Add slack time scheduling, redid earliest deadline, added max-fan-out and hybrid scheduler, also added example

Also added a couple of tests to reach full test coverage for all core operations.

Closes: #285 (closed) #284 (closed) #281 (closed)

Branched from !469 (merged) so merge that first, I can then rebase if you want to.

b_asic/core_operations.py

@@ -1102,6 +1102,7 @@ class MAD(AbstractOperation):
 class MADS(AbstractOperation):
     __slots__ = (
         "_is_add",
+        "_override_zero_on_src0",
         "_src0",
         "_src1",
         "_src2",
@@ -1111,6 +1112,7 @@ class MADS(AbstractOperation):
         "_execution_time",
     )
     _is_add: Optional[bool]
+    _override_zero_on_src0: Optional[bool]
     _src0: Optional[SignalSourceProvider]
     _src1: Optional[SignalSourceProvider]
     _src2: Optional[SignalSourceProvider]
@@ -1124,6 +1126,7 @@ class MADS(AbstractOperation):
     def __init__(
         self,
         is_add: Optional[bool] = True,
+        override_zero_on_src0: Optional[bool] = False,
         src0: Optional[SignalSourceProvider] = None,
         src1: Optional[SignalSourceProvider] = None,
         src2: Optional[SignalSourceProvider] = None,
@@ -1143,13 +1146,23 @@ class MADS(AbstractOperation):
             execution_time=execution_time,
         )
         self.set_param("is_add", is_add)
+        self.set_param("override_zero_on_src0", override_zero_on_src0)
 
     @classmethod
     def type_name(cls) -> TypeName:
         return TypeName("mads")
 
     def evaluate(self, a, b, c):
-        return a + b * c if self.is_add else a - b * c
+        if self.is_add:
+            if self.override_zero_on_src0:
+                return b * c
+            else:
+                return a + b * c
+        else:
+            if self.override_zero_on_src0:
+                return -b * c
+            else:
+                return a - b * c
 
     @property
     def is_add(self) -> bool:
@@ -1161,11 +1174,21 @@ class MADS(AbstractOperation):
         """Set if operation is an addition."""
         self.set_param("is_add", is_add)
 
+    @property
+    def override_zero_on_src0(self) -> bool:
+        """Get if operation is overriding a zero on port src0."""
+        return self.param("override_zero_on_src0")
+
+    @override_zero_on_src0.setter
+    def override_zero_on_src0(self, override_zero_on_src0: bool) -> None:
+        """Set if operation is overriding a zero on port src0."""
+        self.set_param("override_zero_on_src0", override_zero_on_src0)
+
     @property
     def is_linear(self) -> bool:
         return (
-            self.input(0).connected_source.operation.is_constant
-            or self.input(1).connected_source.operation.is_constant
+            self.input(1).connected_source.operation.is_constant
+            or self.input(2).connected_source.operation.is_constant
         )
 
     def swap_io(self) -> None:
@@ -1598,6 +1621,51 @@ class Shift(AbstractOperation):
         self.set_param("value", value)
 
 
+class DontCare(AbstractOperation):
+    r"""
+    Dont-care operation
+
+    Used for ignoring the input to another operation and thus avoiding dangling input nodes.
+
+    Parameters
+    ----------
+    name : Name, optional
+        Operation name.
+
+    """
+
+    __slots__ = "_name"
+    _name: Name
+
+    is_linear = True
+
+    def __init__(self, name: Name = ""):
+        """Construct a DontCare operation."""
+        super().__init__(
+            input_count=0,
+            output_count=1,
+            name=name,
+            latency_offsets={"out0": 0},
+        )
+
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return TypeName("dontcare")
+
+    def evaluate(self):
+        return 0
+
+    @property
+    def latency(self) -> int:
+        return self.latency_offsets["out0"]
+
+    def __repr__(self) -> str:
+        return "DontCare()"
+
+    def __str__(self) -> str:
+        return "dontcare"
+
+
 class Sink(AbstractOperation):
     r"""
     Sink operation.