[sam] Fixed wrap-around bug in delay() (Mark Tillotson)

cmaglie · cmaglie · commit 9be7c15167d7 · 2013-12-14T00:33:57.000+01:00
Fixes arduino#1736
diff --git a/cores/arduino/wiring.c b/cores/arduino/wiring.c
@@ -25,7 +25,7 @@ extern "C" {
 uint32_t millis( void )
 {
 // todo: ensure no interrupts
-	return GetTickCount() ;
+    return GetTickCount() ;
 }
 
 // Interrupt-compatible version of micros
@@ -74,9 +74,12 @@ uint32_t micros( void )
 
 void delay( uint32_t ms )
 {
-    uint32_t end = GetTickCount() + ms;
-    while (GetTickCount() < end)
-    	yield();
+    if (ms == 0)
+        return;
+    uint32_t start = GetTickCount();
+    do {
+        yield();
+    } while (GetTickCount() - start < ms);
 }
 
 #if defined ( __ICCARM__ ) /* IAR Ewarm 5.41+ */

Original file line number	Diff line number	Diff line change
`@@ -25,7 +25,7 @@ extern "C" {`
`25`	`25`	`uint32_t millis( void )`
`26`	`26`	`{`
`27`	`27`	`// todo: ensure no interrupts`
`28`		`- return GetTickCount() ;`
	`28`	`+ return GetTickCount() ;`
`29`	`29`	`}`
`30`	`30`
`31`	`31`	`// Interrupt-compatible version of micros`
`@@ -74,9 +74,12 @@ uint32_t micros( void )`
`74`	`74`
`75`	`75`	`void delay( uint32_t ms )`
`76`	`76`	`{`
`77`		`- uint32_t end = GetTickCount() + ms;`
`78`		`- while (GetTickCount() < end)`
`79`		`- yield();`
	`77`	`+ if (ms == 0)`
	`78`	`+ return;`
	`79`	`+ uint32_t start = GetTickCount();`
	`80`	`+ do {`
	`81`	`+ yield();`
	`82`	`+ } while (GetTickCount() - start < ms);`
`80`	`83`	`}`
`81`	`84`
`82`	`85`	`#if defined ( __ICCARM__ ) /* IAR Ewarm 5.41+ */`