src/ieee754/cordic/sin_cos_pipe_stage.py

   1 from nmigen import Module, Signal
   2 from nmutil.pipemodbase import PipeModBase
   3 from ieee754.cordic.pipe_data import CordicData, CordicInitialData
   4 import math
   5
   6
   7 class CordicInitialStage(PipeModBase):
   8     def __init__(self, pspec):
   9         super().__init__(pspec, "cordicinit")
  10
  11     def ispec(self):
  12         return CordicInitialData(self.pspec)
  13
  14     def ospec(self):
  15         return CordicData(self.pspec)
  16
  17     def elaborate(self, platform):
  18         m = Module()
  19         comb = m.d.comb
  20
  21         An = 1.0
  22         for i in range(self.pspec.iterations):
  23             An *= math.sqrt(1 + 2**(-2*i))
  24         X0 = int(round(self.pspec.M*1/An))
  25
  26         comb += self.o.x.eq(X0)
  27         comb += self.o.y.eq(0)
  28         comb += self.o.z.eq(self.i.z0)
  29         return m
  30
  31
  32 class CordicStage(PipeModBase):
  33     def __init__(self, pspec, stagenum):
  34         super().__init__(pspec, "cordicstage%d" % stagenum)
  35         self.stagenum = stagenum
  36
  37     def ispec(self):
  38         return CordicData(self.pspec)
  39
  40     def ospec(self):
  41         return CordicData(self.pspec)
  42
  43     def elaborate(self, platform):
  44         m = Module()
  45         comb = m.d.comb
  46
  47         dx = Signal(self.i.x.shape())
  48         dy = Signal(self.i.y.shape())
  49         dz = Signal(self.i.z.shape())
  50         angle = int(round(self.pspec.M *
  51                           math.atan(2**(-self.stagenum))))
  52
  53         comb += dx.eq(self.i.y >> self.stagenum)
  54         comb += dy.eq(self.i.x >> self.stagenum)
  55         comb += dz.eq(angle)
  56
  57         with m.If(self.i.z >= 0):
  58             comb += self.o.x.eq(self.i.x - dx)
  59             comb += self.o.y.eq(self.i.y + dy)
  60             comb += self.o.z.eq(self.i.z - dz)
  61         with m.Else():
  62             comb += self.o.x.eq(self.i.x + dx)
  63             comb += self.o.y.eq(self.i.y - dy)
  64             comb += self.o.z.eq(self.i.z + dz)
  65
  66         return m