/* TICK1190.C
 *
 * Example code for SBC1190 to set up 10ms timer routine */

/*
	The RUN.EXE firmware sets up timer 2 as a pre-scaler.  Timer 2
	divides the CPU clock down to 187.5kHz (for a 12MHz SBC1190),
	312.5kHz (for a 20MHz SBC1190), or 390.625kHz (for a 25MHz
	SBC1190).  This signal is then fed into timers 0 and 1.
	Timer 0 is used by RUN.EXE to further divide the signal down
	to a standard DOS 18.2Hz timer tick.  Timer 1 is not used.

	This example for a 12MHz SBC1190 uses timer 1 to set up an
	interrupt service routine that is called every 10ms.

	NOTE:  The timer 1 interrupt vector is determined by the
	80C188EB processor and is fixed as being Int 12h.
	This interrupt is used by the RUN.EXE firmware to provide
	the PC-compatible memory-available routine.  Any routines
	that require Int 12h to be PC-compatible (e.g. memory
	allocation), should be run before revectoring this interrupt
*/

void far interrupt timer_10ms_int(void);

#ifndef __TURBOC__

 #ifndef outport
     #define outport    outpw
 #endif
 #ifndef inport
     #define inport     inpw
 #endif

 #ifndef setvect
     #define setvect            _dos_setvect
 #endif
#endif

#define EOI     0xFF02
#define T1CMPA  0xFF3A
#define T1CON   0xFF3E
#define I0CON   0xFF18
#define IMASK   0xFF08

unsigned int numticks;

void setup_10ms_timer_interrupt(void)
{
	/* setup timer 1 counter */
	/* timer 0 is prescaler, output = 187.5kHz */
	/* 187.5kHz/1875 = 100 Hz or approx 10 ms */
	outport(T1CMPA, 1875);

	/* setup timer 1 interrupt vector */
	/* Note that Int 12h may no longer be used to determine the
	   memory available after this interrupt is revectored */
	setvect(0x12, timer_10ms_int);

	/* setup timer 1 mode - continuous with int */
	outport (T1CON, 0xE009);

	/* enable timer 1 int */
	outport(IMASK, (inport(IMASK) & 0xFFFE));
}

void far interrupt timer_10ms_int(void)
{
	/* handle interrupt here */
	numticks++;

	outport (EOI, 0x8000);         /* EOI */
}

void main(void)
{
	setup_10ms_timer_interrupt();
}