Diff: timer/timer.c

Revision:

35:ba9f575aa3c6

Parent:

34:aeb58975e61a

Child:

38:25b2a3c494aa

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/timer/timer.c	Sat Dec 01 15:43:59 2018 +0000
@@ -0,0 +1,62 @@
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "timer.h"
+#include "tick.h"
+
+#define TCR  (*((volatile unsigned *) 0x40004004))
+#define TC   (*((volatile unsigned *) 0x40004008))
+#define PR   (*((volatile unsigned *) 0x4000400C))
+#define MCR  (*((volatile unsigned *) 0x40004014))
+#define CTCR (*((volatile unsigned *) 0x40004070))
+
+uint32_t TimerNowCount()
+{
+    return TC;
+}
+uint32_t TimerIntervalCount(uint32_t* pLastCount)
+{
+    uint32_t thisCount = TC;
+    uint32_t period = thisCount - *pLastCount;    
+    *pLastCount = thisCount;
+    return period;
+}
+uint32_t TimerSinceCount(uint32_t startCount)
+{
+    return TC - startCount; 
+}
+uint32_t TimerSinceMs(uint32_t startCount)
+{
+    uint32_t count = TC - startCount;
+    return count / TIMER_COUNT_PER_MS;
+}
+
+bool TimerIntervalHasElapsed(uint32_t* pBaseCount, uint32_t intervalCount)
+{
+    if (TC - *pBaseCount > intervalCount) //All unsigned wrap around arithmetic
+    {
+        *pBaseCount += intervalCount;
+        return true;
+    }
+    return false;
+}
+
+int32_t TimerMultiplyFractionalPart(int32_t value, uint32_t timerCountSinceStart, uint32_t interval)
+{
+    int64_t fraction;
+    
+    fraction = timerCountSinceStart;
+    fraction <<= 32;
+    fraction /= interval;
+              
+    return (value * fraction) >> 32;
+}
+
+void TimerInit()
+{    
+    TCR     =     2; // 21.6.2 Timer Control Register - Reset TC and PC.
+    CTCR    =     0; // 21.6.3 Count Control Register - Timer mode
+    PR      =     0; // 21.6.5 Prescale register      - Don't prescale 96MHz clock (divide by PR+1).
+    MCR     =     0; // 21.6.8 Match Control Register - no interrupt or reset
+    TCR     =     1; // 21.6.2 Timer Control Register - Enable TC and PC
+}