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 from nmigen.cli import main, verilog
   7
   8 from nmutil.pipemodbase import PipeModBase
   9 from ieee754.fpcommon.fpbase import FPNumBaseRecord, FPNumBase
  10 from ieee754.fpcommon.roundz import FPRoundData
  11 from ieee754.fpcommon.getop import FPPipeContext
  12
  13
  14 class FPPackData:
  15
  16     def __init__(self, pspec):
  17         width = pspec.width
  18         self.z = Signal(width, reset_less=True)    # result
  19         self.ctx = FPPipeContext(pspec)
  20
  21         # this is complicated: it's a workaround, due to the
  22         # array-indexing not working properly in nmigen.
  23         # self.ports() is used to access the ArrayProxy objects by name,
  24         # however it doesn't work recursively.  the workaround:
  25         # drop the sub-objects into *this* scope and they can be
  26         # accessed / set.  it's horrible.
  27         self.muxid = self.ctx.muxid
  28         self.op = self.ctx.op
  29
  30     def eq(self, i):
  31         return [self.z.eq(i.z), self.ctx.eq(i.ctx)]
  32
  33     def __iter__(self):
  34         yield self.z
  35         yield from self.ctx
  36
  37     def ports(self):
  38         return list(self)
  39
  40
  41 class FPPackMod(PipeModBase):
  42
  43     def __init__(self, pspec):
  44         super().__init__(pspec, "pack")
  45
  46     def ispec(self):
  47         return FPRoundData(self.pspec)
  48
  49     def ospec(self):
  50         return FPPackData(self.pspec)
  51
  52     def elaborate(self, platform):
  53         m = Module()
  54         comb = m.d.comb
  55
  56         z = FPNumBaseRecord(self.pspec.width, False, name="z")
  57         m.submodules.pack_in_z = in_z = FPNumBase(self.i.z)
  58
  59         with m.If(~self.i.out_do_z):
  60             with m.If(in_z.is_overflowed):
  61                 comb += z.inf(self.i.z.s)
  62             with m.Else():
  63                 comb += z.create(self.i.z.s, self.i.z.e, self.i.z.m)
  64         with m.Else():
  65             comb += z.v.eq(self.i.oz)
  66
  67         comb += self.o.ctx.eq(self.i.ctx)
  68         comb += self.o.z.eq(z.v)
  69
  70         return m