src/ieee754/add/concurrentunit.py

   1 # IEEE Floating Point Adder (Single Precision)
   2 # Copyright (C) Jonathan P Dawson 2013
   3 # 2013-12-12
   4
   5 from math import log
   6 from nmigen import Module
   7 from nmigen.cli import main, verilog
   8
   9 from nmutil.singlepipe import PassThroughStage
  10 from nmutil.multipipe import CombMuxOutPipe
  11 from nmutil.multipipe import PriorityCombMuxInPipe
  12
  13
  14 def num_bits(n):
  15     return int(log(n) / log(2))
  16
  17 class FPADDInMuxPipe(PriorityCombMuxInPipe):
  18     def __init__(self, num_rows, iospecfn):
  19         self.num_rows = num_rows
  20         stage = PassThroughStage(iospecfn)
  21         PriorityCombMuxInPipe.__init__(self, stage, p_len=self.num_rows)
  22
  23
  24 class FPADDMuxOutPipe(CombMuxOutPipe):
  25     def __init__(self, num_rows, iospecfn):
  26         self.num_rows = num_rows
  27         stage = PassThroughStage(iospecfn)
  28         CombMuxOutPipe.__init__(self, stage, n_len=self.num_rows)
  29
  30
  31 class ReservationStations:
  32     """ Reservation-Station pipeline
  33
  34         Input: num_rows - number of input and output Reservation Stations
  35
  36         Requires: the addition of an "alu" object, an i_specfn and an o_specfn
  37
  38         * fan-in on inputs (an array of FPADDBaseData: a,b,mid)
  39         * ALU pipeline
  40         * fan-out on outputs (an array of FPPackData: z,mid)
  41
  42         Fan-in and Fan-out are combinatorial.
  43     """
  44     def __init__(self, num_rows):
  45         self.num_rows = num_rows
  46         self.inpipe = FPADDInMuxPipe(num_rows, self.i_specfn)   # fan-in
  47         self.outpipe = FPADDMuxOutPipe(num_rows, self.o_specfn) # fan-out
  48
  49         self.p = self.inpipe.p  # kinda annoying,
  50         self.n = self.outpipe.n # use pipe in/out as this class in/out
  51         self._ports = self.inpipe.ports() + self.outpipe.ports()
  52
  53     def elaborate(self, platform):
  54         m = Module()
  55         m.submodules.inpipe = self.inpipe
  56         m.submodules.alu = self.alu
  57         m.submodules.outpipe = self.outpipe
  58
  59         m.d.comb += self.inpipe.n.connect_to_next(self.alu.p)
  60         m.d.comb += self.alu.connect_to_next(self.outpipe)
  61
  62         return m
  63
  64     def ports(self):
  65         return self._ports
  66
  67