Added general yield()-hook for cooperative scheduling development

build/shared/lib/keywords.txt

@@ -161,6 +161,7 @@ pulseIn	KEYWORD2	PulseIn
 shiftIn	KEYWORD2	ShiftIn
 shiftOut	KEYWORD2	ShiftOut
 tone	KEYWORD2	Tone
+yield	KEYWORD2	Yield
 
 Serial	KEYWORD3	Serial
 Serial1	KEYWORD3	Serial

hardware/arduino/avr/cores/arduino/Arduino.h

@@ -15,6 +15,8 @@
 extern "C"{
 #endif
 
+#define yield()
+
 #define HIGH 0x1
 #define LOW  0x0
 

hardware/arduino/sam/cores/arduino/Arduino.h

@@ -39,6 +39,7 @@ extern "C"{
 #define clockCyclesToMicroseconds(a) ( ((a) * 1000L) / (SystemCoreClock / 1000L) )
 #define microsecondsToClockCycles(a) ( (a) * (SystemCoreClock / 1000000L) )
 
+void yield(void);
 
 #include "wiring.h"
 #include "wiring_digital.h"

hardware/arduino/sam/cores/arduino/hooks.c

@@ -0,0 +1,31 @@
+/*
+  Copyright (c) 2012 Arduino.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+/**
+ * Empty yield() hook.
+ *
+ * This function is intended to be used by library writers to build
+ * libraries or sketches that supports cooperative threads.
+ *
+ * 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")));

hardware/arduino/sam/cores/arduino/wiring.c

@@ -43,19 +43,18 @@ uint32_t micros( void )
     return count * 1000 + (SysTick->LOAD + 1 - ticks) / (SystemCoreClock/1000000) ;
 }
 
-void delay( uint32_t dwMs )
+void delay( uint32_t ms )
 {
-	Wait( dwMs ) ;
+    uint32_t end = GetTickCount() + ms;
+    while (GetTickCount() < end)
+    	yield();
 }
 
-void delayMicroseconds( uint32_t dwUs )
+void delayMicroseconds( uint32_t us )
 {
-	uint32_t dwStartMicros=micros() ;
-
-	while ( (micros() - dwStartMicros) < dwUs )
-	{
-		//	do nothing
-	}
+	uint32_t start = micros();
+	while ((micros() - start) < us)
+		yield();
 }
 
 /*

hardware/arduino/sam/libraries/Scheduler/Scheduler.cpp

@@ -122,12 +122,6 @@ void yield(void) {
 	coopDoYield(cur);
 }
 
-void wait(uint32_t ms) {
-	uint32_t start = millis();
-	while (millis() - start < ms)
-		yield();
-}
-
 }; // extern "C"
 
 SchedulerClass::SchedulerClass() {

hardware/arduino/sam/libraries/Scheduler/Scheduler.h

@@ -22,9 +22,6 @@
 extern "C" {
 	typedef void (*SchedulerTask)(void);
 	typedef void (*SchedulerParametricTask)(void *);
-
-	void wait(uint32_t ms);
-	void yield();
 }
 
 class SchedulerClass {
@@ -34,7 +31,6 @@ public:
 	static void start(SchedulerTask task, uint32_t stackSize = 1024);
 	static void start(SchedulerParametricTask task, void *data, uint32_t stackSize = 1024);
 
-	static void wait(uint32_t ms) { ::wait(ms); };
 	static void yield() { ::yield(); };
 };
 

hardware/arduino/sam/libraries/Scheduler/examples/MultipleBlinks/MultipleBlinks.ino

@@ -14,10 +14,8 @@
  This example code is in the public domain
  
  http://arduino.cc/en/Tutorial/MultipleBlinks
-
 */
 
-
 // Include Scheduler since we want to manage multiple tasks.
 #include <Scheduler.h>
 
@@ -44,21 +42,20 @@ void loop() {
   digitalWrite(led1, HIGH);
 
   // IMPORTANT:
-  // We must use 'wait' instead of 'delay' to guarantee
-  // that the other tasks get executed.
-  // ('wait' passes control to other tasks while waiting)
-  wait(1000);
+  // When multiple tasks are running 'delay' passes control to
+  // other tasks while waiting and guarantees they get executed.
+  delay(1000);
 
   digitalWrite(led1, LOW);
-  wait(1000);
+  delay(1000);
 }
 
 // Task no.2: blink LED with 0.1 second delay.
 void loop2() {
   digitalWrite(led2, HIGH);
-  wait(100);
+  delay(100);
   digitalWrite(led2, LOW);
-  wait(100);
+  delay(100);
 }
 
 // Task no.3: accept commands from Serial port

hardware/arduino/sam/libraries/Scheduler/keywords.txt

@@ -12,8 +12,6 @@ Scheduler	KEYWORD1
 # Methods and Functions (KEYWORD2)
 #######################################
 
-yield	KEYWORD2
-wait	KEYWORD2
 startLoop	KEYWORD2
 
 #######################################