From c0b9a8011e5f09063f577d968db9c415a4460a8c Mon Sep 17 00:00:00 2001
From: Martin Teichmann <martin.teichmann@gmail.com>
Date: Mon, 31 Jul 2023 18:15:07 +0100
Subject: [PATCH] factor out a SterilePacket for better testability
---
ebpfcat/ebpfcat.py | 36 +++++++++++++++++++++++++-----------
ebpfcat/ethercat_test.py | 19 ++++++++++++++++++-
2 files changed, 43 insertions(+), 12 deletions(-)
diff --git a/ebpfcat/ebpfcat.py b/ebpfcat/ebpfcat.py
index 6108600..c54c441 100644
--- a/ebpfcat/ebpfcat.py
+++ b/ebpfcat/ebpfcat.py
@@ -264,9 +264,8 @@ class EBPFTerminal(Terminal):
self.position, self.pdo_in_off)
if readwrite and self.pdo_out_sz:
bases[2] = packet.size + packet.DATAGRAM_HEADER
- packet.on_the_fly.append((packet.size, ECCmd.FPWR))
- packet.append(ECCmd.FPWR, b"\0" * self.pdo_out_sz, 0,
- self.position, self.pdo_out_off)
+ packet.append_writer(ECCmd.FPWR, b"\0" * self.pdo_out_sz, 0,
+ self.position, self.pdo_out_off)
return bases
def update(self, data):
@@ -376,6 +375,26 @@ class FastEtherCat(SimpleEtherCat):
v.cancel()
+class SterilePacket(Packet):
+ """a sterile packet has all its sets exchanges by NOPs"""
+ def __init__(self):
+ super().__init__()
+ self.on_the_fly = [] # list of sterilized positions
+
+ def append_writer(self, cmd, *args):
+ self.on_the_fly.append((self.size, cmd))
+ super().append(cmd, *args)
+
+ def sterile(self, index):
+ ret = bytearray(self.assemble(index))
+ for pos, cmd in self.on_the_fly:
+ ret[pos] = ECCmd.NOP.value
+ return ret
+
+ def activate(self, ebpf):
+ for pos, cmd in self.on_the_fly:
+ ebpf.pB[pos + self.ETHERNET_HEADER] = cmd.value
+
class SyncGroupBase:
missed_counter = 0
@@ -413,8 +432,7 @@ class SyncGroupBase:
data = self.update_devices(data)
def allocate(self):
- self.packet = Packet()
- self.packet.on_the_fly = []
+ self.packet = SterilePacket()
self.terminals = {t: t.allocate(self.packet, rw)
for t, rw in self.terminals.items()}
@@ -450,18 +468,14 @@ class FastSyncGroup(SyncGroupBase, XDP):
def program(self):
with self.packetSize >= self.packet.size + Packet.ETHERNET_HEADER as p:
- for pos, cmd in self.packet.on_the_fly:
- p.pB[pos + Packet.ETHERNET_HEADER] = cmd.value
+ self.packet.activate(p)
for dev in self.devices:
dev.program()
self.exit(XDPExitCode.TX)
async def run(self):
with self.ec.register_sync_group(self) as self.packet_index:
- self.asm_packet = bytearray(
- self.packet.assemble(self.packet_index))
- for pos, cmd in self.packet.on_the_fly:
- self.asm_packet[pos] = ECCmd.NOP.value
+ self.asm_packet = self.packet.sterile(self.packet_index)
# prime the pump: two packets to get things going
self.ec.send_packet(self.asm_packet)
self.ec.send_packet(self.asm_packet)
diff --git a/ebpfcat/ethercat_test.py b/ebpfcat/ethercat_test.py
index 79fe8fe..d3f1a40 100644
--- a/ebpfcat/ethercat_test.py
+++ b/ebpfcat/ethercat_test.py
@@ -28,7 +28,7 @@ from .terminals import EL4104, EL3164, EK1814, Skip
from .ethercat import ECCmd, Terminal
from .ebpfcat import (
FastSyncGroup, SyncGroup, TerminalVar, Device, EBPFTerminal, PacketDesc,
- EtherCatBase)
+ EtherCatBase, SterilePacket)
from .ebpf import Instruction, Opcode as O
@@ -395,5 +395,22 @@ class Tests(TestCase):
self.assertEqual(sg.opcodes, [])
+class UnitTests(TestCase):
+ def test_sterile(self):
+ p = SterilePacket()
+ p.append(ECCmd.LRD, b"asdf", 0x33, 0x654321)
+ p.append_writer(ECCmd.FPRD, b"fdsa", 0x44, 0x55, 0x66)
+ self.assertEqual(p.assemble(0x77),
+ H("2e10"
+ "0000770000000280000000000000"
+ "0a332143650004800000617364660000"
+ "04445500660004000000666473610000"))
+ self.assertEqual(p.sterile(0x77),
+ H("2e10"
+ "0000770000000280000000000000"
+ "0a332143650004800000617364660000"
+ "00445500660004000000666473610000"))
+ self.assertEqual(p.on_the_fly, [(32, ECCmd.FPRD)])
+
if __name__ == "__main__":
main()
--
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