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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.
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