usys.s

; System call numbers
%define SYS_fork    1
%define SYS_exit    2
%define SYS_waitt    3
%define SYS_pipe    4
%define SYS_read    5
%define SYS_kill    6
%define SYS_exec    7
%define SYS_fstat   8
%define SYS_chdir   9
%define SYS_dup    10
%define SYS_getpid 11
%define SYS_sbrk   12
%define SYS_sleep  13
%define SYS_uptime 14
%define SYS_open   15
%define SYS_write  16
%define SYS_mknod  17
%define SYS_unlink 18
%define SYS_link   19
%define SYS_mkdir  20
%define SYS_close  21

%macro SYSCALL 1
global %1
%1:
	mov eax, SYS_%1
	int 64 ; 64 is system call
	ret
%endmacro

SYSCALL write
SYSCALL fork
SYSCALL exec
SYSCALL read
SYSCALL sbrk
SYSCALL waitt
SYSCALL exit