option<Op> {
         "slide" => Op::ModSlide(0),
         "expslide" => Op::ModSlide(1),
         "sslide" => Op::ModSlide(2),
+        "islide" => Op::ModSlide(3),
+        "oslide" => Op::ModSlide(4),
+        "pslide" => Op::ModSlide(5),
         "jit" => Op::ModRnd(0),
         "sjit" => Op::ModRnd(1),
         "drunk" => Op::ModRnd(2),

crates/forth/src/words/sound.rs

@@ -862,6 +862,36 @@ pub(super) const WORDS: &[Word] = &[
         compile: Simple,
         varargs: false,
     },
+    Word {
+        name: "islide",
+        aliases: &[],
+        category: "Audio Modulation",
+        stack: "(start end dur -- str)",
+        desc: "Swell transition (slow start, fast finish): start>end:duri",
+        example: "200 4000 1 islide lpf",
+        compile: Simple,
+        varargs: false,
+    },
+    Word {
+        name: "oslide",
+        aliases: &[],
+        category: "Audio Modulation",
+        stack: "(start end dur -- str)",
+        desc: "Pluck transition (fast attack, slow settle): start>end:duro",
+        example: "0 1 0.5 oslide gain",
+        compile: Simple,
+        varargs: false,
+    },
+    Word {
+        name: "pslide",
+        aliases: &[],
+        category: "Audio Modulation",
+        stack: "(start end dur -- str)",
+        desc: "Stair transition (8 discrete steps): start>end:durp",
+        example: "0 1 2 pslide gain",
+        compile: Simple,
+        varargs: false,
+    },
     Word {
         name: "jit",
         aliases: &[],