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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libbsp/] [m68k/] [mvme167/] [timer/] [timerisr.S] - Rev 30
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/* 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
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