1 /* Startup code compliant to the ELF m68k ABI.
2 Copyright (C) 1996, 1997, 1998, 2001 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
20 /* This is the canonical entry point, usually the first thing in the text
21 segment. The SVR4/m68k ABI says that when the entry point runs,
22 most registers' values are unspecified, except for:
24 %a1 Contains a function pointer to be registered with `atexit'.
25 This is how the dynamic linker arranges to have DT_FINI
26 functions called for shared libraries that have been loaded
27 before this code runs.
29 %sp The stack contains the arguments and environment:
34 (4*(argc+1))(%sp) envp[0]
41 .type _start,@function
43 /* Clear the frame pointer. The ABI suggests this be done, to mark
44 the outermost frame obviously. */
47 /* Extract the arguments as encoded on the stack and set up the
48 arguments for `main': argc, argv. envp will be determined
49 later in __libc_start_main. */
50 move.l (%sp)+, %d0 /* Pop the argument count. */
51 move.l %sp, %a0 /* The argument vector starts just at the
54 /* Provide the highest stack address to the user code (for stacks
55 which grow downward). */
58 pea (%a1) /* Push address of the shared library
59 termination function. */
61 /* Push the address of our own entry points to `.fini' and
66 pea (%a0) /* Push second argument: argv. */
67 move.l %d0, -(%sp) /* Push first argument: argc. */
71 /* Call the user's main function, and exit with its value. But
72 let the libc call main. */
73 jbsr __libc_start_main
75 illegal /* Crash if somehow `exit' does return. */
77 /* Define a symbol for the first piece of initialized data. */
83 data_start = __data_start