src/experiment/alu_hier.py

   1 from nmigen import Elaboratable, Signal, Module
   2 from nmigen.cli import main
   3
   4
   5 class Adder(Elaboratable):
   6     def __init__(self, width):
   7         self.a   = Signal(width)
   8         self.b   = Signal(width)
   9         self.o   = Signal(width)
  10
  11     def elaborate(self, platform):
  12         m = Module()
  13         m.d.comb += self.o.eq(self.a + self.b)
  14         return m
  15
  16
  17 class Subtractor(Elaboratable):
  18     def __init__(self, width):
  19         self.a   = Signal(width)
  20         self.b   = Signal(width)
  21         self.o   = Signal(width)
  22
  23     def elaborate(self, platform):
  24         m = Module()
  25         m.d.comb += self.o.eq(self.a - self.b)
  26         return m
  27
  28
  29 class ALU(Elaboratable):
  30     def __init__(self, width):
  31         self.op  = Signal()
  32         self.a   = Signal(width)
  33         self.b   = Signal(width)
  34         self.o   = Signal(width)
  35
  36         self.add = Adder(width)
  37         self.sub = Subtractor(width)
  38
  39     def elaborate(self, platform):
  40         m = Module()
  41         m.submodules.add = self.add
  42         m.submodules.sub = self.sub
  43         m.d.comb += [
  44             self.add.a.eq(self.a),
  45             self.sub.a.eq(self.a),
  46             self.add.b.eq(self.b),
  47             self.sub.b.eq(self.b),
  48         ]
  49         with m.If(self.op):
  50             m.d.comb += self.o.eq(self.sub.o)
  51         with m.Else():
  52             m.d.comb += self.o.eq(self.add.o)
  53         return m
  54
  55
  56 if __name__ == "__main__":
  57     alu = ALU(width=16)
  58     main(alu, ports=[alu.op, alu.a, alu.b, alu.o])