liteeth/mac/core/depacketizer.py

   1 import math
   2
   3 from liteeth.common import *
   4
   5 def _decode_header(h_dict, h_signal, obj):
   6         r = []
   7         for k, v in sorted(h_dict.items()):
   8                 start = v.byte*8+v.offset
   9                 end = start+v.width
  10                 r.append(getattr(obj, k).eq(h_signal[start:end]))
  11         return r
  12
  13 class LiteEthMACDepacketizer(Module):
  14         def __init__(self):
  15                 self.sink = sink = Sink(eth_mac_description(8))
  16                 self.source = source = Source(eth_phy_description(8))
  17                 ###
  18                 shift = Signal()
  19                 header = Signal(mac_header_length*8)
  20                 counter = Counter(max=mac_header_length)
  21                 self.submodules += counter
  22
  23                 fsm = FSM(reset_state="IDLE")
  24                 self.submodules += fsm
  25
  26                 fsm.act("IDLE",
  27                         sink.ack.eq(1),
  28                         counter.reset.eq(1),
  29                         If(sink.stb,
  30                                 shift.eq(1),
  31                                 NextState("RECEIVE_HEADER")
  32                         )
  33                 )
  34                 fsm.act("RECEIVE_HEADER",
  35                         sink.ack.eq(1),
  36                         If(sink.stb,
  37                                 counter.ce.eq(1),
  38                                 shift.eq(1),
  39                                 If(counter.value == mac_header_length-2,
  40                                         NextState("COPY")
  41                                 )
  42                         )
  43                 )
  44                 self.sync += \
  45                         If(fsm.before_entering("COPY"),
  46                                 source.sop.eq(1)
  47                         ).Elif(source.stb & source.ack,
  48                                 source.sop.eq(0)
  49                         )
  50                 self.comb += [
  51                         source.sop.eq(sop),
  52                         source.eop.eq(sink.eop),
  53                         source.data.eq(sink.data),
  54                         source.error.eq(sink.error),
  55                         _decode_header(mac_header, header, source)
  56                 ]
  57                 fsm.act("COPY",
  58                         sink.ack.eq(source.ack),
  59                         source.stb.eq(sink.stb),
  60                         If(source.stb &  source.ack & source.eop,
  61                                 NextState("IDLE")
  62                         )
  63                 )