feat: add rust demo

examples/tos_meets_rust/app/src/bridge.rs

@@ -0,0 +1,11 @@
+use cty::*;
+
+/// These glue functions are from tosglue.c
+extern {
+    pub fn rust_print(msg: *const u8);
+    pub fn rust_oled_print(msg: *const u8);
+    pub fn rust_wifi_init() -> i32;
+    pub fn rust_wifi_connect(ssid: *const u8, passwd: *const u8);
+    pub fn rust_sleep(ms: u32);
+    pub fn rust_mqtt_daemon() -> c_void;
+}