src/ieee754/fpdiv/divstages.py

   1 """IEEE754 Floating Point pipelined Divider
   2
   3 Relevant bugreport: http://bugs.libre-riscv.org/show_bug.cgi?id=99
   4
   5 """
   6
   7 from nmigen import Module
   8 from nmigen.cli import main, verilog
   9
  10 from nmutil.singlepipe import (StageChain, SimpleHandshake)
  11
  12 from ieee754.fpcommon.fpbase import FPState
  13 from ieee754.fpcommon.denorm import FPSCData
  14 from ieee754.fpcommon.postcalc import FPAddStage1Data
  15
  16 # TODO: write these
  17 from .div0 import FPDivStage0Mod
  18 from .div1 import FPDivStage1Mod
  19 from .div2 import FPDivStage2Mod
  20
  21
  22 class FPDivStages(FPState, SimpleHandshake):
  23
  24     def __init__(self, width, id_wid):
  25         FPState.__init__(self, "align")
  26         self.width = width
  27         self.id_wid = id_wid
  28         SimpleHandshake.__init__(self, self) # pipeline is its own stage
  29         self.m1o = self.ospec()
  30
  31     def ispec(self):
  32         return FPSCData(self.width, self.id_wid, False)
  33
  34     def ospec(self):
  35         return FPAddStage1Data(self.width, self.id_wid) # AddStage1 ospec
  36
  37     def setup(self, m, i):
  38         """ links module to inputs and outputs
  39         """
  40
  41         # TODO.  clearly, this would be a for-loop, here, creating
  42         # a huge number of stages (if radix-2 is used).  interestingly
  43         # the number of stages will be data-dependent.
  44         divstages = [FPDivStage0Mod(self.width, self.id_wid)]
  45         for i in range(self.width): # XXX TODO: work out actual number needed
  46             divstages.append(FPDivStage1Mod(self.width, self.id_wid))
  47         divstages.append(FPDivStage2Mod(self.width, self.id_wid))
  48
  49         chain = StageChain(divstages)
  50         chain.setup(m, i)
  51
  52         self.o = m1mod.o
  53
  54     def process(self, i):
  55         return self.o
  56
  57     def action(self, m):
  58         m.d.sync += self.m1o.eq(self.process(None))
  59         m.next = "normalise_1"
  60
  61