From a36dccfad0ecd564c7341db96e821704a9e1097e Mon Sep 17 00:00:00 2001
From: Neil McKechnie <neilmck999@gmail.com>
Date: Tue, 21 Feb 2023 10:55:37 +0000
Subject: [PATCH] Add UserAddin class to facilitate user-written cyclic
 functions.

UserAddin allows a function to be 'plugged in' to the IODevice (HAL) framework and executed cyclically, using just one line of code in the myHal.cpp.  This will facilitate functions for displaying CS state on OLEDs and LCDs, among other things.
---
 IODevice.h | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/IODevice.h b/IODevice.h
index 3ff1dbe..51b5aa0 100644
--- a/IODevice.h
+++ b/IODevice.h
@@ -418,6 +418,55 @@ private:
 
 /////////////////////////////////////////////////////////////////////////////////////////////////////
 
+
+// IODevice framework for invoking user-written functions.
+// To use, define a function that you want to be regularly
+// invoked, and then create an instance of UserAddin.  
+// For example, you can show the status, on screen 3, of the first eight
+// locos in the speed table:
+// 
+// void updateLocoScreen() {
+//   for (int i=0; i<8; i++) {
+//     if (DCC::speedTable[i].loco > 0) {
+//       int speed = DCC::speedTable[i].speedCode;
+//       SCREEN(3, i, F("Loco:%4d %3d %c"), DCC::speedTable[i].loco,
+//         speed & 0x7f, speed & 0x80 ? 'R' : 'F');
+//     }
+//   }
+// }
+//
+// void halSetup() {
+//   ...
+//   UserAddin(updateLocoScreen, 1000);  // Update every 1000ms
+//   ...
+// }
+//
+class UserAddin : public IODevice {
+private:
+  void (*_invokeUserFunction)();
+  int _delay; // milliseconds
+public:
+  UserAddin(void (*func)(), int delay) {
+    _invokeUserFunction = func; 
+    _delay = delay; 
+    addDevice(this); 
+  }
+  // userFunction has no return value, no parameter.  delay is in milliseconds.
+  static void create(void (*userFunction)(), int delay) {
+    new UserAddin(userFunction, delay);
+  }
+protected:
+  void _begin() { _display(); }
+  void _loop(unsigned long currentMicros) override {
+    _invokeUserFunction();
+    // _loop won't be called again until _delay ms have elapsed.
+    delayUntil(currentMicros + _delay * 1000UL);
+  }
+  void _display() override {
+    DIAG(F("UserAddin run every %dms"), _delay);
+  }
+};
+
 #include "IO_MCP23008.h"
 #include "IO_MCP23017.h"
 #include "IO_PCF8574.h"