//-------------------------------------------------------------------------
//-------------------------------------------------------------------------

extern void PUT32 ( unsigned int, unsigned int );
extern unsigned int GET32 ( unsigned int );
extern void dummy ( unsigned int );

#define ARM_TIMER_LOD 0x2000B400
#define ARM_TIMER_VAL 0x2000B404
#define ARM_TIMER_CTL 0x2000B408
#define ARM_TIMER_DIV 0x2000B41C
#define ARM_TIMER_CNT 0x2000B420

#define SYSTIMERCLO 0x20003004
#define GPFSEL1 0x20200004
#define GPSET0  0x2020001C
#define GPCLR0  0x20200028

//From experiments and from the manual the freerunning ARM timer is
//not affected by the timer enable bit.  Not affected by the 0x41C
//prescaler.  Not affected by bits 3:2 of the control register.
//And is affected by bits 23:16 of the control register.

//It still appears as if the system timer is 250Mhz as mentioned somewhere
//in the manual (starts up at 250MHz).
//If we divide 250MHz/250 we can make the free running clock 1mhz
//wait for 4 million ticks and the led will change state every 4 seconds
//Note the free running timer is an up counting timer, the other arm
//timer is a down counter.

#define TIMEOUT 4000000


//-------------------------------------------------------------------------
int notmain ( void )
{
    unsigned int ra;
    unsigned int rb;

    ra=GET32(GPFSEL1);
    ra&=~(7<<18);
    ra|=1<<18;
    PUT32(GPFSEL1,ra);

    PUT32(ARM_TIMER_CTL,0x00F90000);
    PUT32(ARM_TIMER_CTL,0x00F90200);

    rb=GET32(ARM_TIMER_CNT);
    while(1)
    {
        PUT32(GPSET0,1<<16);
        while(1)
        {
            ra=GET32(ARM_TIMER_CNT);
            if((ra-rb)>=TIMEOUT) break;
        }
        rb+=TIMEOUT;
        PUT32(GPCLR0,1<<16);
        while(1)
        {
            ra=GET32(ARM_TIMER_CNT);
            if((ra-rb)>=TIMEOUT) break;
        }
        rb+=TIMEOUT;
    }
    return(0);
}
//-------------------------------------------------------------------------
//-------------------------------------------------------------------------