src/ieee754/cordic/sin_cos_pipe_stage.py

   1 from nmigen import Module, Signal, Cat, Mux
   2 from nmutil.pipemodbase import PipeModBase
   3 from ieee754.cordic.pipe_data import CordicData
   4 import math
   5
   6
   7 class CordicStage(PipeModBase):
   8     def __init__(self, pspec, stagenum):
   9         super().__init__(pspec, "cordicstage%d" % stagenum)
  10         self.stagenum = stagenum
  11
  12     def ispec(self):
  13         return CordicData(self.pspec, False)
  14
  15     def ospec(self):
  16         return CordicData(self.pspec, False)
  17
  18     def elaborate(self, platform):
  19         m = Module()
  20         comb = m.d.comb
  21
  22         dx = Signal(self.i.x.shape())
  23         dy = Signal(self.i.y.shape())
  24         dz = Signal(self.i.z.shape())
  25         angle = int(round(self.pspec.M *
  26                           math.atan(2**(-self.stagenum))))
  27
  28         comb += dx.eq(self.i.y >> self.stagenum)
  29         comb += dy.eq(self.i.x >> self.stagenum)
  30         comb += dz.eq(angle)
  31
  32         with m.If(self.i.z >= 0):
  33             comb += self.o.x.eq(self.i.x - dx)
  34             comb += self.o.y.eq(self.i.y + dy)
  35             comb += self.o.z.eq(self.i.z - dz)
  36         with m.Else():
  37             comb += self.o.x.eq(self.i.x + dx)
  38             comb += self.o.y.eq(self.i.y - dy)
  39             comb += self.o.z.eq(self.i.z + dz)
  40
  41         return m