Update the demo to fetch JavaScript from the server and run it.

Author: davidchisnall

demos/2024-04-23-cheritech/cheri.js

@@ -0,0 +1,87 @@
+// FFI Imports
+// Each function imported from the host environment needs to be assigned to a
+// global like this and identified by a constant that the resolver in the C/C++
+// code will understand.
+// These constants are defined in the `Exports` enumeration.
+
+
+var FFINumber = 1;
+
+/**
+ * Log function, writes all arguments to the UART.
+ */
+export const print = vmImport(FFINumber++);
+
+/**
+ * led_on(index).
+ *
+ * Turns on the LED at the specified index.
+ */
+export const led_on = vmImport(FFINumber++);
+
+/**
+ * led_off(index).
+ *
+ * Turns off the LED at the specified index.
+ */
+export const led_off = vmImport(FFINumber++);
+
+/**
+ * buttons_read().
+ *
+ * Reads the value of all of the buttons, returning a 4-bit value indicating
+ * the states of all of them.
+ */
+export const buttons_read = vmImport(FFINumber++);
+
+/**
+ * switches_read().
+ *
+ * Reads the value of all of the switches, returning a 4-bit value indicating
+ * the states of all of them.
+ */
+export const switches_read = vmImport(FFINumber++);
+
+
+export const mqtt_publish = vmImport(FFINumber++);
+export const mqtt_subscribe = vmImport(FFINumber++);
+
+/**
+ * led_set(index, state).
+ *
+ * Turns the LED at the specified index on or off depending on whether state is
+ * true or false.
+ */
+export function led_set(index, state)
+{
+	if (state)
+	{
+		led_on(index);
+	}
+	else
+	{
+		led_off(index);
+	}
+}
+
+/**
+ * button_read(index).
+ *
+ * Reads the value of the button at the specified index.
+ */
+export function button_read(index)
+{
+	return (buttons_read() & (1 << index)) !== 0;
+}
+
+
+/**
+ * switch_read(index).
+ *
+ * Reads the value of the switch at the specified index.
+ */
+export function switch_read(index)
+{
+	return (switches_read() & (1 << index)) !== 0;
+}
+