1 files changed, 82 insertions, 0 deletions
diff --git a/hdl/lib/shift_reg.py b/hdl/lib/shift_reg.py
new file mode 100644
index 0000000..3fb05c1
--- /dev/null
+++ b/hdl/lib/shift_reg.py
@@ -0,0 +1,82 @@
+from amaranth import *
+from amaranth.sim import Simulator, Settle, Delay
+
+from hdl.utils import cmd
+
+class ShiftReg(Elaboratable):
+    def __init__(self, width):
+        self.name = "shift_reg"
+
+        self.load_val = Signal(width, reset=0, reset_less=True)
+        self.load = Signal()
+        self.reg = Signal(width)
+        self.en = Signal()
+        self.right_left = Signal()
+
+        ports_in = [self.load_val, self.en, self.load, self.right_left]
+        ports_out = [self.reg]
+        self.ports = {'in': ports_in, 'out': ports_out}
+
+    def elaborate(self, platform):
+        m = Module()
+
+        with m.If(self.load):
+            m.d.sync += self.reg.eq(self.load_val)
+        with m.Else():
+            with m.If(self.en):
+                with m.If(self.right_left):
+                    m.d.sync += self.reg.eq(self.reg << 1)
+                with m.Else():
+                    m.d.sync += self.reg.eq(self.reg >> 1)
+
+        return m
+
+def test_shift_reg(filename="out.vcd"):
+    dut = ShiftReg(8)
+
+    def proc1():
+        val = 0xAB
+
+        yield dut.load_val.eq(val)
+        yield dut.en.eq(0)
+        yield dut.load.eq(1)
+        yield
+        yield Settle()
+        yield dut.load.eq(0)
+        yield dut.en.eq(1)   
+
+        for _ in range(9):
+            reg_val = yield dut.reg
+            assert reg_val == val, f"Incorrect shift ---EXPECTED: {hex(val)}   ---GOT: {hex(reg_val)}"
+            val = val >> 1
+            yield
+            yield Settle()
+
+        val = 0xBD
+        yield dut.load_val.eq(val)
+        yield dut.load.eq(1)
+        yield dut.right_left.eq(1)
+        yield
+        yield Settle()
+        yield dut.load.eq(0)
+
+        for _ in range(9):
+            reg_val = yield dut.reg
+            assert reg_val == val, f"Incorrect shift ---EXPECTED: {hex(val)}   ---GOT: {hex(reg_val)}"
+            val = (val << 1) & 0xff
+            yield
+            yield Settle()
+
+
+
+    sim = Simulator(dut)
+    sim.add_clock(1e-6)
+    sim.add_sync_process(proc1)
+    
+    with sim.write_vcd(filename):
+        sim.run()
+
+
+if __name__ == '__main__':
+    shift_reg = ShiftReg(8)
+    cmd(shift_reg, test_shift_reg)
+\ No newline at end of file