Diff: timer.c

Revision:

33:b9e3c06e7dab

Parent:

31:f6ff7fdb9c67

Child:

34:aeb58975e61a

--- a/timer.c	Thu Nov 29 18:43:27 2018 +0000
+++ b/timer.c	Fri Nov 30 18:28:04 2018 +0000
@@ -2,6 +2,7 @@
 #include <stdbool.h>
 
 #include "timer.h"
+#include "tick.h"
 
 #define TCR  (*((volatile unsigned *) 0x40004004))
 #define TC   (*((volatile unsigned *) 0x40004008))
@@ -30,43 +31,27 @@
     return count / TIMER_COUNT_PER_MS;
 }
 
-static uint32_t secondsBaseCount = 0;
-
-uint32_t TimerCountSinceLastSecond()
+bool TimerIntervalHasElapsed(uint32_t* pBaseCount, uint32_t intervalCount)
 {
-    return TC - secondsBaseCount; 
+    if (TC > *pBaseCount + intervalCount) //All unsigned wrap around arithmetic
+    {
+        *pBaseCount += intervalCount;
+        return true;
+    }
+    return false;
 }
-int32_t TimerMultiplyFractionalPart(int32_t value, uint32_t timerCountSinceLastSecond)
+
+int32_t TimerMultiplyFractionalPart(int32_t value, uint32_t timerCountSinceStart, uint32_t interval)
 {
     int64_t fraction;
     
-    fraction = timerCountSinceLastSecond;
+    fraction = timerCountSinceStart;
     fraction <<= 32;
-    fraction /= TIMER_COUNT_PER_SECOND;
+    fraction /= interval;
               
     return (value * fraction) >> 32;
 }
 
-bool TimerHadSecond = false;
-
-//Counts from zero to 2^32 and wraps around after:
-// 13.7 years if  10 per second - scan time must be less than 100mS
-// 1.37 years if 100 per second - scan time must be less than  10mS
-uint32_t TimerTicks = 0;
-
-void TimerMain()
-{
-    TimerHadSecond = TimerCountSinceLastSecond() > TIMER_COUNT_PER_SECOND;
-    if (TimerHadSecond) secondsBaseCount        += TIMER_COUNT_PER_SECOND;
-    
-    static uint32_t tickBaseCount = 0;
-    
-    if (TC - tickBaseCount > TIMER_COUNT_PER_SECOND / TIMER_TICKS_PER_SECOND)
-    {
-        TimerTicks++;
-        tickBaseCount += TIMER_COUNT_PER_SECOND / TIMER_TICKS_PER_SECOND;
-    }
-}
 void TimerInit()
 {    
     TCR     =     2; // 21.6.2 Timer Control Register - Reset TC and PC.