TLB/src/WalkingPriorityEncoder.py

   1 from nmigen import Array, Module, Signal
   2 from nmigen.lib.coding import PriorityEncoder, Decoder
   3
   4 class WalkingPriorityEncoder():
   5
   6     def __init__(self, width):
   7         # Internal
   8         self.current = Signal(width)
   9         self.encoder = PriorityEncoder(width)
  10
  11         # Input
  12         self.write = Signal(1)
  13         self.input = Signal(width)
  14
  15         # Output
  16         self.match = Signal(1)
  17         self.output = Signal(width)
  18
  19     def elaborate(self, platform=None):
  20         m = Module()
  21
  22         m.submodules += self.encoder
  23
  24         with m.If(self.write == 0):
  25             with m.If(self.encoder.n == 0):
  26                 m.d.sync += [
  27                     self.output.eq(self.encoder.o),
  28                     self.match.eq(1)
  29                 ]
  30                 m.d.sync += self.current.eq(self.current ^ \
  31                                             (1 << self.encoder.o))
  32                 m.d.sync += self.encoder.i.eq(self.current ^ \
  33                                               (1 << self.encoder.o))
  34
  35             with m.Else():
  36                 m.d.sync += self.match.eq(0)
  37                 m.d.sync += self.encoder.i.eq(0)
  38
  39         with m.Else():
  40             m.d.sync += self.encoder.i.eq(self.input)
  41             m.d.sync += self.current.eq(self.input)
  42             m.d.sync += self.encoder.i.eq(self.input)
  43             m.d.sync += self.match.eq(0)
  44
  45         return m