source: rtems/c/src/exec/score/cpu/powerpc/irq_stub.s @ 591d45e

/*  irq_stub.s  1.0 - 95/08/08
 *
 *  This file contains the interrupt handler assembly code for the PowerPC
 *  implementation of RTEMS.  It is #included from cpu_asm.s.
 *
 *  Author:     Andrew Bray <andy@i-cubed.demon.co.uk>
 *
 *  COPYRIGHT (c) 1995 by i-cubed ltd.
 *
 *  To anyone who acknowledges that this file is provided "AS IS"
 *  without any express or implied warranty:
 *      permission to use, copy, modify, and distribute this file
 *      for any purpose is hereby granted without fee, provided that
 *      the above copyright notice and this notice appears in all
 *      copies, and that the name of i-cubed limited not be used in
 *      advertising or publicity pertaining to distribution of the
 *      software without specific, written prior permission.
 *      i-cubed limited makes no representations about the suitability
 *      of this software for any purpose.
 *
 *  $Id$
 */

/*  void __ISR_Handler()
 *
 *  This routine provides the RTEMS interrupt management.
 *  The vector number is in r0. R0 has already been stacked.
 *
 */
        /* Finish off the interrupt frame */
        stw     r2, IP_2(r1)
        stw     r3, IP_3(r1)
        stw     r4, IP_4(r1)
        stw     r5, IP_5(r1)
        stw     r6, IP_6(r1)
        stw     r7, IP_7(r1)
        stw     r8, IP_8(r1)
        stw     r9, IP_9(r1)
        stw     r10, IP_10(r1)
        stw     r11, IP_11(r1)
        stw     r12, IP_12(r1)
        stw     r13, IP_13(r1)
        stmw    r28, IP_28(r1)
        mfcr    r5
        mfctr   r6
        mfxer   r7
        mflr    r8
        mfsrr0  r9
        mfsrr1  r10
        /* Establish addressing */
        mfsprg3 r11
        dcbt    r0, r11
        stw     r5, IP_CR(r1)
        stw     r6, IP_CTR(r1)
        stw     r7, IP_XER(r1)
        stw     r8, IP_LR(r1)
        stw     r9, IP_PC(r1)
        stw     r10, IP_MSR(r1)

        lwz     r30, Vector_table(r11)
        slwi    r4,r0,2
        lwz     r28, Nest_level(r11)
        add     r4, r4, r30
        
        lwz     r30, 0(r28)
        mr      r3, r0
        lwz     r31, Stack(r11)
  /*
   *  #if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE )
   *    if ( _ISR_Nest_level == 0 )
   *      switch to software interrupt stack
   *  #endif
   */
        /* Switch stacks, here we must prevent ALL interrupts */
        cmpwi   r30, 0
        lwz     r29, Disable_level(r11)
        subf    r31,r1,r31
        bne     LABEL (nested)
        stwux   r1,r1,r31
LABEL (nested):
  /*
   *  _ISR_Nest_level++;
   */
        lwz     r31, 0(r29)
        addi    r30,r30,1
        stw     r30,0(r28)
        /* From here on out, interrupts can be re-enabled. RTEMS
         * convention says not.
         */
        lwz     r4,0(r4)
  /*
   *  _Thread_Dispatch_disable_level++;
   */
        addi    r31,r31,1
        stw     r31, 0(r29)
  /*
   *  (*_ISR_Vector_table[ vector ])( vector );
   */
#if (PPC_ABI == PPC_ABI_POWEROPEN)
        lwz     r6,0(r4)
        lwz     r2,4(r4)
        mtlr    r6
        lwz     r11,8(r4)
#endif
#if (PPC_ABI == PPC_ABI_GCC27)
        lwz     r2, Default_r2(r11)
        mtlr    r4
        lwz     r2, 0(r2)
#endif
#if (PPC_ABI == PPC_ABI_SVR4 || PPC_ABI == PPC_ABI_EABI)
        mtlr    r4
        lwz     r2, Default_r2(r11)
        lwz     r13, Default_r13(r11)
        lwz     r2, 0(r2)
        lwz     r13, 0(r13)
#endif
        mr      r4,r1
        blrl
        /* NOP marker for debuggers */
        or      r6,r6,r6

        /*      We must re-disable the interrupts */
        mfsprg3 r11
        mfsprg2 r0
        mtmsr   r0

  /*
   *  if (--Thread_Dispatch_disable,--_ISR_Nest_level)
   *    goto easy_exit;
   */
        addi    r30, r30, -1
        cmpwi   r30, 0
        addi    r31, r31, -1
        stw     r30, 0(r28)
        stw     r31, 0(r29)
        bne     LABEL (easy_exit)

        lwz     r30, Switch_necessary(r11)

  /*
   *  #if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE )
   *    restore stack
   *  #endif
   */
        lwz     r1,0(r1)
        lwz     r30, 0(r30)
        lwz     r31, Signal(r11)
        
  /*  
   *  if ( _Context_Switch_necessary )
   *    goto switch
   */
        cmpwi   r30, 0
        lwz     r28, 0(r31)
        bne     LABEL (switch)
  /*  
   *  if ( !_ISR_Signals_to_thread_executing )
   *    goto easy_exit
   *  _ISR_Signals_to_thread_executing = 0;
   */
        cmpwi   r28, 0
        li      r6,0
        beq     LABEL (easy_exit)
        stw     r6, 0(r31)

  /*
   * switch:
   *  call _Thread_Dispatch() or prepare to return to _ISR_Dispatch
   */
LABEL (switch):
#if (PPC_ABI == PPC_ABI_POWEROPEN)
        lwz     r2, Dispatch_r2(r11)
#else
        /* R2 and R13 still hold their values from the last call */
#endif
        bl      PROC (_Thread_Dispatch)
        /* NOP marker for debuggers */
        or      r6,r6,r6
  /*
   *  prepare to get out of interrupt
   */
        /* Re-disable IRQs */
        mfsprg2 r0
        mtmsr   r0
  /*
   *  easy_exit:
   *  prepare to get out of interrupt
   *  return from interrupt
   */
LABEL (easy_exit):
        lwz     r5, IP_CR(r1)
        lwz     r6, IP_CTR(r1)
        lwz     r7, IP_XER(r1)
        lwz     r8, IP_LR(r1)
        lwz     r9, IP_PC(r1)
        lwz     r10, IP_MSR(r1)
        mtcrf   255,r5
        mtctr   r6
        mtxer   r7
        mtlr    r8
        mtsrr0  r9
        mtsrr1  r10
        lwz     r0, IP_0(r1)
        lwz     r2, IP_2(r1)
        lwz     r3, IP_3(r1)
        lwz     r4, IP_4(r1)
        lwz     r5, IP_5(r1)
        lwz     r6, IP_6(r1)
        lwz     r7, IP_7(r1)
        lwz     r8, IP_8(r1)
        lwz     r9, IP_9(r1)
        lwz     r10, IP_10(r1)
        lwz     r11, IP_11(r1)
        lwz     r12, IP_12(r1)
        lwz     r13, IP_13(r1)
        lmw     r28, IP_28(r1)
        lwz     r1, 0(r1)