From 6c297fab1ef9fc4bb5fe79f3aafd710187a03d43 Mon Sep 17 00:00:00 2001
From: Scott Allen <saydisp-git@yahoo.ca>
Date: Mon, 6 Feb 2017 16:03:15 -0500
Subject: [PATCH] Add nextFrameDEV() function for checking CPU load

---
 keywords.txt     |  1 +
 src/Arduboy2.cpp | 12 ++++++++++++
 src/Arduboy2.h   | 29 ++++++++++++++++++++++++++++-
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/keywords.txt b/keywords.txt
index 866dc2a..28442b8 100644
--- a/keywords.txt
+++ b/keywords.txt
@@ -57,6 +57,7 @@ invert	KEYWORD2
 justPressed	KEYWORD2
 justReleased	KEYWORD2
 nextFrame	KEYWORD2
+nextFrameDEV	KEYWORD2
 notPressed	KEYWORD2
 off	KEYWORD2
 on	KEYWORD2
diff --git a/src/Arduboy2.cpp b/src/Arduboy2.cpp
index 9b5c5e5..e3666bb 100644
--- a/src/Arduboy2.cpp
+++ b/src/Arduboy2.cpp
@@ -169,6 +169,18 @@ bool Arduboy2Base::nextFrame()
   return post_render;
 }
 
+bool Arduboy2Base::nextFrameDEV() {
+  bool ret = nextFrame();
+
+  if (ret) {
+    if (lastFrameDurationMs > eachFrameMillis)
+      TXLED1;
+    else
+      TXLED0;
+  }
+  return ret;
+}
+
 int Arduboy2Base::cpuLoad()
 {
   return lastFrameDurationMs*100 / eachFrameMillis;
diff --git a/src/Arduboy2.h b/src/Arduboy2.h
index 61740a3..1ef35a2 100644
--- a/src/Arduboy2.h
+++ b/src/Arduboy2.h
@@ -613,10 +613,37 @@ class Arduboy2Base : public Arduboy2Core
    * }
    * \endcode
    *
-   * \see setFrameRate()
+   * \see setFrameRate() nextFrameDEV()
    */
   bool nextFrame();
 
+  /** \brief
+   * Indicate that it's time to render the next frame, and visually indicate
+   * if the code is running slower than the desired frame rate.
+   * **FOR USE DURING DEVELOPMENT**
+   *
+   * \return `true` if it's time for the next frame.
+   *
+   * \details
+   * This function is intended to be used in place of `nextFrame()` during the
+   * development of a sketch. It does the same thing as `nextFrame()` but
+   * additionally will light the yellow TX LED (at the bottom, to the left
+   * of the USB connector) whenever a frame takes longer to generate than the
+   * time allotted per frame, as determined by the `setFrameRate()` function.
+   *
+   * Therefore, whenever the TX LED comes on (while not communicating over
+   * USB), it indicates that the sketch is running slower than the desired
+   * rate set by `setFrameRate()`. In this case the developer may wish to set
+   * a slower frame rate, or reduce or optimize the code for such frames.
+   *
+   * \note
+   * Once a sketch is ready for release, it would be expected that
+   * `nextFrameDEV()` calls be restored to `nextFrame()`.
+   *
+   * \see nextFrame() cpuLoad() setFrameRate()
+   */
+  bool nextFrameDEV();
+
   /** \brief
    * Indicate if the specified number of frames has elapsed.
    *