From cc0d44e2534bc553e31f566c10c7858b7a7a2142 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Hru=C5=A1ka?= <ondra@ondrovo.com>
Date: Sun, 4 Jan 2026 21:57:18 +0100
Subject: [PATCH] bess test regs

---
 src/main.c | 61 +++++++++++++++++++++++++-----------------------------
 1 file changed, 28 insertions(+), 33 deletions(-)

diff --git a/src/main.c b/src/main.c
index 1ce35ba..7e98adb 100644
--- a/src/main.c
+++ b/src/main.c
@@ -5,6 +5,9 @@
 
 #include "modbus.h"
 
+#define PORT 5002
+#define MTU_SIZE 1024
+
 ModbusException_t startOfAccess(ModbusSlave_t *ms, ModbusFunction_t fcx, uint8_t slave_id) {
     printf("Start of access: fc%02d, slave %d\n", fcx, slave_id);
     return 0;
@@ -22,45 +25,26 @@ typedef struct {
     bool value;
 } coil_slot_t;
 
+// pattern indicating end of the register array
+#define ENDSLOT {0xffff, 0}
+
 //@formatter:off
 static register_slot_t holdings[] = {
-    {1, 10},
-    {2, 20},
-    {3, 30},
-    {4, 40},
-    {5, 50},
-    {7, 70},
-    {0xffff, 0}
+    {2, 15},
+    ENDSLOT
 };
 
 static register_slot_t inputs[] = {
-    {1, 11},
-    {2, 21},
-    {3, 31},
-    {4, 41},
-    {5, 51},
-    {7, 71},
-    {0xffff, 0}
+    {103, 67},
+    ENDSLOT
 };
 
 static coil_slot_t coils[] = {
-    {1, 1},
-    {2, 0},
-    {3, 1},
-    {4, 0},
-    {5, 1},
-    {7, 1},
-    {0xffff, 0}
+    ENDSLOT
 };
 
 static coil_slot_t discretes[] = {
-    {1, 0},
-    {2, 1},
-    {3, 1},
-    {4, 1},
-    {5, 1},
-    {7, 0},
-    {0xffff, 0}
+    ENDSLOT
 };
 //@formatter:on
 
@@ -184,15 +168,26 @@ int msg_received_fce(int fd, const simple_msg_t *msg) {
     return 0;
 }
 
+// need a wrapper to adapt the return type to atexit()
 void atexitcb() { simple_tcp_server_stop(); }
 
-int main() {
-    // ModbusError_t e = mb_handleRequest(&ms, buf, pldlen, buf2, buflen, &respsize);
-
+int main(int argc, char *argv[]) {
     atexit(atexitcb);
 
-    printf("Starting TCP server\n");
-    simple_tcp_server_start(5002, 1024, msg_received_fce, NULL, NULL);
+    int port = PORT; // default port
+
+    if (argc > 1) {
+        // this is unsafe
+        port = atoi(argv[1]);
+    }
+
+    if (port <= 0 || port > 65535) {
+        printf("Invalid port: %d\n", PORT);
+        return 1;
+    }
+
+    printf("Starting TCP server on port %d\n", port);
+    simple_tcp_server_start(port, MTU_SIZE, msg_received_fce, NULL, NULL);
 
     printf("Thread created, waiting\n");
     while (!simple_tcp_server_ended()) {