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 FPNumBaseRecord, FPNumBase, FPRoundingMode
   9 from ieee754.fpcommon.roundz import FPRoundData
  10 from ieee754.fpcommon.packdata import FPPackData
  11
  12
  13 class FPPackMod(PipeModBase):
  14
  15     def __init__(self, pspec):
  16         super().__init__(pspec, "pack")
  17
  18     def ispec(self):
  19         return FPRoundData(self.pspec)
  20
  21     def ospec(self):
  22         return FPPackData(self.pspec)
  23
  24     def elaborate(self, platform):
  25         m = Module()
  26         comb = m.d.comb
  27
  28         z = FPNumBaseRecord(self.pspec.width, False, name="z")
  29         m.submodules.pack_in_z = in_z = FPNumBase(self.i.z)
  30         overflow_array = FPRoundingMode.make_array(
  31             lambda rm: rm.overflow_rounds_to_inf(self.i.z.s))
  32         overflow_rounds_to_inf = Signal()
  33         m.d.comb += overflow_rounds_to_inf.eq(overflow_array[self.i.rm])
  34
  35         with m.If(~self.i.out_do_z):
  36             with m.If(in_z.is_overflowed):
  37                 with m.If(overflow_rounds_to_inf):
  38                     comb += z.inf(self.i.z.s)
  39                 with m.Else():
  40                     comb += z.max_normal(self.i.z.s)
  41             with m.Else():
  42                 comb += z.create(self.i.z.s, self.i.z.e, self.i.z.m)
  43         with m.Else():
  44             comb += z.v.eq(self.i.oz)
  45
  46         comb += self.o.ctx.eq(self.i.ctx)
  47         comb += self.o.z.eq(z.v)
  48
  49         return m