src/ieee754/fpcommon/pack.py

   1 # IEEE Floating Point Adder (Single Precision)
   2 # Copyright (C) Jonathan P Dawson 2013
   3 # 2013-12-12
   4
   5 from nmigen import Module, Signal
   6
   7 from nmutil.pipemodbase import PipeModBase
   8 from ieee754.fpcommon.fpbase import FPFormat, FPNumBaseRecord, FPNumBase, \
   9     FPRoundingMode
  10 from ieee754.fpcommon.roundz import FPRoundData
  11 from ieee754.fpcommon.packdata import FPPackData
  12
  13
  14 class FPPackMod(PipeModBase):
  15
  16     def __init__(self, pspec):
  17         super().__init__(pspec, "pack")
  18
  19     def ispec(self):
  20         return FPRoundData(self.pspec)
  21
  22     def ospec(self):
  23         return FPPackData(self.pspec)
  24
  25     def elaborate(self, platform):
  26         m = Module()
  27         comb = m.d.comb
  28
  29         z = FPNumBaseRecord(m_extra=False, name="z",
  30                             fpformat=FPFormat.from_pspec(self.pspec))
  31         m.submodules.pack_in_z = in_z = FPNumBase(self.i.z)
  32         overflow_array = FPRoundingMode.make_array(
  33             lambda rm: rm.overflow_rounds_to_inf(self.i.z.s))
  34         overflow_rounds_to_inf = Signal()
  35         m.d.comb += overflow_rounds_to_inf.eq(overflow_array[self.i.rm])
  36
  37         with m.If(~self.i.out_do_z):
  38             with m.If(in_z.is_overflowed):
  39                 with m.If(overflow_rounds_to_inf):
  40                     comb += z.inf(self.i.z.s)
  41                 with m.Else():
  42                     comb += z.max_normal(self.i.z.s)
  43             with m.Else():
  44                 comb += z.create(self.i.z.s, self.i.z.e, self.i.z.m)
  45         with m.Else():
  46             comb += z.v.eq(self.i.oz)
  47
  48         comb += self.o.ctx.eq(self.i.ctx)
  49         comb += self.o.z.eq(z.v)
  50
  51         return m