why am i getting these syntax errors when trying to implement system call - operating-system

Question

still working on this system call!!!
i have added a system call to a kernel, compiled and the OS is running off it.
now i am getting syntax error on the compilation of my test application.
testmycall.h
#include<linux/unistd.h>
#define __NR_mycall 244
_syscall1(long, mycall, int, i)
testmycall.c
#include<stdio.h>
#include "testmycall.h"
int main(int argc, char *argv[])
{
printf("%d\n", mycall(15));
}
here is the error
stef#ubuntu:~$ gcc -o testmycall testmycall.c
In file included from testmycall.c:3:
testmycall.h:7: error: expected ‘)’ before ‘mycall’
stef#ubuntu:~$ gcc -o testmycall testmycall.c
In file included from testmycall.c:3:
testmycall.h:7: error: expected declaration specifiers or ‘...’ before ‘mycall’
testmycall.h:7: error: expected declaration specifiers or ‘...’ before ‘i’
testmycall.c: In function ‘_syscall1’:
testmycall.c:7: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token
testmycall.h:7: error: parameter name omitted
testmycall.h:7: error: parameter name omitted
testmycall.c:11: error: expected ‘{’ at end of input
stef#ubuntu
i have added in the syscall instead of _syscall1
now i get this error
stef#ubuntu:~$ gcc -o testmycall testmycall.c
testmycall.c: In function ‘syscall’:
testmycall.c:7: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token
testmycall.c:11: error: expected ‘{’
this is the app, any ideas why???

Answer 1

I believe the _syscallN() macros were removed from the kernel headers around 2.6.18 or so.
The (not especially helpful) error messages from gcc are due to _syscall1 not being defined at all - you get the same errors if you write:
any_old_rubbish_here(long, mycall, int, i)
The syscall() function should work. man syscall for details.

Answer 2

The _syscall macros are obsolete and should not be used, instead use syscall, eg.
#define _GNU_SOURCE
#include <unistd.h>
...
printf("%d\n", syscall(__NR_mycall, 15));
Here's my test program:
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#define __NR_mycall 244
int main(int argc, char **argv)
{
printf("%d\n", syscall(__NR_mycall,15));
return 0;
}