src/soc/fu/alu/input_stage.py

   1 # This stage is intended to adjust the input data before sending it to
   2 # the actual ALU. Things like handling inverting the input, xer_ca
   3 # generation for subtraction, and handling of immediates should happen
   4 # in the base class (CommonInputStage.elaborate).
   5 from soc.fu.common_input_stage import CommonInputStage
   6 from soc.fu.alu.pipe_data import ALUInputData
   7
   8
   9 class ALUInputStage(CommonInputStage):
  10     def __init__(self, pspec):
  11         super().__init__(pspec, "input")
  12
  13     def ispec(self):
  14         return ALUInputData(self.pspec)
  15
  16     def ospec(self):
  17         return ALUInputData(self.pspec)
  18
  19     def elaborate(self, platform):
  20         m = super().elaborate(platform) # covers A-invert, carry, and SO.
  21         comb = m.d.comb
  22         ctx = self.i.ctx
  23
  24         # operand b
  25         comb += self.o.b.eq(self.i.b)
  26
  27         return m