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/* Startup code for ARM & ELF
Copyright (C) 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* This is the canonical entry point, usually the first thing in the text
segment.
Note that the code in the .init section has already been run.
This includes _init and _libc_init
At this entry point, most registers' values are unspecified, except for:
r0 Contains a function pointer to be registered with `atexit'.
This is how the dynamic linker arranges to have DT_FINI
functions called for shared libraries that have been loaded
before this code runs.
sp The stack contains the arguments and environment:
0(%esp) argc
4(%esp) argv[0]
...
(4*argc)(%esp) NULL
(4*(argc+1))(%esp) envp[0]
...
NULL
*/
.text
.globl _start
_start:
/* Clear the frame pointer. The Intel ABI suggests this be done,
to mark the outermost frame obviously. This seems like a
sensible thing to do */
mov fp, #0
/* r0 contains the address of the shared library termination
function, which we will register with `atexit' to be called by
`exit'. I suspect that on some systems, and when statically
linked, this will not be set by anything to any function
pointer; hopefully it will be zero so we don't try to call
random pointers. */
cmp r0,#0
blne atexit(PLT)
/* Do essential libc initialization. In statically linked
programs under the GNU Hurd, this is what sets up the
arguments on the stack for the code below. For dyn-link
programs, this has been run already, in the .init code. */
#ifndef PIC
bl __libc_init_first
/* Extract the arguments and environment as encoded on the stack
and set up the arguments for `main': argc, argv, envp. */
ldr r0,[sp]
add r1,sp,#4
add r2,r1,r0,lsl #2
add r2,r2,#4
/* save a copy of envp while we have it */
ldr r3,L_environ
str r2,[r3]
/* Call `_init', which is the entry point to our own `.init'
section; and register with `atexit' to have `exit' call
`_fini', which is the entry point to our own `.fini' section. */
bl _init
ldr r0,L_fini
bl atexit
b L_pfini
L_fini: .word _fini
L_environ: .word _environ
L_pfini:
#endif
/* rebuild the arg list for main() */
ldr r0,[sp]
add r1,sp,#4
add r2,r1,r0,lsl #2
add r2,r2,#4
/* Call the user's main function, and exit with its value. */
bl main
bl exit
/* should never get here....*/
bl abort
/* Define a symbol for the first piece of initialized data. */
.data
.globl __data_start
__data_start:
.long 0
.weak data_start
data_start = __data_start
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