From e2aec3161f791614fc19fc50a4dadf239d7422ad Mon Sep 17 00:00:00 2001
From: Grant Shangreaux <grant@unabridgedsoftware.com>
Date: Tue, 9 Nov 2021 20:51:57 -0600
Subject: Add: stub of asdr module / Envelope struct

---
 klangfarbrs/src/adsr.rs | 32 ++++++++++++++++++++++++++++++++
 klangfarbrs/src/lib.rs  |  2 ++
 2 files changed, 34 insertions(+)
 create mode 100644 klangfarbrs/src/adsr.rs

diff --git a/klangfarbrs/src/adsr.rs b/klangfarbrs/src/adsr.rs
new file mode 100644
index 0000000..ca03735
--- /dev/null
+++ b/klangfarbrs/src/adsr.rs
@@ -0,0 +1,32 @@
+use crate::{Millisecond, Amplitude};
+
+pub struct Envelope {
+    attack: Vec<Amplitude>,
+    decay: Vec<Amplitude>,
+    release: Vec<Amplitude>,
+}
+
+impl Envelope {
+    fn new(attack: Millisecond, decay: Millisecond, sustain: Amplitude, release: Millisecond) -> Self {
+        let attack = vec![sustain; attack as usize];
+        let decay = vec![sustain; decay as usize];
+        let release = vec![sustain; release as usize];
+
+        Self{attack, decay, release}
+    }
+
+    pub fn len(&self) -> usize {
+        self.attack.len() + self.decay.len() + self.release.len()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_has_expected_total_length() {
+        let total = Envelope::new(10, 10, 1.0, 10).len();
+        assert_eq! (30, total)
+    }
+}
diff --git a/klangfarbrs/src/lib.rs b/klangfarbrs/src/lib.rs
index a96393f..087cbd7 100644
--- a/klangfarbrs/src/lib.rs
+++ b/klangfarbrs/src/lib.rs
@@ -15,6 +15,8 @@ use gdnative::core_types::TypedArray;
 mod osc;
 use osc::{Osc};
 
+mod adsr;
+
 /// Aliasing some types to distinguish various audio properties.
 type Sample = f32;
 type SamplesPerSecond = f32;
-- 
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