/*
	This C language subroutine provides support for the 
	on-chip timer of the ADSP-21020.

	The Run Time Library for the C Language.

	Gordon A. Sterling	(617) 461 - 3076
	DSP Development Tools Engineering

	Created on 1/4/91
	Updated on 5/94 by AS

	#include <21020.h>						<Header>
	int timer_set(unsigned int tperiod, unsigned int tcount);   	<Prototype>
	unsigned int timer_on(void);				    	<Prototype>
	unsigned int timer_off(void);				    	<Prototype>
*/

#include "lib_glob.h"
#include "020_glob.h"

.SEGMENT/CODE	Code_Space_Name;
.FILE 		RTL_FILENAME;

.GLOBAL	    	_timer_set, _timer_on, _timer_off;

_timer_on:	FETCH_RETURN
		JUMP (PC, restore_state) (DB);
		BIT SET MODE2 32;	    /*Enable timer*/
		R0=TCOUNT;

_timer_off:	FETCH_RETURN
		JUMP (PC, restore_state) (DB);
		BIT CLR MODE2 32;	    /*Disable timer*/
		R0=TCOUNT;

_timer_set:	FETCH_RETURN
		TPERIOD=R4;
		TCOUNT=R8;

		R0=MODE2; 
		R0=FEXT R0 BY 5:1;		/*Deposit bit 5 into LSB of R0*/
	
restore_state:	RETURN (DB);
		RESTORE_STACK
		RESTORE_FRAME

.ENDSEG;