// System call numbers
#define SYS_fork 1
#define SYS_exit 2
#define SYS_wait 3
#define SYS_pipe 4
#define SYS_write 5
#define SYS_read 6
#define SYS_close 7
#define SYS_kill 8
#define SYS_exec 9
#define SYS_open 10
#define SYS_mknod 11
#define SYS_unlink 12
#define SYS_fstat 13
#define SYS_link 14
#define SYS_mkdir 15
#define SYS_chdir 16
#define SYS_dup 17
#define SYS_getpid 18
#define SYS_sbrk 19
