Define ports for a simple sequential Shifter

diff --git a/src/soc/experiment/alu_fsm.py b/src/soc/experiment/alu_fsm.py
index 96290f4e690465f42d94df6b3927eac9931f82cf..f95c865d941345609afdebb9a1bc0896a9ede3ff 100644 (file)
--- a/src/soc/experiment/alu_fsm.py
+++ b/src/soc/experiment/alu_fsm.py
@@ -12,3 +12,73 @@ The basic rules are:
 4) The FSM stays in the Done state while n.ready_i is low, otherwise
    it releases the output data and goes back to the Idle state.
 """
+
+from nmigen import Elaboratable, Signal, Module
+from nmigen.back.pysim import Simulator
+
+
+class Shifter(Elaboratable):
+    """Simple sequential shifter
+
+    Prev port data:
+    * p.data_i.data:  Value to be shifted
+    * p.data_i.shift: Shift amount
+    * p.data_i.dir:   Shift direction
+
+    Next port data:
+    * n.data_o: Shifted value
+    """
+    class PrevData:
+        def __init__(self, width):
+            self.data = Signal(width, name="p_data_i")
+            self.shift = Signal(width, name="p_shift_i")
+            self.dir = Signal(name="p_dir_i")
+
+    class PrevPort:
+        def __init__(self, width):
+            self.data_i = Shifter.PrevData(width)
+            self.valid_i = Signal(name="p_valid_i")
+            self.ready_o = Signal(name="p_ready_o")
+
+    class NextPort:
+        def __init__(self, width):
+            self.data_o = Signal(width, name="n_data_o")
+            self.valid_o = Signal(name="n_valid_o")
+            self.ready_i = Signal(name="n_ready_i")
+
+    def __init__(self, width):
+        self.width = width
+        self.p = self.PrevPort(width)
+        self.n = self.NextPort(width)
+
+    def elaborate(self, platform):
+        m = Module()
+        # TODO: Implement Module
+        return m
+
+    def __iter__(self):
+        yield self.p.data_i.data
+        yield self.p.data_i.shift
+        yield self.p.data_i.dir
+        yield self.p.valid_i
+        yield self.p.ready_o
+        yield self.n.ready_i
+        yield self.n.valid_o
+        yield self.n.data_o
+
+    def ports(self):
+        return list(self)
+
+
+def test_shifter():
+    m = Module()
+    m.submodules.shf = dut = Shifter(8)
+    print("Shifter port names:")
+    for port in dut:
+        print("-", port.name)
+    sim = Simulator(m)
+    # Todo: Implement Simulation
+
+
+if __name__ == "__main__":
+    test_shifter()