src/ieee754/fpcommon/roundz.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 fpbase import FPNumBase
   9 from fpbase import FPState
  10 from .postnormalise import FPNorm1Data
  11
  12
  13 class FPRoundData:
  14
  15     def __init__(self, width, id_wid):
  16         self.z = FPNumBase(width, False)
  17         self.out_do_z = Signal(reset_less=True)
  18         self.oz = Signal(width, reset_less=True)
  19         self.mid = Signal(id_wid, reset_less=True)
  20
  21     def eq(self, i):
  22         return [self.z.eq(i.z), self.out_do_z.eq(i.out_do_z), self.oz.eq(i.oz),
  23                 self.mid.eq(i.mid)]
  24
  25
  26 class FPRoundMod(Elaboratable):
  27
  28     def __init__(self, width, id_wid):
  29         self.width = width
  30         self.id_wid = id_wid
  31         self.i = self.ispec()
  32         self.out_z = self.ospec()
  33
  34     def ispec(self):
  35         return FPNorm1Data(self.width, self.id_wid)
  36
  37     def ospec(self):
  38         return FPRoundData(self.width, self.id_wid)
  39
  40     def process(self, i):
  41         return self.out_z
  42
  43     def setup(self, m, i):
  44         m.submodules.roundz = self
  45         m.d.comb += self.i.eq(i)
  46
  47     def elaborate(self, platform):
  48         m = Module()
  49         m.d.comb += self.out_z.eq(self.i) # copies mid, z, out_do_z
  50         with m.If(~self.i.out_do_z):
  51             with m.If(self.i.roundz):
  52                 m.d.comb += self.out_z.z.m.eq(self.i.z.m + 1) # mantissa up
  53                 with m.If(self.i.z.m == self.i.z.m1s): # all 1s
  54                     m.d.comb += self.out_z.z.e.eq(self.i.z.e + 1) # exponent up
  55
  56         return m
  57
  58
  59 class FPRound(FPState):
  60
  61     def __init__(self, width, id_wid):
  62         FPState.__init__(self, "round")
  63         self.mod = FPRoundMod(width)
  64         self.out_z = self.ospec()
  65
  66     def ispec(self):
  67         return self.mod.ispec()
  68
  69     def ospec(self):
  70         return self.mod.ospec()
  71
  72     def setup(self, m, i):
  73         """ links module to inputs and outputs
  74         """
  75         self.mod.setup(m, i)
  76
  77         self.idsync(m)
  78         m.d.sync += self.out_z.eq(self.mod.out_z)
  79         m.d.sync += self.out_z.mid.eq(self.mod.o.mid)
  80
  81     def action(self, m):
  82         m.next = "corrections"