diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..f9f383e
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,44 @@
+SHELL = bash
+
+# --- lib ---
+
+NAME = libasm.a
+
+OBJ_DIR = obj/
+SRC_DIR = src/
+SRC = $(shell find $(SRC_DIR) -name '*.s')
+OBJ = $(addprefix $(OBJ_DIR), $(SRC:.s=.o))
+
+AS = nasm
+ASFLAGS = -f elf64
+
+# --- tester ---
+
+t_CC = gcc
+t_CFLAGS = -z noexecstack
+t_SRC = src/tests/main.c
+t_NAME = tester
+
+all: $(NAME)
+
+$(NAME): $(OBJ)
+	ar rcs -o $@ $(OBJ)
+
+$(OBJ_DIR)%.o: %.s
+	@mkdir -p $(@D)
+	$(AS) $(ASFLAGS) $< -o $@
+
+clean:
+	rm -rf $(OBJ_DIR)
+
+
+fclean: clean
+	rm $(NAME)
+
+re: fclean
+	$(MAKE) -s all
+
+test: $(OBJ)
+	$(t_CC) $(OBJ) $(t_SRC) $(t_CFLAGS) -o $(t_NAME)
+
+.PHONY: clean fclean all re
diff --git a/src/str/ft_strcmp.s b/src/str/ft_strcmp.s
index 03097fb..29666ff 100644
--- a/src/str/ft_strcmp.s
+++ b/src/str/ft_strcmp.s
@@ -9,11 +9,13 @@ ft_strcmp:
 	cmp		rsi, 0
 	je		.ret
 
+	mov		rax, rdi
+
 .loop:
 
 	mov		r10b, BYTE [rdi]
 	cmp		r10b, BYTE [rsi]
-	je		.end
+	jne		.end
 
 	cmp		BYTE [rdi], 0
 	je		.end
@@ -25,8 +27,11 @@ ft_strcmp:
 	jmp		.loop
 
 .end:
-	mov	al, BYTE [rsi]
-	mov	r10b, BYTE [rdi]
+	movzx	rax, BYTE [rdi]
+	movzx	r10, BYTE [rsi]
 	sub		rax, r10
+
+	;sub		rdi, rax
+	;mov		rax, rdi
 .ret:
 	ret
diff --git a/src/sys/ft_write.s b/src/sys/ft_write.s
new file mode 100644
index 0000000..f390cf9
--- /dev/null
+++ b/src/sys/ft_write.s
@@ -0,0 +1,22 @@
+extern __errno_location
+
+section .text
+global ft_write
+
+; ssize_t write(int fd, const void *buf, size_t count);
+ft_write:
+	mov		eax, 1
+	syscall
+
+	cmp		rax, 0
+	jle		.error
+
+.ret:
+	ret
+
+.error:
+	mov		r10, rax
+	call	__errno_location wrt ..plt
+	mov		[rax], r10
+	mov		rax, -1
+	jmp		.ret
diff --git a/src/str/main.c b/src/tests/main.c
similarity index 55%
rename from src/str/main.c
rename to src/tests/main.c
index e01a185..ce8922d 100644
--- a/src/str/main.c
+++ b/src/tests/main.c
@@ -1,8 +1,10 @@
 int		ft_strlen(char *str);
 char	*ft_strcpy(char *dest, const char *src);
 int		ft_strcmp(const char *s1, const char *s2);
+int		ft_write(int fd, const char *buf, unsigned int count);
 
 #include <stdio.h>
+#include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -20,11 +22,20 @@ int	main(void)
 	printf("arg : \"abcdefgh\" | result : %s\n", strcpy(a2, "abcdefgh"));
 	printf("arg : \"67\" | result : %s\n", ft_strcpy(a1, "67"));
 	printf("arg : \"67\" | result : %s\n", strcpy(a2, "67"));
-	printf("arg : \"aaa\" (dest = NULL) | result : %s\n", ft_strcpy(NULL, "67"));
-	printf("arg : NULL | result : %s\n", ft_strcpy(a2, NULL));
+	printf("EXCEPTION : dest : NULL | result : %s\n", ft_strcpy(NULL, "67"));
+	printf("EXCEPTION : src : NULL | result : %s\n", ft_strcpy(a2, NULL));
 
 
 	printf("\n--- ft_strcmp ---\n");
 	printf("arg : \"aaaaaa\" \"aaaa\" | result : %d (expected : %d)\n", ft_strcmp("aaaaaa", "aaaa"), strcmp("aaaaaa", "aaaa"));
 	printf("arg : \"aaaa\" \"bb\" | result : %d (expected : %d)\n", ft_strcmp("aaaa", "bb"), strcmp("aaaa", "bb"));
+	printf("arg : \"i love nixos !!\" \"i love nixos !!\" | result : %d (expected : %d)\n", ft_strcmp("i love nixos !!", "i love nixos !!"), strcmp("i love nixos !!", "i love nixos !!"));
+	printf("EXCEPTION : s1 : NULL | result : %d \n", ft_strcmp(NULL, "hiiiii :D"));
+	printf("EXCEPTION : s2 : NULL | result : %d \n", ft_strcmp("hihi :3", NULL));
+
+	printf("\n--- ft_write ---\n");
+	printf("| 1 \"xd\" 2 | %d\n", ft_write(1, "xd", 2));
+	printf("| 200 \"xd\" 2 | %d\n", ft_write(200, "xd", 2));
+	int fd = open("out", O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
+	printf("| %d \"[...]\" 42 | %d\n", fd, ft_write(fd, "wizard money gang, we love casting spells\n", 42));
 }