94 lines
4.3 KiB
ArmAsm
94 lines
4.3 KiB
ArmAsm
##############################################################################
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# crt0.S -- CRX default start-up routine #
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# #
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# Copyright (c) 2004 National Semiconductor Corporation #
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# #
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# The authors hereby grant permission to use, copy, modify, distribute, #
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# and license this software and its documentation for any purpose, provided #
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# that existing copyright notices are retained in all copies and that this #
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# notice is included verbatim in any distributions. No written agreement, #
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# license, or royalty fee is required for any of the authorized uses. #
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# Modifications to this software may be copyrighted by their authors #
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# and need not follow the licensing terms described here, provided that #
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# the new terms are clearly indicated on the first page of each file where #
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# they apply. #
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# #
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# This is the start routine of your CRX program. #
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# It is linked with your application automatically. You can use #
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# this routine as a template and modify it to your needs, yet this #
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# file must be supplied for the compiler. #
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# It is assumed that the following symbols are defined in your linker #
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# script: __STACK_START, __ISTACK_START, __DATA_START, __DATA_END, #
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# __DATA_IMAGE_START, __BSS_START, __BSS_END. #
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##############################################################################
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.text
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.align 4
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.globl _main
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.globl _start
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.globl _atexit
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.globl _exit
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.globl __dispatch_table
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_start:
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#----------------------------------------------------------------------------#
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# Initialize the stack pointers. The constants __STACK_START and #
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# __ISTACK_START should be defined in the linker script. #
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movd $__STACK_START, sp
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movd $__ISTACK_START, r0
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mtpr r0, isp
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#----------------------------------------------------------------------------#
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# Initialize the default sections according to the linker script. #
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movd $__DATA_END, r4
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subd $__DATA_START, r4
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movd $__DATA_START, r2
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movd $__DATA_IMAGE_START, r3
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bal ra, _memcpy
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movd $__BSS_END, r4
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subd $__BSS_START, r4
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movd $__BSS_START, r2
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movd $0, r3
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bal ra, _memset
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#----------------------------------------------------------------------------#
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# Initialize the intbase (pointer to the dispatch table). #
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movd $__dispatch_table, r0
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mtpr r0, intbase
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#----------------------------------------------------------------------------#
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# Handle global and static constructurs execution and setup #
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# destructors to be called from exit. #
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bal ra, _init
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movd $_fini, r2
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bal ra, _atexit
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#----------------------------------------------------------------------------#
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# Here you may add initializations that are specific to your #
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# environment. For example: #
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# 1. Configure wait states and other BIU parameters in order to get #
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# the best performance out of your target (see the specification #
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# document). #
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# 2. Enable maskable interrupts that should be enabled when your #
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# program starts to execute. #
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#----------------------------------------------------------------------------#
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# Jump to the main function in your application. #
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bal ra, _main
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#----------------------------------------------------------------------------#
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# Upon returning from the main function (if it isn't an infinite loop), #
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# jump to the exit function. The exit function is located in the #
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# library 'libc.a'. #
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movd r0, r2 # _main return value is passed as a
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# parameter to exit.
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br _exit # returns control to the debugger.
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