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1.6 KiB
C

/* Copyright (C) 2025 John Törnblom
This program 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, or (at your option) any
later version.
This program 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 this program; see the file COPYING. If not, see
<http://www.gnu.org/licenses/>. */
long
__syscall(long n, ...) {
long a1 = 0, a2 = 0, a3 = 0, a4 = 0, a5 = 0, a6 = 0;
__builtin_va_list ap;
unsigned long ret;
char iserror;
__builtin_va_start(ap, n);
a1 = __builtin_va_arg(ap, long);
a2 = __builtin_va_arg(ap, long);
a3 = __builtin_va_arg(ap, long);
a4 = __builtin_va_arg(ap, long);
a5 = __builtin_va_arg(ap, long);
a6 = __builtin_va_arg(ap, long);
__builtin_va_end(ap);
register long r10 __asm__("r10") = a4;
register long r8 __asm__("r8") = a5;
register long r9 __asm__("r9") = a6;
__asm__ __volatile__("syscall"
: "=a"(ret), "=@ccc"(iserror), "+r"(r10), "+r"(r8), "+r"(r9)
: "a"(n), "D"(a1), "S"(a2), "d"(a3)
: "rcx", "r11", "memory");
return iserror ? -ret : ret;
}
int
klog(const char *s) {
return __syscall(0x259, 7, s, 0);
}
int
main(void) {
klog("Hello, world!\n");
return 0;
}
void
_start(void) {
__syscall(1, main()); // exit
__builtin_trap();
}