feat(isource): add support for ngspice current sources (#453)

tools/ngspice/src/blocks.rs

@@ -81,3 +81,43 @@ impl Schematic<Ngspice> for DcVsource {
         Ok(())
     }
 }
+
+/// A current source.
+#[derive(Serialize, Deserialize, Debug, Copy, Clone, Hash, PartialEq, Eq, Block)]
+#[substrate(io = "TwoTerminalIo")]
+pub enum Isource {
+    /// A dc current source.
+    Dc(Decimal),
+    /// A pulse current source.
+    Pulse(Pulse),
+}
+
+impl Isource {
+    /// Creates a new DC current source.
+    pub fn dc(value: Decimal) -> Self {
+        Self::Dc(value)
+    }
+
+    /// Creates a new pulse current source.
+    pub fn pulse(value: Pulse) -> Self {
+        Self::Pulse(value)
+    }
+}
+
+impl ExportsNestedData for Isource {
+    type NestedData = ();
+}
+
+impl Schematic<Ngspice> for Isource {
+    fn schematic(
+        &self,
+        io: &<<Self as Block>::Io as HardwareType>::Bundle,
+        cell: &mut CellBuilder<Ngspice>,
+    ) -> substrate::error::Result<Self::NestedData> {
+        let mut prim = PrimitiveBinding::new(Primitive::Isource(*self));
+        prim.connect("P", io.p);
+        prim.connect("N", io.n);
+        cell.set_primitive(prim);
+        Ok(())
+    }
+}

tools/ngspice/src/lib.rs

@@ -11,6 +11,7 @@ use std::sync::Arc;
 use crate::blocks::Vsource;
 use crate::tran::Tran;
 use arcstr::ArcStr;
+use blocks::Isource;
 use cache::error::TryInnerError;
 use cache::CacheableWithState;
 use error::*;
@@ -45,13 +46,16 @@ pub enum Primitive {
     Spice(spice::Primitive),
     /// A voltage source with ports "1" and "2".
     Vsource(Vsource),
+    /// A current source with ports "1" and "2".
+    Isource(Isource),
 }
 
 impl Primitive {
     fn ports(&self) -> Vec<ArcStr> {
         match self {
             Primitive::Spice(prim) => prim.ports(),
             Primitive::Vsource(_) => vec!["1".into(), "2".into()],
+            Primitive::Isource(_) => vec!["1".into(), "2".into()],
         }
     }
 }
@@ -753,6 +757,35 @@ impl HasSpiceLikeNetlist for Ngspice {
                 }
                 Ok(name)
             }
+            Primitive::Isource(isource) => {
+                let name = arcstr::format!("I{}", name);
+                write!(out, "{}", name)?;
+                for port in ["P", "N"] {
+                    for part in connections.remove(port).unwrap() {
+                        write!(out, " {}", part)?;
+                    }
+                }
+                match isource {
+                    Isource::Dc(dc) => {
+                        write!(out, " DC {}", dc)?;
+                    }
+                    Isource::Pulse(pulse) => {
+                        write!(
+                            out,
+                            " PULSE({} {} {} {} {} {} {} {})",
+                            pulse.val0,
+                            pulse.val1,
+                            pulse.delay.unwrap_or_default(),
+                            pulse.rise.unwrap_or_default(),
+                            pulse.fall.unwrap_or_default(),
+                            pulse.width.unwrap_or_default(),
+                            pulse.period.unwrap_or_default(),
+                            pulse.num_pulses.unwrap_or_default(),
+                        )?;
+                    }
+                }
+                Ok(name)
+            }
         }
     }
 }