EventResponder, MillisTimer, yield

teensy4/EventResponder.cpp

 	enableInterrupts(irq);
 }
 
-void pendablesrvreq_isr(void)
+extern "C" void pendablesrvreq_isr(void)
 {
 	EventResponder::runFromInterrupt();
 }
 
 // TODO: this doesn't work for IMXRT - no longer using predefined names
 extern "C" volatile uint32_t systick_millis_count;
-void systick_isr(void)
+extern "C" void systick_isr(void)
 {
 	systick_millis_count++;
 	MillisTimer::runFromTimer();

teensy4/delay.c

 // hide an undocumented divide-by-240 circuit in the hardware?
 #define SYSTICK_EXT_FREQ 100000
 
+#if 0
+// moved to EventResponder.cpp
 void systick_isr(void)
 {
 	systick_millis_count++;
 	//delayMicroseconds(1);
 	//digitalWriteFast(12, LOW);
 }
+#endif
 
 #if 0
 void millis_init(void)
 }
 #endif
 
-void yield(void)
+/*void yield(void)
 {
 
-}
+}*/
 
 void delay(uint32_t msec)
 {

teensy4/startup.c

 static void memory_clear(uint32_t *dest, uint32_t *dest_end);
 static void configure_systick(void);
 extern void systick_isr(void);
+extern void pendablesrvreq_isr(void);
 void configure_cache(void);
 void unused_interrupt_vector(void);
 void usb_pll_start();
 
 static void configure_systick(void)
 {
+	_VectorsRam[14] = pendablesrvreq_isr;
 	_VectorsRam[15] = systick_isr;
 	SYST_RVR = (SYSTICK_EXT_FREQ / 1000) - 1;
 	SYST_CVR = 0;

teensy4/yield.cpp

+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <Arduino.h>
+#include "EventResponder.h"
+
+void yield(void) __attribute__ ((weak));
+void yield(void)
+{
+	static uint8_t running=0;
+
+	if (running) return; // TODO: does this need to be atomic?
+	running = 1;
+#if 0
+	// TODO: all serialEvent to use EventResponder
+	if (Serial.available()) serialEvent();
+	if (Serial1.available()) serialEvent1();
+	if (Serial2.available()) serialEvent2();
+	if (Serial3.available()) serialEvent3();
+	if (Serial4.available()) serialEvent4();
+	if (Serial5.available()) serialEvent5();
+	if (Serial6.available()) serialEvent6();
+#endif
+	running = 0;
+	EventResponder::runFromYield();
+};