mes/lib/linux/x86-mes-gcc/crt0.c

62 lines
1.7 KiB
C

/* -*-comment-start: "//";comment-end:""-*-
* GNU Mes --- Maxwell Equations of Software
* Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
*
* This file is part of GNU Mes.
*
* GNU Mes 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 of the License, or (at
* your option) any later version.
*
* GNU Mes 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.
*
* You should have received a copy of the GNU General Public License
* along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
*/
// no clue what crt0.o is and why gcc-2.6.3 needs it
// instead of calling main, it seems to call either _main or ___main,
// let's try _main first
#include <mes/lib-mini.h>
int _main (int argc, char *argv[]);
// *INDENT-OFF*
void
_start ()
{
asm (
"mov %%ebp,%%eax\n\t"
"add $4,%%eax\n\t"
"movzbl (%%eax),%%eax\n\t"
"add $3,%%eax\n\t"
"shl $2,%%eax\n\t"
"add %%ebp,%%eax\n\t"
"mov %%eax,%0\n\t"
: "=r" (environ)
: //no inputs ""
);
asm (
"mov %ebp,%eax\n\t"
"add $8,%eax\n\t"
"push %eax\n\t"
"mov %ebp,%eax\n\t"
"add $4,%eax\n\t"
"movzbl (%eax),%eax\n\t"
"push %eax\n\t"
"call _main\n\t"
"mov %eax,%ebx\n\t"
"mov $1,%eax\n\t"
"int $0x80\n\t"
"hlt \n\t"
);
}