src/add/pipeline_example.py

   1 """ Example 5: Making use of PyRTL and Introspection. """
   2
   3 from nmigen import Module, Signal
   4 from nmigen.cli import main, verilog
   5
   6
   7 from pipeline import SimplePipeline, ObjectProxy
   8
   9
  10 class SimplePipelineExample(SimplePipeline):
  11     """ A very simple pipeline to show how registers are inferred. """
  12
  13     def __init__(self, pipe):
  14         SimplePipeline.__init__(self, pipe)
  15         self._loopback = Signal(4)
  16         self._setup()
  17
  18     def stage0(self):
  19         self.n = ~self._loopback
  20
  21     def stage1(self):
  22         self.n = self.n + 2
  23
  24     def stage2(self):
  25         localv = Signal(4)
  26         self._pipe.comb += localv.eq(2)
  27         self.n = self.n << localv
  28
  29     def stage3(self):
  30         self.n = ~self.n
  31
  32     def stage4(self):
  33         self._pipe.sync += self._loopback.eq(self.n + 3)
  34
  35
  36 class ObjectBasedPipelineExample(SimplePipeline):
  37     """ A very simple pipeline to show how registers are inferred. """
  38
  39     def __init__(self, pipe):
  40         ObjectBasedPipeline.__init__(self, pipe)
  41         self._loopback = Signal(4)
  42         o = ObjectProxy(pipe)
  43         o.a = Signal(4)
  44         o.b = Signal(4)
  45         self._obj = o
  46         self._setup()
  47
  48     def stage0(self):
  49         self.n = ~self._loopback
  50         self.o = self._obj
  51
  52     def stage1(self):
  53         self.n = self.n + self.o.a
  54         o = ObjectProxy(self._pipe)
  55         o.a = self.n
  56         o.b = self.o.b
  57         self.o = o
  58
  59     def stage2(self):
  60         localv = Signal(4)
  61         self._pipe.comb += localv.eq(2)
  62         self.n = self.n << localv
  63         o = ObjectProxy(self._pipe)
  64         o.b = self.n + self.o.a + self.o.b
  65         self.o = o
  66
  67     def stage3(self):
  68         self.n = ~self.n
  69         self.o = self.o
  70         self.o.b = self.o.b + self.n
  71
  72     def stage4(self):
  73         self._pipe.sync += self._loopback.eq(self.n + 3 + self.o.b)
  74
  75
  76 class PipeModule:
  77
  78     def __init__(self):
  79         self.m = Module()
  80         self.p = ObjectBasedPipelineExample(self.m.d)
  81
  82     def get_fragment(self, platform=None):
  83         return self.m
  84
  85 if __name__ == "__main__":
  86     example = PipeModule()
  87     main(example, ports=[
  88                     example.p._loopback,
  89         ])
  90
  91     #print(verilog.convert(example, ports=[
  92     #           example.p._loopback,
  93     #         ]))