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Diffstat (limited to 'libgloss/crx/crt0.S')
| -rw-r--r-- | libgloss/crx/crt0.S | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/libgloss/crx/crt0.S b/libgloss/crx/crt0.S new file mode 100644 index 000000000..c49849728 --- /dev/null +++ b/libgloss/crx/crt0.S @@ -0,0 +1,93 @@ + ############################################################################## + # 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. + |