| ############################################################################## |
| # 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. |
| |