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/* crt1.s for Solaris 2, x86
Copyright (C) 1993-2013 Free Software Foundation, Inc.
Written By Fred Fish, Nov 1992
This file is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
This file 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
General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* This file takes control of the process from the kernel, as specified
in section 3 of the System V Application Binary Interface, Intel386
Processor Supplement. It has been constructed from information obtained
from the ABI, information obtained from single stepping existing
Solaris executables through their startup code with gdb, and from
information obtained by single stepping executables on other i386 SVR4
implementations. This file is the first thing linked into any
executable. */
#ifndef GCRT1
.ident "GNU C crt1.s"
#define CLEANUP _cleanup
#else
/* This is a modified crt1.s by J.W.Hawtin <oolon@ankh.org> 15/8/96,
to allow program profiling, by calling monstartup on entry and _mcleanup
on exit. */
.ident "GNU C gcrt1.s"
#define CLEANUP _mcleanup
#endif
.weak _cleanup
.weak _DYNAMIC
.text
/* Start creating the initial frame by pushing a NULL value for the return
address of the initial frame, and mark the end of the stack frame chain
(the innermost stack frame) with a NULL value, per page 3-32 of the ABI.
Initialize the first stack frame pointer in %ebp (the contents of which
are unspecified at process initialization). */
.globl _start
_start:
pushl $0x0
pushl $0x0
movl %esp,%ebp
/* As specified per page 3-32 of the ABI, %edx contains a function
pointer that should be registered with atexit(), for proper
shared object termination. Just push it onto the stack for now
to preserve it. We want to register _cleanup() first. */
pushl %edx
/* Check to see if there is an _cleanup() function linked in, and if
so, register it with atexit() as the last thing to be run by
atexit(). */
movl $CLEANUP,%eax
testl %eax,%eax
je .L1
pushl $CLEANUP
call atexit
addl $0x4,%esp
.L1:
/* Now check to see if we have an _DYNAMIC table, and if so then
we need to register the function pointer previously in %edx, but
now conveniently saved on the stack as the argument to pass to
atexit(). */
movl $_DYNAMIC,%eax
testl %eax,%eax
je .L2
call atexit
.L2:
/* Register _fini() with atexit(). We will take care of calling _init()
directly. */
pushl $_fini
call atexit
#ifdef GCRT1
/* Start profiling. */
pushl %ebp
movl %esp,%ebp
pushl $_etext
pushl $_start
call monstartup
addl $8,%esp
popl %ebp
#endif
/* Compute the address of the environment vector on the stack and load
it into the global variable _environ. Currently argc is at 8 off
the frame pointer. Fetch the argument count into %eax, scale by the
size of each arg (4 bytes) and compute the address of the environment
vector which is 16 bytes (the two zero words we pushed, plus argc,
plus the null word terminating the arg vector) further up the stack,
off the frame pointer (whew!). */
movl 8(%ebp),%eax
leal 16(%ebp,%eax,4),%edx
movl %edx,_environ
/* Push the environment vector pointer, the argument vector pointer,
and the argument count on to the stack to set up the arguments
for _init(), _fpstart(), and main(). Note that the environment
vector pointer and the arg count were previously loaded into
%edx and %eax respectively. The only new value we need to compute
is the argument vector pointer, which is at a fixed address off
the initial frame pointer. */
/* Make sure the stack is properly aligned. */
andl $0xfffffff0,%esp
subl $4,%esp
pushl %edx
leal 12(%ebp),%edx
pushl %edx
pushl %eax
/* Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and
main(argc, argv, environ). */
call _init
call __fpstart
call main
/* Pop the argc, argv, and environ arguments off the stack, push the
value returned from main(), and call exit(). */
addl $12,%esp
pushl %eax
call exit
/* An inline equivalent of _exit, as specified in Figure 3-26 of the ABI. */
pushl $0x0
movl $0x1,%eax
lcall $7,$0
/* If all else fails, just try a halt! */
hlt
.type _start,@function
.size _start,.-_start
#ifndef GCRT1
/* A dummy profiling support routine for non-profiling executables,
in case we link in some objects that have been compiled for profiling. */
.weak _mcount
_mcount:
ret
.type _mcount,@function
.size _mcount,.-_mcount
#endif
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