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-rw-r--r--hdl/lib/shift_reg.py82
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