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 ##############################################################################

 # crt0.S -- CRX default start-up routine                                     #

 #                                                                            #

 # Copyright (c) 2004 National Semiconductor Corporation                      #

 #                                                                            #

 # The authors hereby grant permission to use, copy, modify, distribute,      #

 # and license this software and its documentation for any purpose, provided  #

 # that existing copyright notices are retained in all copies and that this   #

 # notice is included verbatim in any distributions. No written agreement,    #

 # license, or royalty fee is required for any of the authorized uses.        #

 # Modifications to this software may be copyrighted by their authors         #

 # and need not follow the licensing terms described here, provided that      #

 # the new terms are clearly indicated on the first page of each file where   #

 # they apply.                                                                #

 #                                                                            #

 # This is the  start routine of your CRX program.                            #

 # It is linked with your application automatically. You can use              #

 # this routine as a template and modify it to your needs, yet this           #

 # file must be supplied for the compiler.                                    #

 # It is assumed that the following symbols are defined in your linker        #

 # script: __STACK_START, __ISTACK_START, __DATA_START, __DATA_END,           #

 # __DATA_IMAGE_START, __BSS_START, __BSS_END.                                #

 ##############################################################################

        .text

        .align  4

        .globl          _main

        .globl          _start

        .globl          _atexit

        .globl          _exit

        .globl          __dispatch_table

_start:

 #----------------------------------------------------------------------------#

 # Initialize the stack pointers. The constants __STACK_START and             #

 # __ISTACK_START should be defined in the linker script.                     #

        movd    $__STACK_START, sp

        movd    $__ISTACK_START, r0

        mtpr    r0, isp

 #----------------------------------------------------------------------------#

 # Initialize the default sections according to the linker script.            #

        movd    $__DATA_END, r4

        subd    $__DATA_START, r4

        movd    $__DATA_START, r2

        movd    $__DATA_IMAGE_START, r3

        bal     ra,     _memcpy

        movd    $__BSS_END, r4

        subd    $__BSS_START, r4

        movd    $__BSS_START, r2

        movd    $0, r3

        bal     ra,     _memset

 #----------------------------------------------------------------------------#

 # Initialize the intbase (pointer to the dispatch table).                    #

        movd    $__dispatch_table, r0

        mtpr    r0, intbase

 #----------------------------------------------------------------------------#

 # Handle global and static constructurs execution and setup                  #

 # destructors to be called from exit.                                        #

        bal     ra,     _init

        movd    $_fini, r2

        bal     ra, _atexit

 #----------------------------------------------------------------------------#

 # Here you may add initializations that are specific to your                 #

 # environment. For example:                                                  #

 # 1. Configure wait states and other BIU parameters in order to get          #

 #    the best performance out of your target (see the specification          #

 #    document).                                                              #

 # 2. Enable maskable interrupts that should be enabled when your             #

 #    program starts to execute.                                              #

 #----------------------------------------------------------------------------#

 # Jump to the main function in your application.                             #

        bal     ra, _main

 #----------------------------------------------------------------------------#

 # Upon returning from the main function (if it isn't an infinite loop),      #

 # jump to the exit function. The exit function is located in the             #

 # library 'libc.a'.                                                          #

        movd    r0, r2          # _main return value is passed as a

                                                # parameter to exit.

        br      _exit                   # returns control to the debugger.