src/add/fpcommon/denorm.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 from math import log
   8
   9 from fpbase import FPNumIn, FPNumOut, FPNumBase
  10 from fpbase import FPState
  11
  12
  13 class FPSCData:
  14
  15     def __init__(self, width, id_wid):
  16         self.a = FPNumBase(width, True)
  17         self.b = FPNumBase(width, True)
  18         self.z = FPNumOut(width, False)
  19         self.oz = Signal(width, reset_less=True)
  20         self.out_do_z = Signal(reset_less=True)
  21         self.mid = Signal(id_wid, reset_less=True)
  22
  23     def eq(self, i):
  24         return [self.z.eq(i.z), self.out_do_z.eq(i.out_do_z), self.oz.eq(i.oz),
  25                 self.a.eq(i.a), self.b.eq(i.b), self.mid.eq(i.mid)]
  26
  27
  28 class FPAddDeNormMod(FPState):
  29
  30     def __init__(self, width, id_wid):
  31         self.width = width
  32         self.id_wid = id_wid
  33         self.i = self.ispec()
  34         self.o = self.ospec()
  35
  36     def ispec(self):
  37         return FPSCData(self.width, self.id_wid)
  38
  39     def ospec(self):
  40         return FPSCData(self.width, self.id_wid)
  41
  42     def process(self, i):
  43         return self.o
  44
  45     def setup(self, m, i):
  46         """ links module to inputs and outputs
  47         """
  48         m.submodules.denormalise = self
  49         m.d.comb += self.i.eq(i)
  50
  51     def elaborate(self, platform):
  52         m = Module()
  53         m.submodules.denorm_in_a = self.i.a
  54         m.submodules.denorm_in_b = self.i.b
  55         m.submodules.denorm_out_a = self.o.a
  56         m.submodules.denorm_out_b = self.o.b
  57
  58         with m.If(~self.i.out_do_z):
  59             # XXX hmmm, don't like repeating identical code
  60             m.d.comb += self.o.a.eq(self.i.a)
  61             with m.If(self.i.a.exp_n127):
  62                 m.d.comb += self.o.a.e.eq(self.i.a.N126) # limit a exponent
  63             with m.Else():
  64                 m.d.comb += self.o.a.m[-1].eq(1) # set top mantissa bit
  65
  66             m.d.comb += self.o.b.eq(self.i.b)
  67             with m.If(self.i.b.exp_n127):
  68                 m.d.comb += self.o.b.e.eq(self.i.b.N126) # limit a exponent
  69             with m.Else():
  70                 m.d.comb += self.o.b.m[-1].eq(1) # set top mantissa bit
  71
  72         m.d.comb += self.o.mid.eq(self.i.mid)
  73         m.d.comb += self.o.z.eq(self.i.z)
  74         m.d.comb += self.o.out_do_z.eq(self.i.out_do_z)
  75         m.d.comb += self.o.oz.eq(self.i.oz)
  76
  77         return m
  78
  79
  80 class FPAddDeNorm(FPState):
  81
  82     def __init__(self, width, id_wid):
  83         FPState.__init__(self, "denormalise")
  84         self.mod = FPAddDeNormMod(width)
  85         self.out_a = FPNumBase(width)
  86         self.out_b = FPNumBase(width)
  87
  88     def setup(self, m, i):
  89         """ links module to inputs and outputs
  90         """
  91         self.mod.setup(m, i)
  92
  93         m.d.sync += self.out_a.eq(self.mod.out_a)
  94         m.d.sync += self.out_b.eq(self.mod.out_b)
  95
  96     def action(self, m):
  97         # Denormalised Number checks
  98         m.next = "align"
  99
 100