TLB/src/LFSR.py

   1 from nmigen import Module, Signal
   2 from nmigen.cli import main
   3
   4 size = 11
   5
   6 class LFSR:
   7     def __init__(self):
   8
   9         # Output
  10         self.enable = Signal(1)
  11         self.o = Signal(size)
  12
  13     def elaborate(self, platform=None):
  14         m = Module()
  15
  16         for i in range(size):
  17             with m.If(self.enable):
  18                 if i == 0:
  19                     zero = self.o[0]
  20                     one = self.o[1]
  21                     m.d.sync += self.o[0].eq(zero ^ one)
  22                 if i == 3:
  23                     zero = self.o[0]
  24                     three = self.o[4]
  25                     m.d.sync += self.o[3].eq(zero ^ three)
  26                 else:
  27                     prev = self.o[(i + 1) % size]
  28                     m.d.sync += self.o[i].eq(prev)
  29         return m
  30