Draft: Add more WDF adaptors

Closes #257

b_asic/wdf_operations.py

@@ -3,7 +3,7 @@ B-ASIC Core Operations Module.
 
 Contains wave digital filter adaptors.
 """
-from typing import Dict, Optional
+from typing import Dict, Optional, Tuple
 
 from b_asic.graph_component import Name, TypeName
 from b_asic.operation import AbstractOperation
@@ -101,7 +101,7 @@ class SeriesTwoportAdaptor(AbstractOperation):
         latency_offsets: Optional[Dict[str, int]] = None,
         execution_time: Optional[int] = None,
     ):
-        """Construct a SymmetricTwoportAdaptor operation."""
+        """Construct a SeriesTwoportAdaptor operation."""
         super().__init__(
             input_count=2,
             output_count=2,
@@ -144,3 +144,64 @@ class SeriesTwoportAdaptor(AbstractOperation):
         for i, p in enumerate(self._output_ports):
             p._index = i
         self.set_param("value", 2 - self.value)
+
+
+class SeriesThreeportAdaptor(AbstractOperation):
+    r"""
+    Wave digital filter series threeport-adaptor operation.
+
+    .. math::
+        \begin{eqnarray}
+        y_0 & = & x_0 - \text{value}_0\times\left(x_0 + x_1 + x_2\right)\\
+        y_1 & = & x_1 - \text{value}_1\times\left(x_0 + x_1 + x_2\right)\\
+        y_2 & = & x_2 - \left(2 - \text{value}_0 - \text{value}_1\right)\times\left(x_0
+                + x_1 + x_2\right)
+        \end{eqnarray}
+    """
+    is_linear = True
+    is_swappable = True
+
+    def __init__(
+        self,
+        value: Tuple[Num, Num] = (0, 0),
+        src0: Optional[SignalSourceProvider] = None,
+        src1: Optional[SignalSourceProvider] = None,
+        src2: Optional[SignalSourceProvider] = None,
+        name: Name = Name(""),
+        latency: Optional[int] = None,
+        latency_offsets: Optional[Dict[str, int]] = None,
+        execution_time: Optional[int] = None,
+    ):
+        """Construct a SeriesThreeportAdaptor operation."""
+        super().__init__(
+            input_count=3,
+            output_count=3,
+            name=Name(name),
+            input_sources=[src0, src1, src2],
+            latency=latency,
+            latency_offsets=latency_offsets,
+            execution_time=execution_time,
+        )
+        self.value = value
+
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return TypeName("ser3p")
+
+    def evaluate(self, a, b, c):
+        s = a + b + c
+        val0, val1 = self.value
+        return a - val0 * s, b - val1 * s, c - (2 - val0 - val1) * s
+
+    @property
+    def value(self) -> Num:
+        """Get the constant value of this operation."""
+        return self.param("value")
+
+    @value.setter
+    def value(self, value: Num) -> None:
+        """Set the constant value of this operation."""
+        if 0 <= sum(value) <= 2:
+            self.set_param("value", value)
+        else:
+            raise ValueError('sum of value must be between 0 and 2 (inclusive)')