Fix #485

This fixes #485.

ChangeLog.md

@@ -16,7 +16,12 @@ These are typically planned for release in a future version (usually the next on
 * Re-add SPI atttach and detach.
 * Add contributed variation on the latch no seq example.
 
+### 1.5.11 (Emergency fix)
+* At some point in the recent past, I must have angered the gods of C, and suddenly millis disabled stopped working - the system would hang (actually, with in-depth investigation, it was shown to be bootlooping - before it called init(), it was calling 0x0000 (a dirty reset) instead of eliding a weakly defined function with nothing in the body except a return, or with an empty body. Why was it doing this? And why only when millis was disabled?). millis disabled is a key piece of core functionality, necessitating an urgent fix. Moving the definitions into main.cpp resolved this issue.
+* Investigaing reported PWM issues.
+
 ## Releases
+
 ### 1.5.10 (Emergency fix)
 * Enhancement/bugfix - add digitalPinToCanon() - given a pin number, it returns port * 8 + bit_position. This is to be used in some other fixes and enhancements.
 * Workaround Arduino CLI regression impacting CI testing.

megaavr/cores/dxcore/Arduino.h

@@ -1185,4 +1185,5 @@ void pinConfigure(const uint8_t digital_pin, const pin_configure_t mode, const M
 // open serial port, if the user tied it to a different port? Or thought they
 // were going to use software serial "like they always did" (*shudder*)
 
+
 #endif

megaavr/cores/dxcore/hooks.c

@@ -16,6 +16,7 @@
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 #include <stdint.h>
+#include <Arduino.h>
 /**
  * Empty yield() hook.
  *
@@ -25,10 +26,7 @@
  * Its defined as a weak symbol and it can be redefined to implement a
  * real cooperative scheduler.
  */
-static void __empty() {
-  // Empty
-}
-void yield(void) __attribute__ ((weak, alias("__empty")));
+void __attribute__((weak)) yield(void)  {return;}
 
 /* Hooks to get in real early. onPreMain runs in init3,
  * (it gets called by _initthreestuff, which is setting IVSEL if we are using a fake bootloader section,
@@ -39,21 +37,21 @@ void yield(void) __attribute__ ((weak, alias("__empty")));
  * even the blocking delays will give correct times. No class constructors have been called, In fact, the previous paragraph is pretty much
  * all that has been done, other than clearing r1 so we can execute compiled C code ()
  */
-void onPreMain() __attribute__((weak, alias("__empty")));
+
+//void __attribute__((weak)) onPreMain() {return;}
 
 /* onBeforeInit() after class constructors but before any hardware is initialized per core settings. */
-void onBeforeInit() __attribute__((weak, alias("__empty")));
+//void __attribute__((weak)) onBeforeInit() {return;}
 
 /* onAfterInit() is called after the init routines, immediately before enabling interrupts. Setup() is called after this.
  * And that's really the main purpose of this function - it gives you a way to tell the initialization routines "Hey, don't enable interrupts yet"
  * You can prevent interrupts from being enabled by returning a non-zero value
  */
-uint8_t onAfterInit() __attribute__((weak));
-uint8_t onAfterInit() {
-  return 0;
-}
+//uint8_t __attribute__((weak)) onAfterInit() {
+//  return 0;
+//}
 
-void initVariant() { }
+//void __attribute__((weak)) initVariant() { }
 /* Weak empty variant initialization function. The purpose is unclear. It sounds like it was intended
  * initialize the variant, and specific variants would have their own implementation. But in practice
  * it seems to be instead used as an initialization callback that libraries can use to run code before

megaavr/cores/dxcore/main.cpp

@@ -7,30 +7,23 @@
 /* Required by some libraries to compile successfully. Even though it's nonsense in Arduino. */
 int atexit(void ( * /*func*/)()) { return 0; }
 
-// these week definitions were moved to hooks.c
-void initVariant() __attribute__((weak));
-/* Weak empty variant initialization function. The purpose is unclear. It sounds like it was intended
- * initialize the variant, and specific variants would have their own implementation. But in practice
- * it seems to be instead used as an initialization callback that libraries can use to run code before
- * setup, like FreeRTOS - it would have been nice if the official API included such a callback. */
-
-
-void __attribute__((weak)) onPreMain();
-//void __attribute__((weak)) onPreMain() {
-  /* Override with any user code that needs to run WAY early, in .init3 */
-//}
-void __attribute__((weak)) onBeforeInit();
-//void __attribute__((weak)) onBeforeInit() {
-  /* Override with any user code that needs to run before init() */
-//}
-uint8_t __attribute__((weak)) onAfterInit();
-//uint8_t __attribute__((weak)) onAfterInit() {
-  /* Override with any user code that needs to run before interrupts are
-   * enabled but after all other core initialization.
-   * return 1 to not enable interrupts) */
-//  return 0;
-//}
+/* What the bloody hell is going on? Why does everything fall down around my ears if disable
+ * millis is set and these functions are located in any other file. What is different?!
+ * It doesn't seem to be recognizing the "default" definition, because it compiles to a call
+ * pointed at 0x0000, which constitues directly requesting a dirty reset, and that is indeed
+ * what you get. And it bootloops very rapidly as a result, because that call haoppens at
+ * OnBeforeInit(). As the name suggests, that's the callback called before init() is called
+ * to set up the hardware */
 
+void __attribute__((weak)) initVariant() {return;} // Reserved for library use.
+void __attribute__((weak)) onPreMain() {return;}   // Called in .init3. Remember to bring your stone tools and loincloth
+// you must survive under the most primitive of conditions. No millis, no delay, F_CPU is defined to a speed other than the
+// frequency it's running at, constructors have not run, etc.
+void __attribute__((weak)) onBeforeInit() {return;} // Called before init. You can step up to maybe the bronze age, but
+// things are still pretty rough, because the init() function has not been called and that sets up the clock, the timers
+// and a wide variety of other things.
+uint8_t __attribute__((weak)) onAfterInit() {return 0;} // Called between init() and the call to sei() to enable interrupts immediately prior to jumping to main.
+// Unlike the others, this one has a return value. If you return a 1, sei() will not be called.
 
 
 #if defined(LOCK_FLMAP)