migen/genlib/divider.py

   1 from migen.fhdl.structure import *
   2
   3 class Divider:
   4         def __init__(self, w):
   5                 self.w = w
   6
   7                 self.start_i = Signal()
   8                 self.dividend_i = Signal(w)
   9                 self.divisor_i = Signal(w)
  10                 self.ready_o = Signal()
  11                 self.quotient_o = Signal(w)
  12                 self.remainder_o = Signal(w)
  13
  14         def get_fragment(self):
  15                 w = self.w
  16
  17                 qr = Signal(2*w)
  18                 counter = Signal(max=w+1)
  19                 divisor_r = Signal(w)
  20                 diff = Signal(w+1)
  21
  22                 comb = [
  23                         self.quotient_o.eq(qr[:w]),
  24                         self.remainder_o.eq(qr[w:]),
  25                         self.ready_o.eq(counter == 0),
  26                         diff.eq(self.remainder_o - divisor_r)
  27                 ]
  28                 sync = [
  29                         If(self.start_i,
  30                                 counter.eq(w),
  31                                 qr.eq(self.dividend_i),
  32                                 divisor_r.eq(self.divisor_i)
  33                         ).Elif(~self.ready_o,
  34                                         If(diff[w],
  35                                                 qr.eq(Cat(0, qr[:2*w-1]))
  36                                         ).Else(
  37                                                 qr.eq(Cat(1, qr[:w-1], diff[:w]))
  38                                         ),
  39                                         counter.eq(counter - 1)
  40                         )
  41                 ]
  42                 return Fragment(comb, sync)