src/ieee754/fpmul/align.py

   1 # IEEE Floating Point Multiplier
   2
   3 from nmigen import Module, Signal, Cat, Mux
   4 from nmigen.cli import main, verilog
   5 from math import log
   6
   7 from nmutil.pipemodbase import FPModBase
   8 from ieee754.fpcommon.fpbase import FPNumBase
   9 from ieee754.fpcommon.getop import FPPipeContext
  10 from ieee754.fpcommon.msbhigh import FPMSBHigh
  11 from ieee754.fpcommon.denorm import FPSCData
  12 from ieee754.fpcommon.postcalc import FPAddStage1Data
  13
  14
  15 class FPAlignModSingle(FPModBase):
  16
  17     def __init__(self, pspec, e_extra=False):
  18         self.e_extra = e_extra
  19         super().__init__(pspec, "align")
  20
  21     def ispec(self):
  22         return FPSCData(self.pspec, False)
  23
  24     def ospec(self):
  25         return FPSCData(self.pspec, False)
  26
  27     def elaborate(self, platform):
  28         m = Module()
  29         comb = m.d.comb
  30
  31         self.o.a.m.name = "o_a_m"
  32         self.o.b.m.name = "o_b_m"
  33
  34         m.submodules.norm1_insel_a = insel_a = FPNumBase(self.i.a)
  35         m.submodules.norm1_insel_b = insel_b = FPNumBase(self.i.b)
  36         insel_a.m.name = "i_a_m"
  37         insel_b.m.name = "i_b_m"
  38
  39         mwid = self.o.z.m_width
  40         msb_a = FPMSBHigh(mwid, len(insel_a.e))
  41         msb_b = FPMSBHigh(mwid, len(insel_b.e))
  42         m.submodules.norm_pe_a = msb_a
  43         m.submodules.norm_pe_b = msb_b
  44
  45         # connect to msb_a/b module
  46         comb += msb_a.m_in.eq(insel_a.m)
  47         comb += msb_a.e_in.eq(insel_a.e)
  48         comb += msb_b.m_in.eq(insel_b.m)
  49         comb += msb_b.e_in.eq(insel_b.e)
  50
  51         # copy input to output (overridden below)
  52         comb += self.o.a.eq(insel_a)
  53         comb += self.o.b.eq(insel_b)
  54
  55         # normalisation increase/decrease conditions
  56         decrease_a = Signal(reset_less=True)
  57         decrease_b = Signal(reset_less=True)
  58         comb += decrease_a.eq(insel_a.m_msbzero)
  59         comb += decrease_b.eq(insel_b.m_msbzero)
  60
  61         # ok this is near-identical to FPNorm: use same class (FPMSBHigh)
  62         with m.If(~self.i.out_do_z):
  63             with m.If(decrease_a):
  64                 comb += [
  65                     self.o.a.e.eq(msb_a.e_out),
  66                     self.o.a.m.eq(msb_a.m_out),
  67                 ]
  68             with m.If(decrease_b):
  69                 comb += [
  70                     self.o.b.e.eq(msb_b.e_out),
  71                     self.o.b.m.eq(msb_b.m_out),
  72                 ]
  73
  74         comb += self.o.ctx.eq(self.i.ctx)
  75         comb += self.o.out_do_z.eq(self.i.out_do_z)
  76         comb += self.o.oz.eq(self.i.oz)
  77
  78         return m