Gear program state

The program is the main unit of the Gear component. Program code is stored as an immutable WASM blob. Each program has a fixed amount of memory which persists between messagehandling (so-called static area).

The minimum structure of the Gear program is this:

#![no_std]

use gstd::msg;

#[no_mangle]
pub unsafe extern "C" fn handle() {
    msg::reply(b"Hello world!", 0).expect("Error in sending reply");
}

#[no_mangle]
pub unsafe extern "C" fn init() {}

Optional init() function is called only once during program initialization and handles the incoming init payload if any.

The handle() function (also optional) will be called every time the program receives an incoming message. In this case, the payload will be processed.