src/ieee754/part_cmp/reorder_results.py

   1 # gt_combiner returns results that are in the wrong order from how
   2 # they need to be. Specifically, if the partition gates are open, the
   3 # bits need to be reversed through the width of the partition. This
   4 # module does that
   5 from nmigen import Signal, Module, Elaboratable, Mux
   6
   7
   8 class ReorderResults(Elaboratable):
   9     def __init__(self, width):
  10         self.width = width
  11         self.results_in = Signal(width, reset_less=True)
  12         self.gates = Signal(width-1, reset_less=True)
  13
  14         self.output = Signal(width, reset_less=True)
  15
  16     def elaborate(self, platform):
  17         m = Module()
  18         comb = m.d.comb
  19         width = self.width
  20
  21         current_result = self.results_in[-1]
  22
  23         for i in range(width-2, -1, -1):  # counts down from width-1 to 0
  24             cur = Signal()
  25             comb += cur.eq(current_result)
  26             comb += self.output[i+1].eq(cur)
  27             current_result = Mux(self.gates[i], self.results_in[i], cur)
  28
  29             comb += self.output[0].eq(current_result)
  30         return m