source: rtems/c/src/lib/libcpu/arm/lpc22xx/irq/bsp_irq_asm.S @ 8b7e446e

/*
 *  LPC22XX Intererrupt handler
 *
 *  Copyright (c) 2002 by Jay Monkman <jtm@lopingdog.com>
 *
 *  Modified by ray
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *
 *  http://www.rtems.com/license/LICENSE.
 *
 *
 *  bsp_irq_asm.S,v 1.1 2002/11/13 17:55:06 joel Exp
 */
#define __asm__
        
/* 
 * BSP specific interrupt handler for INT or FIQ. In here
 * you do determine which interrupt happened and call its
 * handler.
 */
        .globl ExecuteITHandler
ExecuteITHandler :

/*
 * Look at interrupt status register to determine source.
 * From source, determine offset into expanded vector table
 * and load handler address into r0.
 */
 
  ldr   r0, =0xFFFFF030  /* Read the vector number */
  ldr   r1, [r0]

  /* find the ISR's address based on the vector VICVectAddr0 */ 
  /*ldr   r0, =0xFFFFF100*/
  /*ldr r0, [r0, r1, LSL #2]*/  /* Read the address */


  stmdb   sp!,{lr}
  ldr     lr, =IRQ_return         /* prepare the return from handler  */

  mov     pc, r1                /* EXECUTE INT HANDLER */

IRQ_return:
  ldmia sp!,{lr}

  mov pc, lr