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/* Startup code compliant to the ELF m68k ABI.
Copyright (C) 1996-2023 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
In addition to the permissions in the GNU Lesser General Public
License, the Free Software Foundation gives you unlimited
permission to link the compiled version of this file with other
programs, and to distribute those programs without any restriction
coming from the use of this file. (The GNU Lesser General Public
License restrictions do apply in other respects; for example, they
cover modification of the file, and distribution when not linked
into another program.)
Note that people who make modified versions of this file are not
obligated to grant this special exception for their modified
versions; it is their choice whether to do so. The GNU Lesser
General Public License gives permission to release a modified
version without this exception; this exception also makes it
possible to release a modified version which carries forward this
exception.
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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<https://www.gnu.org/licenses/>. */
/* This is the canonical entry point, usually the first thing in the text
segment. The SVR4/m68k ABI says that when the entry point runs,
most registers' values are unspecified, except for:
%a1 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(%sp) argc
4(%sp) argv[0]
...
(4*argc)(%sp) NULL
(4*(argc+1))(%sp) envp[0]
...
NULL
*/
#include <sysdep.h>
.text
.globl _start
.type _start,@function
_start:
/* Clear the frame pointer. The ABI suggests this be done, to mark
the outermost frame obviously. */
sub.l %fp, %fp
/* Extract the arguments as encoded on the stack and set up the
arguments for `main': argc, argv. envp will be determined
later in __libc_start_main. */
move.l (%sp)+, %d0 /* Pop the argument count. */
move.l %sp, %a0 /* The argument vector starts just at the
current stack top. */
/* Provide the highest stack address to the user code (for stacks
which grow downward). */
pea (%sp)
pea (%a1) /* Push address of the shared library
termination function. */
/* These used to be addresses of the .fini and .init entry points. */
clr.l -(%sp)
clr.l -(%sp)
#ifdef PIC
/* Load PIC register. */
LOAD_GOT (%a5)
pea (%a0) /* Push second argument: argv. */
move.l %d0, -(%sp) /* Push first argument: argc. */
move.l main@GOT(%a5), -(%sp)
/* Call the user's main function, and exit with its value. But
let the libc call main. */
jbsr __libc_start_main@PLTPC
#else
pea (%a0) /* Push second argument: argv. */
move.l %d0, -(%sp) /* Push first argument: argc. */
pea main
/* Call the user's main function, and exit with its value. But
let the libc call main. */
jbsr __libc_start_main
#endif
illegal /* Crash if somehow `exit' does return. */
/* 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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