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, Elaboratable
   6 from nmigen.cli import main, verilog
   7
   8 from ieee754.fpcommon.fpbase import FPNumOut, FPNumBaseRecord, FPNumBase
   9 from ieee754.fpcommon.fpbase import FPState
  10 from .roundz import FPRoundData
  11 from nmutil.singlepipe import Object
  12 from ieee754.fpcommon.getop import FPPipeContext
  13
  14
  15 class FPPackData:
  16
  17     def __init__(self, pspec):
  18         width = pspec['width']
  19         self.z = Signal(width, reset_less=True)    # result
  20         self.ctx = FPPipeContext(pspec)
  21
  22         # this is complicated: it's a workaround, due to the
  23         # array-indexing not working properly in nmigen.
  24         # self.ports() is used to access the ArrayProxy objects by name,
  25         # however it doesn't work recursively.  the workaround:
  26         # drop the sub-objects into *this* scope and they can be
  27         # accessed / set.  it's horrible.
  28         self.muxid = self.ctx.muxid
  29         self.op = self.ctx.op
  30
  31     def eq(self, i):
  32         return [self.z.eq(i.z), self.ctx.eq(i.ctx)]
  33
  34     def __iter__(self):
  35         yield self.z
  36         yield from self.ctx
  37
  38     def ports(self):
  39         return list(self)
  40
  41
  42 class FPPackMod(Elaboratable):
  43
  44     def __init__(self, pspec):
  45         self.pspec = pspec
  46         self.i = self.ispec()
  47         self.o = self.ospec()
  48
  49     def ispec(self):
  50         return FPRoundData(self.pspec)
  51
  52     def ospec(self):
  53         return FPPackData(self.pspec)
  54
  55     def process(self, i):
  56         return self.o
  57
  58     def setup(self, m, in_z):
  59         """ links module to inputs and outputs
  60         """
  61         m.submodules.pack = self
  62         m.d.comb += self.i.eq(in_z)
  63
  64     def elaborate(self, platform):
  65         m = Module()
  66         z = FPNumBaseRecord(self.pspec['width'], False)
  67         m.submodules.pack_in_z = in_z = FPNumBase(self.i.z)
  68         #m.submodules.pack_out_z = out_z = FPNumOut(z)
  69         m.d.comb += self.o.ctx.eq(self.i.ctx)
  70         with m.If(~self.i.out_do_z):
  71             with m.If(in_z.is_overflowed):
  72                 m.d.comb += z.inf(self.i.z.s)
  73             with m.Else():
  74                 m.d.comb += z.create(self.i.z.s, self.i.z.e, self.i.z.m)
  75         with m.Else():
  76             m.d.comb += z.v.eq(self.i.oz)
  77         m.d.comb += self.o.z.eq(z.v)
  78         return m
  79
  80
  81 class FPPack(FPState):
  82
  83     def __init__(self, width, id_wid):
  84         FPState.__init__(self, "pack")
  85         self.mod = FPPackMod(width)
  86         self.out_z = self.ospec()
  87
  88     def ispec(self):
  89         return self.mod.ispec()
  90
  91     def ospec(self):
  92         return self.mod.ospec()
  93
  94     def setup(self, m, in_z):
  95         """ links module to inputs and outputs
  96         """
  97         self.mod.setup(m, in_z)
  98
  99         m.d.sync += self.out_z.v.eq(self.mod.out_z.v)
 100         m.d.sync += self.out_z.ctx.eq(self.mod.o.ctx)
 101
 102     def action(self, m):
 103         m.next = "pack_put_z"