Subversion Repositories openrisc_2011-10-31

/*  timer_isr()

 *

 *  This ISR is used to bump a count of interval "overflow" interrupts which

 *  have occurred since the timer was started. The number of overflows is taken

 *  into account in the Read_timer() routine.

 *

 *  Input parameters:  NONE

 *

 *  Output parameters:  NONE

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  Modifications of respective RTEMS file: COPYRIGHT (c) 1994.

 *  Copyright (c) 1998, National Research Council of Canada

 *

 *  $Id: timerisr.S,v 1.2 2001-09-27 12:00:20 chris Exp $

 */

#include "asm.h"

BEGIN_CODE

.set INTR_CLEAR_REG,    0xfff40074      | interrupt clear register

.set T1_CNTRL_REG,      0xfff40060      | tick timer 1 control register

.set CLEAR_INT,         0x01000000      | clear tick 1 interrupt

.set CLEAR_OVF,         0x00000004      | clear tick 1 overflow counter

        PUBLIC (Ttimer_val)

        PUBLIC (timerisr)

SYM (timerisr):

        move.l  a0, -(a7)               | save a0

        move.l  d0, -(a7)               | save d0

        move.w  sr, -(a7)               | save ccr

        movea.l #INTR_CLEAR_REG, a0     | a0 = addr of intr clr reg

        ori.l   #CLEAR_INT, (a0)        | clear tick timer 1 intr

        movea.l #T1_CNTRL_REG, a0       | a0 = addr of t1 cntrl reg

        move.l  (a0), d0                | read overflow counter

        lsr.l   #4, d0                  | put overflow in low order bits

        andi.l  #0xF, d0                | keep only overflow

        add.l   d0, SYM (Ttimer_val)    | increment timer value

        ori.l   #CLEAR_OVF, (a0)        | clear overflow counter

        move.w  (a7)+, sr               | restore ccr

        move.l  (a7)+, d0               | restore d0

        move.l  (a7)+, a0               | restore a0

        rte

END_CODE

END