From 00c336c255ca94a1d52d927ad4ea3e105d0fb12c Mon Sep 17 00:00:00 2001
From: TomAwezome <sonidd1@yahoo.com>
Date: Fri, 8 Jul 2022 04:49:34 -0400
Subject: [PATCH] Implement software loopback for PCNet driver.

---
 src/Home/Net/Drivers/PCNet.ZC | 14 +++++++++-----
 src/Home/Net/Protocols/ARP.ZC |  4 +++-
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/Home/Net/Drivers/PCNet.ZC b/src/Home/Net/Drivers/PCNet.ZC
index 65826a15..3cf9f465 100755
--- a/src/Home/Net/Drivers/PCNet.ZC
+++ b/src/Home/Net/Drivers/PCNet.ZC
@@ -501,12 +501,21 @@ I64 PCNetTransmitPacketAllocate(U8 **packet_buffer_out, I64 length)
 	return de_index;
 }
 
+U8 *EthernetMACGet()
+{
+	return pcnet.mac_address;
+}
+
 U0 PCNetTransmitPacketFinish(I64 de_index)
 {/* Release ownership of the packet to the PCNet card
 	by setting the OWN bit to 1. */ 
 
 	CPCNetDescriptorEntry *entry = &pcnet.tx_de_buffer[de_index * sizeof(CPCNetDescriptorEntry)];
 
+	// check the TX packet MAC against local MAC, if they match: software loopback the TX packet to RX NetQueue
+	if (!MemCompare(EthernetMACGet(), pcnet.tx_buffer_addr + de_index * ETHERNET_FRAME_SIZE, 6))
+		NetQueuePush(pcnet.tx_buffer_addr + de_index * ETHERNET_FRAME_SIZE, U16_MAX - (entry->status1 & 0xFFFF) + 1);
+
 	Bts(&entry->status1, PCNET_DESCRIPTORf_OWN);
 	NetLog("PCNET FINISH TX PACKET: TX DE index: %X, OWN bit of entry at entry: %b.",
 				de_index, Bt(&entry->status1, PCNET_DESCRIPTORf_OWN));
@@ -742,11 +751,6 @@ I64 EthernetFrameAllocate(U8 **packet_buffer_out,
 	return de_index;
 }
 
-U8 *EthernetMACGet()
-{
-	return pcnet.mac_address;
-}
-
 U0 NetStop()
 { // Halt network activity by setting STOP bit on Status CSR.
 	U32 csr = PCNetCSRRead(PCNET_CSR_CTRLSTATUS);
diff --git a/src/Home/Net/Protocols/ARP.ZC b/src/Home/Net/Protocols/ARP.ZC
index 1a80cfb7..347b470c 100755
--- a/src/Home/Net/Protocols/ARP.ZC
+++ b/src/Home/Net/Protocols/ARP.ZC
@@ -127,9 +127,11 @@ CARPHash *ARPCachePut(U32 ip_address, U8 *mac_address)
 }
 
 U0 ARPLocalIPV4Set(U32 ip_address)
-{ // takes in little endian IP, stores into globals as Big Endian
+{ // takes in little endian IP, stores into arp_globals as Big Endian and into ARP cache as Little Endian
 	arp_globals.local_ipv4 = EndianU32(ip_address);
 
+	ARPCachePut(ip_address, EthernetMACGet);
+
 	ARPSend(ARP_REPLY,
 			ethernet_globals.ethernet_broadcast,
 			EthernetMACGet,