From e59158e006f6940e7f3a789688cbbc3a6d12d476 Mon Sep 17 00:00:00 2001
From: logicog <git@logicog.de>
Date: Mon, 12 Jan 2026 14:34:36 +0100
Subject: [PATCH] Add backend support for L2 entries in web

---
 httpd/httpd.c     |  3 ++
 httpd/page_impl.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++
 httpd/page_impl.h |  1 +
 3 files changed, 100 insertions(+)

diff --git a/httpd/httpd.c b/httpd/httpd.c
index b50a3e7..bbb0a29 100644
--- a/httpd/httpd.c
+++ b/httpd/httpd.c
@@ -573,6 +573,9 @@ void httpd_appcall(void)
 				send_counters(q[20]-'0');
 			} else if (is_word(q, "/eee.json")) {
 				send_eee();
+			} else if (is_word(q, "/l2.json")) {
+				parse_short(q + 13); // e.g.: /l2.json?idx=10
+				send_l2(short_parsed);
 			} else if (is_word(q, "/mirror.json")) {
 				send_mirror();
 			} else if (is_word(q, "/mtu.json")) {
diff --git a/httpd/page_impl.c b/httpd/page_impl.c
index 871818d..8727d3a 100644
--- a/httpd/page_impl.c
+++ b/httpd/page_impl.c
@@ -16,6 +16,8 @@
 // #define DEBUG
 #include "debug.h"
 
+#define L2_MAX_TRANSFER 2
+
 #pragma codeseg BANK1
 #pragma constseg BANK1
 
@@ -283,6 +285,100 @@ void send_counters(char port)
 }
 
 
+void send_l2(uint16_t idx)
+{
+	slen = strtox(outbuf, HTTP_RESPONCE_JSON);
+	dbg_string("sending L2\n");  // TODO: Remove
+	print_short(idx);
+	__xdata uint8_t entries_left = L2_MAX_TRANSFER;
+
+	do {
+		reg_read_m(RTL837X_TBL_CTRL);
+	} while (sfr_data[3] & 0x01);
+
+	/* The L2 table in the ASIC can hold up to 4096 (0x1000) entries, which
+	 * are accessed using an index. The index is the hash of the MAC address
+	 * and forwarding ID (basically VID). The hash-table is 4-way associative,
+	 * i.e. for a given hash value, 4 entries with that same hash can be stored
+	 * (i.e. the hash points to a bucket with up to 4 entries).
+	 * When the table or a hash bucket is full, further entries will lead to
+	 * L2 flooding.
+	 * To find all entries, we start with entry-index 0 and iteratively search for
+	 * the next entry (with the next higher index), until we arrive again at the first
+	 * entry. The indices are sorted, so if an entry has a smaller index than
+	 * the previous one, we know that we have wrapped around the entire table.
+	 */
+	__xdata uint16_t entry = idx;
+	__xdata uint16_t first_entry = 0xffff; // An illegal entry index
+	char_to_html('[');
+	while (1) {
+		entries_left--;
+		uint8_t port = 0;
+		reg_read_m(RTL837x_TBL_DATA_0);
+		REG_WRITE(RTL837x_TBL_DATA_0, sfr_data[0], sfr_data[1],sfr_data[2] | 0xc0, sfr_data[3]);
+
+		REG_WRITE(RTL837X_TBL_CTRL, entry >> 8, entry, TBL_L2_UNICAST, 0x1);
+		do {
+			reg_read_m(RTL837X_TBL_CTRL);
+		} while (sfr_data[3] & 0x1);
+
+		reg_read_m(RTL837x_L2_DATA_OUT_B);
+		if ((sfr_data[0] & 0x20)) {	// Check entry is valid
+			// MAC
+			slen += strtox(outbuf + slen, "{\"mac\":\"");
+			byte_to_html(sfr_data[2]); char_to_html(':');
+			byte_to_html(sfr_data[3]); char_to_html(':');
+			port = (sfr_data[0] >> 6) & 0x3;
+			reg_read_m(RTL837x_L2_DATA_OUT_A);
+			byte_to_html(sfr_data[0]); char_to_html(':');
+			byte_to_html(sfr_data[1]); char_to_html(':');
+			byte_to_html(sfr_data[2]); char_to_html(':');
+			byte_to_html(sfr_data[3]);
+
+			// VLAN
+			slen += strtox(outbuf + slen, "\", \"vlan\":\"");
+			reg_read_m(RTL837x_L2_DATA_OUT_B);
+			charhex_to_html(sfr_data[0] & 0x0f);
+			byte_to_html(sfr_data[1]);
+
+			// type
+			reg_read_m(RTL837x_L2_DATA_OUT_C);
+			if (sfr_data[2] & 0x1)
+				slen += strtox(outbuf + slen, "\",\"type\":\"s\", \"port\":");
+			else
+				slen += strtox(outbuf + slen, "\",\"type\":\"l\", \"port\":");
+
+			port |= (sfr_data[3] & 0x3) << 2;
+			itoa_html(port);
+
+			// Index
+			reg_read_m(RTL837x_TBL_DATA_0);
+			entry = (((uint16_t)sfr_data[2] & 0x0f) << 8) | sfr_data[3];
+			slen += strtox(outbuf + slen, ",\"idx\":\"");
+			byte_to_html(entry >> 8);
+			byte_to_html(entry);
+			char_to_html('"');
+			char_to_html('}');
+			entry += 1; // We want the next entry following after the current entry
+		} else {
+			reg_read_m(RTL837x_TBL_DATA_0);
+			entry = (((uint16_t)sfr_data[2] & 0x0f) << 8) | sfr_data[3] + 1;
+		}
+		if (first_entry == 0xffff) {
+			char_to_html(',');
+			first_entry = entry;
+		} else {
+			if (first_entry == entry || !entries_left) {
+				char_to_html(']');
+				break;
+			} else {
+				char_to_html(',');
+			}
+		}
+	}
+}
+
+
 void send_mirror(void)
 {
 	dbg_string("send_mirror called\n");
diff --git a/httpd/page_impl.h b/httpd/page_impl.h
index 064a9df..a67d503 100644
--- a/httpd/page_impl.h
+++ b/httpd/page_impl.h
@@ -6,6 +6,7 @@ void send_status(void);
 void send_vlan(uint16_t vlan);
 void send_basic_info(void);
 void send_eee(void);
+void send_l2(uint16_t idx);
 void send_mirror(void);
 void send_mtu(void);
 void send_config(void);