Add skeleton for the radio mesh simulator

test/mesh/simulator.h

@@ -0,0 +1,67 @@
+// Copyright (c) 2026 Cesanta Software Limited
+// All rights reserved
+
+#pragma once
+
+#define MG_ENABLE_TCPIP 1
+
+#include "l2_802154.h"
+#include "l2_mesh.h"
+#include "mongoose.h"
+#include "star.h"
+
+// A position in metres
+struct pos {
+  double x, y, z;  // Coordinates
+};
+
+// A bridge: forwards frames between the LAN and the radio, no IP stack
+struct bridge {
+  struct bridge *next;     // Next in simulator::bridges
+  struct pos pos;          // Where it is
+  struct mg_tcpip_if lif;  // LAN side: LAN driver, gets every LAN frame
+  struct mg_tcpip_if rif;  // Radio side: radio driver, gets every frame
+};
+
+// A radio node: Mongoose on a radio interface
+struct radio_node {
+  struct radio_node *next;  // Next in simulator::nodes
+  struct pos pos;           // Where it is
+  struct mg_mgr mgr;        // Mongoose event manager
+  struct mg_tcpip_if rif;   // Radio interface. rif.ip from DHCP, 0: none yet
+};
+
+struct simulator;
+
+// LAN station: a DHCP server, 10.0.0.1. Gives each client an address made
+// from its MAC, see node_ip()
+struct lan_dhcp_server {
+  struct mg_tcpip_if lif;  // Its LAN interface, no Mongoose on it
+};
+
+// LAN station: the test station, 10.0.0.2, a Mongoose instance. Waits for
+// the mesh to settle, then sends GET / to each node
+struct lan_tester {
+  struct mg_mgr mgr;        // Its Mongoose
+  struct mg_tcpip_if lif;   // Its LAN interface
+  uint64_t wait;            // Mesh settle time: start requests then, us
+  struct radio_node *next;  // Node to request next, NULL: all done
+  struct mg_connection *c;  // Request on the way, NULL: none
+  uint64_t start;           // When it started, us
+  int ok, failed;           // Requests done, by result
+  double min, max, sum;     // Times of successful requests, ms
+};
+
+// Simulator state
+struct simulator {
+  struct pos area;              // A box: all positions inside
+  struct bridge *bridges;       // Bridges, a list
+  struct radio_node *nodes;     // Radio nodes, a list
+  int num_bridges, num_nodes;   // How many
+  uint64_t now;                 // Virtual time, us since the start
+  uint64_t duration;            // Run this long, us
+  uint32_t last_mac;            // Low 3 bytes of the last MAC given
+  int request_timeout_ms;       // A request that takes longer failed
+  struct lan_dhcp_server dhcp;  // DHCP server on the LAN
+  struct lan_tester tester;     // Test station on the LAN
+};