mes/lib/linux/x86_64-mes-gcc/mini.c

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/* -*-comment-start: "//";comment-end:""-*-
* GNU Mes --- Maxwell Equations of Software
* Copyright © 2016,2017,2018 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/>.
*/
#define SYS_exit "0x3c"
#define SYS_write "0x01"
void
_exit (int code)
{
asm (
"mov $"SYS_exit",%%rax\n\t"
"mov %0,%%rdi\n\t"
"syscall \n\t"
: // no outputs "=" (r)
: "rm" (code)
);
// not reached
_exit (0);
}
ssize_t
_write (int filedes, void const *buffer, size_t size)
{
long r;
asm (
"mov $"SYS_write",%%rax\n\t"
"mov %1,%%rdi\n\t"
"mov %2,%%rsi\n\t"
"mov %3,%%rdx\n\t"
"syscall \n\t"
"mov %%rax,%0\n\t"
: "=r" (r)
: "rm" (filedes), "rm" (buffer), "rm" (size)
: "rax", "rdi", "rsi", "rdx"
);
return r;
}