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/*
 * (c) 1999, Eric Valette valette@crf.canon.fr
 *
 *
 *  This file contains the assembly code for the PowerPC 
 *  exception veneers for RTEMS.
 *
 * $Id: vectors.S,v 1.2 2001-09-27 12:01:09 chris Exp $
 */
        


#include <bsp/vectors.h>
#include <libcpu/cpu.h>
#include <rtems/score/targopts.h>
#include "asm.h"
        

#define SYNC \
        sync; \
        isync
        
        PUBLIC_VAR (__rtems_start)
        .section .entry_point_section,"awx",@progbits
/*
 * Entry point information used by bootloader code
 */
SYM (__rtems_start):            
        .long   __rtems_entry_point

        /*
         * end of special Entry point section
         */     
        .text
        .p2align 5      
                
PUBLIC_VAR(default_exception_vector_code_prolog)
SYM (default_exception_vector_code_prolog):
        /*
         * let room for exception frame
         */
        stwu    r1, - (EXCEPTION_FRAME_END)(r1)
        stw     r3, GPR3_OFFSET(r1)
        stw     r2, GPR2_OFFSET(r1)
        mflr    r2
        stw     r2, EXC_LR_OFFSET(r1)
        bl      0f
0:      /*
         * r3 = exception vector entry point 
         * (256 * vector number) + few instructions
         */
        mflr    r3
        /*
         * r3 = r3 >> 8 = vector
         */
        srwi    r3,r3,8
        ba      push_normalized_frame
        
        PUBLIC_VAR (default_exception_vector_code_prolog_size)
        
        default_exception_vector_code_prolog_size= . - default_exception_vector_code_prolog
        
        .p2align 5
PUBLIC_VAR (push_normalized_frame)      
SYM (push_normalized_frame):
        stw     r3, EXCEPTION_NUMBER_OFFSET(r1)
        stw     r0, GPR0_OFFSET(r1)
        mfsrr0  r2
        stw     r2, SRR0_FRAME_OFFSET(r1)
        mfsrr1  r3
        stw     r3, SRR1_FRAME_OFFSET(r1)
        /*
         * Save general purpose registers
         * Already saved in prolog : R1, R2, R3, LR.
         * Saved a few line above  : R0
         *
         * Manual says that "stmw" instruction may be slower than
         * series of individual "stw" but who cares about performance 
         * for the DEFAULT exception handler?
         */
        stmw    r4, GPR4_OFFSET(r1)     /* save R4->R31 */

        mfcr    r31
        stw     r31,  EXC_CR_OFFSET(r1)
        mfctr   r30
        stw     r30,  EXC_CTR_OFFSET(r1)
        mfxer   r28
        stw     r28,  EXC_XER_OFFSET(r1)
        /*
         * compute SP at exception entry
         */
        addi    r2, r1, EXCEPTION_FRAME_END
        /*
         * store it at the right place
         */
        stw     r2, GPR1_OFFSET(r1)
        /*
         * Enable data and instruction address translation, exception nesting
         */
        mfmsr   r3
        ori     r3,r3, MSR_RI | MSR_IR | MSR_DR
        mtmsr   r3
        SYNC
        
        /*
         * Call C exception handler
         */
        /*
         * store the execption frame address in r3 (first param)
         */
        addi    r3, r1, 0x8
        /*
         * globalExceptHdl(r3)
         */
        addis   r4, 0, globalExceptHdl@ha
        lwz     r5, globalExceptHdl@l(r4)
        mtlr    r5
        blrl
        /*
         * Restore registers status
         */
        lwz     r31,  EXC_CR_OFFSET(r1)
        mtcr    r31
        lwz     r30,  EXC_CTR_OFFSET(r1)
        mtctr   r30
        lwz     r29,  EXC_LR_OFFSET(r1)
        mtlr    r29
        lwz     r28,  EXC_XER_OFFSET(r1)
        mtxer   r28

        lmw     r4, GPR4_OFFSET(r1)
        lwz     r2, GPR2_OFFSET(r1)
        lwz     r0, GPR0_OFFSET(r1)

        /*
         * Disable data and instruction translation. Make path non recoverable...
         */
        mfmsr   r3
        xori    r3, r3, MSR_RI | MSR_IR | MSR_DR
        mtmsr   r3
        SYNC
        /*
         * Restore rfi related settings
         */
                 
        lwz     r3, SRR1_FRAME_OFFSET(r1)
        mtsrr1  r3
        lwz     r3, SRR0_FRAME_OFFSET(r1)
        mtsrr0  r3
        
        lwz     r3, GPR3_OFFSET(r1)
        addi    r1,r1, EXCEPTION_FRAME_END
        SYNC
        rfi