pipeline GW: add back crc for handling stream pak

src/gateware/cxp_pipeline.py

@@ -1,6 +1,7 @@
 from migen import *
 from misoc.interconnect.csr import *
 from misoc.interconnect import stream
+from misoc.cores.liteeth_mini.mac.crc import LiteEthMACCRCEngine, LiteEthMACCRCChecker
 
 char_width = 8
 char_layout = [("data", char_width), ("k", char_width//8)]
@@ -448,3 +449,34 @@ class CXP_Trig_Ack_Checker(Module, AutoCSR):
                 )
             )
         )
+
+@ResetInserter()
+@CEInserter()
+class CXPCRC32(Module):
+    # Section 9.2.2.2 (CXP-001-2021)
+    width = 32
+    polynom = 0x04C11DB7
+    seed = 2**width-1
+    check = 0x00000000
+    def __init__(self, data_width):
+        self.data = Signal(data_width)
+        self.value = Signal(self.width)
+        self.error = Signal()
+
+        # # #
+
+        self.submodules.engine = LiteEthMACCRCEngine(data_width, self.width, self.polynom)
+        reg = Signal(self.width, reset=self.seed)
+        self.sync += reg.eq(self.engine.next)
+        self.comb += [
+            self.engine.data.eq(self.data),
+            self.engine.last.eq(reg),
+
+            self.value.eq(reg[::-1]),
+            self.error.eq(self.engine.next != self.check)
+        ]
+
+# For verifying crc in stream data packet
+class CXPCRC32Checker(LiteEthMACCRCChecker):
+    def __init__(self, layout):
+        LiteEthMACCRCChecker.__init__(self, CXPCRC32, layout)