File content as of revision 31:f6ff7fdb9c67:

#include <stdint.h>
#include <stdbool.h>

#include "timer.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;
}

static uint32_t secondsBaseCount = 0;

uint32_t TimerCountSinceLastSecond()
{
    return TC - secondsBaseCount; 
}
int32_t TimerMultiplyFractionalPart(int32_t value, uint32_t timerCountSinceLastSecond)
{
    int64_t fraction;
    
    fraction = timerCountSinceLastSecond;
    fraction <<= 32;
    fraction /= TIMER_COUNT_PER_SECOND;
              
    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.
    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
}