62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
|
/* -*-comment-start: "//";comment-end:""-*-
|
||
|
|
* Mes --- Maxwell Equations of Software
|
||
|
|
* Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
|
||
|
|
*
|
||
|
|
* This file is part of Mes.
|
||
|
|
*
|
||
|
|
* 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.
|
||
|
|
*
|
||
|
|
* 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 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
|
||
|
|
|
||
|
|
char **environ = 0;
|
||
|
|
int _main (int argc, char *argv[]);
|
||
|
|
|
||
|
|
void
|
||
|
|
_start ()
|
||
|
|
{
|
||
|
|
asm (
|
||
|
|
"mov %%ebp,%%eax\n\t"
|
||
|
|
"addl $4,%%eax\n\t"
|
||
|
|
"movzbl (%%eax),%%eax\n\t"
|
||
|
|
"addl $3,%%eax\n\t"
|
||
|
|
"shl $2,%%eax\n\t"
|
||
|
|
"add %%ebp,%%eax\n\t"
|
||
|
|
"movl %%eax,%0\n\t"
|
||
|
|
: "=environ" (environ)
|
||
|
|
: //no inputs ""
|
||
|
|
);
|
||
|
|
asm (
|
||
|
|
"mov %%ebp,%%eax\n\t"
|
||
|
|
"addl $8,%%eax\n\t"
|
||
|
|
"push %%eax\n\t"
|
||
|
|
|
||
|
|
"mov %%ebp,%%eax\n\t"
|
||
|
|
"addl $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"
|
||
|
|
:
|
||
|
|
);
|
||
|
|
}
|