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

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);
}
//-------------------------------------------------------------------------
//-------------------------------------------------------------------------


//-------------------------------------------------------------------------
//
// Copyright (c) 2012 David Welch dwelch@dwelch.com
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//-------------------------------------------------------------------------