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core/udp: Add dw>8 support to LiteEthUDPRX 

Pass through last_be or create a new one based on the length if needed

Initialize count at dw//8 and don't subtract source_length since it
could lead to underflow for very short packets. In case source.length is
not dw aligned, count will not be equal, so adjust comparison for that.

Crib last_be Case lookup from mac/sram.py
This commit is contained in:
David Sawatzke 2021-12-03 01:49:51 +01:00
parent 7acb2a8c1c
commit 72b1a1f91e
1 changed files with 17 additions and 2 deletions
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19
liteeth/core/udp.py
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@ -180,7 +180,7 @@ class LiteEthUDPRX(Module):
count = Signal(16)
self.submodules.fsm = fsm = FSM(reset_state="IDLE")
fsm.act("IDLE",
NextValue(count, 0),
NextValue(count, dw//8),
If(depacketizer.source.valid,
NextState("DROP"),
If(sink.protocol == udp_protocol,
@ -190,7 +190,22 @@ class LiteEthUDPRX(Module):
)
fsm.act("RECEIVE",
depacketizer.source.connect(source, keep={"valid", "ready"}),
source.last.eq(depacketizer.source.last | (count == (source.length - dw//8))),
source.last.eq(depacketizer.source.last | (count >= source.length)),
If(depacketizer.source.last_be,
source.last_be.eq(depacketizer.source.last_be),
).Elif(
source.last,
Case(source.length & (dw//8 - 1), {
1 : source.last_be.eq(0b00000001),
2 : source.last_be.eq(0b00000010),
3 : source.last_be.eq(0b00000100),
4 : source.last_be.eq(0b00001000),
5 : source.last_be.eq(0b00010000),
6 : source.last_be.eq(0b00100000),
7 : source.last_be.eq(0b01000000),
"default" : source.last_be.eq(2**(dw//8 - 1)),
})
),
If(source.valid & source.ready,
NextValue(count, count + dw//8),
If(depacketizer.source.last,