From 7732e0d23cff4504333fba213bf79035cdcc9dc6 Mon Sep 17 00:00:00 2001
From: rowanG077 <goemansrowan@gmail.com>
Date: Sun, 16 Jul 2023 23:56:40 +0200
Subject: [PATCH] core/ip.py: Add gateway support

---
 liteeth/core/__init__.py | 12 ++++++++++
 liteeth/core/ip.py       | 47 ++++++++++++++++++++++++++++++++++++----
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/liteeth/core/__init__.py b/liteeth/core/__init__.py
index 4eca8008..819d0953 100644
--- a/liteeth/core/__init__.py
+++ b/liteeth/core/__init__.py
@@ -19,6 +19,9 @@ def __init__(self, phy, mac_address, ip_address, clk_freq, dw=8,
         with_icmp         = True,
         with_ip_broadcast = True,
         with_sys_datapath = False,
+        gateway           = None,
+        netaddress        = None,
+        netmask           = None,
         tx_cdc_depth      = 32,
         tx_cdc_buffered   = True,
         rx_cdc_depth      = 32,
@@ -60,6 +63,9 @@ def __init__(self, phy, mac_address, ip_address, clk_freq, dw=8,
             ip_address     = ip_address,
             arp_table      = self.arp.table,
             with_broadcast = with_ip_broadcast,
+            gateway        = gateway,
+            netaddress     = netaddress,
+            netmask        = netmask,
             dw             = dw,
         )
         # ICMP (Optional).
@@ -78,6 +84,9 @@ def __init__(self, phy, mac_address, ip_address, clk_freq, dw=8,
         with_icmp         = True,
         with_ip_broadcast = True,
         with_sys_datapath = False,
+        gateway           = None,
+        netaddress        = None,
+        netmask           = None,
         tx_cdc_depth      = 32,
         tx_cdc_buffered   = True,
         rx_cdc_depth      = 32,
@@ -98,6 +107,9 @@ def __init__(self, phy, mac_address, ip_address, clk_freq, dw=8,
             dw                = dw,
             with_ip_broadcast = with_ip_broadcast,
             with_sys_datapath = with_sys_datapath,
+            gateway           = gateway,
+            netaddress        = netaddress,
+            netmask           = netmask,
             tx_cdc_depth      = tx_cdc_depth,
             tx_cdc_buffered   = tx_cdc_buffered,
             rx_cdc_depth      = rx_cdc_depth,
diff --git a/liteeth/core/ip.py b/liteeth/core/ip.py
index 84e8e280..6ecee475 100644
--- a/liteeth/core/ip.py
+++ b/liteeth/core/ip.py
@@ -93,8 +93,21 @@ def __init__(self, dw=8):
         )
 
 
-class LiteEthIPTX(LiteXModule):
-    def __init__(self, mac_address, ip_address, arp_table, dw=8):
+class LiteEthIPTX(Module):
+    def __init__(self, mac_address, ip_address, arp_table,
+        gateway = None,
+        netaddress = None,
+        netmask = None,
+        dw=8
+    ):
+        # Must all be either set or not
+        assert (gateway is None) == (netaddress is None) == (netmask is None)
+
+        if gateway is not None:
+            gateway = convert_ip(gateway)
+            netaddress = convert_ip(netaddress)
+            netmask = convert_ip(netmask)
+
         self.sink   = sink   = stream.Endpoint(eth_ipv4_user_description(dw))
         self.source = source = stream.Endpoint(eth_mac_description(dw))
         self.target_unreachable = Signal()
@@ -148,7 +161,19 @@ def __init__(self, mac_address, ip_address, arp_table, dw=8):
                 )
             )
         )
-        self.comb += arp_table.request.ip_address.eq(sink.ip_address)
+
+        if gateway is not None:
+            in_subnet = Signal(1, reset_less=True)
+
+            self.sync += in_subnet.eq((sink.ip_address & netmask) == netaddress)
+            self.comb += If(in_subnet,
+                arp_table.request.ip_address.eq(sink.ip_address)
+            ).Else(
+                arp_table.request.ip_address.eq(gateway)
+            )
+        else:
+            self.comb += arp_table.request.ip_address.eq(sink.ip_address)
+
         fsm.act("SEND_MAC_ADDRESS_REQUEST",
             arp_table.request.valid.eq(1),
             If(arp_table.request.valid & arp_table.request.ready,
@@ -258,7 +283,21 @@ def __init__(self, mac_address, ip_address, with_broadcast=True, dw=8):
 # IP -----------------------------------------------------------------------------------------------
 
 class LiteEthIP(LiteXModule):
-    def __init__(self, mac, mac_address, ip_address, arp_table, with_broadcast=True, dw=8):
+    def __init__(self, mac, mac_address, ip_address, arp_table, dw=8,
+        gateway = None,
+        netaddress = None,
+        netmask = None,
+        with_broadcast=True
+    ):
+        self.submodules.tx = tx = LiteEthIPTX(
+            mac_address,
+            ip_address,
+            arp_table,
+            gateway=gateway,
+            netaddress=netaddress,
+            netmask=netmask,
+            dw=dw
+        )
         self.tx = tx = LiteEthIPTX(mac_address, ip_address, arp_table, dw=dw)
         self.rx = rx = LiteEthIPRX(mac_address, ip_address, with_broadcast, dw=dw)
         mac_port = mac.crossbar.get_port(ethernet_type_ip, dw)