mac: add padding

diff --git a/liteeth/mac/core/__init__.py b/liteeth/mac/core/__init__.py
index d5bf2f93471392eb54168c414e80cbb6dc7f3ede..34a21ad10076869e21b3fc466b24d2aacd5e8bd6 100644 (file)
--- a/liteeth/mac/core/__init__.py
+++ b/liteeth/mac/core/__init__.py
@@ -1,6 +1,6 @@
 from liteeth.common import *
 from liteeth.generic import *
-from liteeth.mac.core import gap, preamble, crc, last_be
+from liteeth.mac.core import gap, preamble, crc, padding, last_be
 
 class LiteEthMACCore(Module, AutoCSR):
        def __init__(self, phy, dw, endianness="big", with_hw_preamble_crc=True):
@@ -37,6 +37,15 @@ class LiteEthMACCore(Module, AutoCSR):
                        tx_pipeline += [preamble_inserter, crc32_inserter]
                        rx_pipeline += [preamble_checker, crc32_checker]
 
+               # Padding
+               padding_inserter = padding.LiteEthMACPaddingInserter(phy.dw, 60)
+               padding_checker = padding.LiteEthMACPaddingChecker(phy.dw, 60)
+               self.submodules += RenameClockDomains(padding_inserter, "eth_tx")
+               self.submodules += RenameClockDomains(padding_checker, "eth_rx")
+
+               tx_pipeline += [padding_inserter]
+               rx_pipeline += [padding_checker]
+
                # Delimiters
                if dw != 8:
                        tx_last_be = last_be.LiteEthMACTXLastBE(phy.dw)

diff --git a/liteeth/mac/core/padding.py b/liteeth/mac/core/padding.py
new file mode 100644 (file)
index 0000000..12970fe
--- /dev/null
+++ b/liteeth/mac/core/padding.py
@@ -0,0 +1,47 @@
+from liteeth.common import *
+from liteeth.generic import *
+
+class LiteEthMACPaddingInserter(Module):
+       def __init__(self, dw, packet_min_length):
+               self.sink = sink = Sink(eth_phy_description(dw))
+               self.source = source = Source(eth_phy_description(dw))
+               ###
+               packet_min_data = math.ceil(packet_min_length/(dw/8))
+
+               self.submodules.counter = counter = Counter(max=eth_mtu)
+
+               self.submodules.fsm = fsm = FSM(reset_state="COPY")
+               fsm.act("COPY",
+                       counter.reset.eq(sink.stb & sink.sop),
+                       Record.connect(sink, source),
+                       If(sink.stb & sink.ack,
+                               counter.ce.eq(1),
+                               If(sink.eop,
+                                       If(counter.value < (packet_min_data-1),
+                                               source.eop.eq(0),
+                                               NextState("PADDING")
+                                       )
+                               )
+                       )
+               )
+               fsm.act("PADDING",
+                       source.stb.eq(1),
+                       source.eop.eq(counter.value == (packet_min_data-1)),
+                       source.data.eq(0),
+                       If(source.ack,
+                               counter.ce.eq(1),
+                               If(source.eop,
+                                       NextState("COPY")
+                               )
+                       )
+               )
+
+class LiteEthMACPaddingChecker(Module):
+       def __init__(self, dw, packet_min_length):
+               self.sink = sink = Sink(eth_phy_description(dw))
+               self.source = source = Source(eth_phy_description(dw))
+               ###
+               # XXX see if we should drop the packet when
+               # payload size < minimum ethernet payload size
+               self.comb += Record.connect(sink, source)
+