src/ieee754/cordic/renormalize.py

   1 from nmigen import Module, Signal, Mux, Elaboratable, unsigned
   2 from nmutil.pipemodbase import PipeModBase
   3 from nmutil.clz import CLZ
   4 from ieee754.cordic.pipe_data import CordicData, CordicOutputData
   5 from ieee754.fpcommon.fpbase import FPNumBaseRecord
   6
   7
   8 class Norm(Elaboratable):
   9     def __init__(self, pspec):
  10         self.sig_in = Signal(range(-pspec.M, pspec.M+1))
  11
  12         self.sig_out = Signal(pspec.width)
  13         self.width = pspec.width
  14
  15     def elaborate(self, platform):
  16         m = Module()
  17         comb = m.d.comb
  18
  19         numrec = FPNumBaseRecord(self.width, False)
  20
  21         sign = Signal(1)
  22         comb += sign.eq(self.sig_in[-1])
  23
  24         absv = Signal.like(self.sig_in)
  25         comb += absv.eq(Mux(sign, -self.sig_in, self.sig_in))
  26
  27         m.submodules.clzx = clz = CLZ(self.sig_in.width)
  28
  29         count = Signal.like(clz.lz)
  30
  31         comb += clz.sig_in.eq(absv)
  32         comb += count.eq(clz.lz)
  33
  34         normalized = Signal(unsigned(self.sig_in.width))
  35
  36         comb += normalized.eq(absv << (count-1))
  37
  38         comb += numrec.m.eq(normalized[-(numrec.m_width+1):-1])
  39         comb += numrec.s.eq(sign)
  40         comb += numrec.e.eq(-count+1)
  41
  42         comb += self.sig_out.eq(numrec.create2(numrec.s, numrec.e, numrec.m))
  43         return m
  44
  45 class CordicRenormalize(PipeModBase):
  46     def __init__(self, pspec):
  47         super().__init__(pspec, "cordicrenorm")
  48
  49     def ispec(self):
  50         return CordicData(self.pspec)
  51
  52     def ospec(self):
  53         return CordicOutputData(self.pspec)
  54
  55     def elaborate(self, platform):
  56         m = Module()
  57         comb = m.d.comb
  58
  59         m.submodules.normx = normx = Norm(self.pspec)
  60         m.submodules.normy = normy = Norm(self.pspec)
  61
  62         comb += [
  63             normx.sig_in.eq(self.i.x),
  64             normy.sig_in.eq(self.i.y),
  65         ]
  66
  67         comb += self.o.x.eq(normx.sig_out)
  68         comb += self.o.y.eq(normy.sig_out)
  69
  70         comb += self.o.ctx.eq(self.i.ctx)
  71         return m