diff --git a/.gitignore b/.gitignore
index 8831380..4b37343 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .objs
 test
 libasm.a
+libasm_bonus.a
diff --git a/Makefile b/Makefile
index e7635ef..031261c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,25 +1,33 @@
 NAME ?= libasm.a
 
 SRCS_DIR = srcs
+SRCS_BONUS_DIR = srcs/bonus
 OBJS_DIR = .objs
 
-SRCS_NAMES =	ft_strlen.s\
-	   			ft_strcpy.s\
-	   			ft_strcmp.s\
-	   			ft_write.s\
-	   			ft_read.s\
-	   			ft_strdup.s
+SRCS_NAMES =		ft_strlen.s\
+	   				ft_strcpy.s\
+	   				ft_strcmp.s\
+	   				ft_write.s\
+	   				ft_read.s\
+	   				ft_strdup.s
+
+SRCS_BONUS_NAMES = 	ft_atoi_base.s
 
 SRCS = $(addprefix $(SRCS_DIR)/, $(SRCS_NAMES))
+SRCS_BONUS = $(addprefix $(SRCS_BONUS_DIR)/, $(SRCS_NAMES))
 
 OBJS = $(addprefix $(OBJS_DIR)/, $(SRCS_NAMES:.s=.o))
+OBJS_BONUS = $(addprefix $(OBJS_DIR)/, $(SRCS_BONUS_NAMES:.s=.o))
 
 FLAGS = -felf64
 
 all: $(NAME)
+
+libasm_bonus.a : $(OBJS_DIR) $(OBJS) $(OBJS_BONUS)
+	ar rcs libasm_bonus.a $(OBJS) $(OBJS_BONUS)
 	
-test: test.c $(NAME)
-	clang -z noexecstack test.c -L. -lasm  -o test -g
+test: test.c libasm_bonus.a
+	clang -z noexecstack test.c -L. -lasm_bonus  -o test -g
 
 $(NAME): $(OBJS_DIR) $(OBJS)
 	ar rcs $@ $(OBJS)
@@ -30,6 +38,9 @@ $(OBJS_DIR):
 $(OBJS_DIR)/%.o: $(SRCS_DIR)/%.s
 	nasm $(FLAGS) -o $@ $<
 
+$(OBJS_DIR)/%.o: $(SRCS_BONUS_DIR)/%.s
+	nasm $(FLAGS) -o $@ $<
+
 clean:
 	rm -rf $(OBJS_DIR)
 
diff --git a/README.md b/README.md
index 4817d3f..35a5565 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ While doing this project, since I had never programmed in x86_64 assembly before
 I mostly had trouble with remembering the order of the functions parameters in the registers, I kept going back to 
 [this stackoverflow thread](https://stackoverflow.com/questions/13901261/calling-assembly-function-from-c)
 provided the order I needed. And in this thread I found information about the System V calling convention.
+The order I needed was : rdi, rsi, rdx, rcx, r8, r9
 
 During this project, I also needed to make system calls. To their parameters and numbers, I used [this page](https://blog.rchapman.org/posts/Linux_System_Call_Table_for_x86_64/) which has a table of all the system calls.
 
diff --git a/srcs/bonus/ft_atoi_base.s b/srcs/bonus/ft_atoi_base.s
new file mode 100644
index 0000000..ef71c63
--- /dev/null
+++ b/srcs/bonus/ft_atoi_base.s
@@ -0,0 +1,63 @@
+; atoi base
+; prototype : int ft_atoi_base(char *str, char *base)
+
+;global ft_atoi_base
+global get_char_index 
+global check_base
+
+section .data
+invalid_chars: db "+- ", 0x0c, 0x0a, 0x0d, 0x09, 0x0b, 0
+
+section .text
+
+; checks if a char is in the invalid_chars
+get_char_index: 
+	xor rax, rax
+	push rsi
+
+get_char_index_loop:
+	cmp dil, [rsi] ;is char invalid
+	je get_char_index_found 
+
+	mov al, [rsi] ; is end of string
+	test al, al
+	lea rsi, [rsi + 1]
+	jne get_char_index_loop 
+
+	xor rax, -1 ;not found and at the end
+	pop rsi
+	ret
+
+get_char_index_found:
+	pop rax ;return index of the found char
+	sub rsi, rax
+	mov rax, rsi 
+	ret
+
+;function that checks if the base is valid
+;a valid base does not have any of these char : "+-" or any space defined by isspace(3) and does not have any duplicate char
+; returns 0 if base is not valid
+check_base:
+	xor rax, rax
+
+chk_bs_char:
+	mov al, [rdi] ; if rdi is \0, return 0
+	test al, al
+	je base_ok 
+
+	push rdi ; if current char is in invalid_chars
+	mov dil, [rdi];
+	lea rsi, [rel invalid_chars]
+	call get_char_index 
+	pop rdi
+
+	cmp rax, -1 ; if not -1, error
+	lea rdi, [rdi + 1]
+	je chk_bs_char
+
+	xor rax, rax; return 0
+	ret
+
+base_ok:
+	mov rax,1
+	ret
diff --git a/test.c b/test.c
index 2f927f3..012c645 100644
--- a/test.c
+++ b/test.c
@@ -6,7 +6,7 @@
 /*   By: tomoron <tomoron@student.42angouleme.fr>   +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2025/03/29 19:53:58 by tomoron           #+#    #+#             */
-/*   Updated: 2025/03/30 15:55:13 by tomoron          ###   ########.fr       */
+/*   Updated: 2025/03/31 16:42:55 by tomoron          ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -180,6 +180,21 @@ int test_strdup(void)
 	return(nb_tests == passed);
 }
 
+size_t	check_base(char *base);
+int tmp(void)
+{
+	int nb_tests;
+	int passed;
+
+	nb_tests = 4;
+	passed = 0;
+
+	TEST("a", check_base("a") == 1);
+	TEST("a", check_base("abcdef") == 1);
+
+	return(nb_tests == passed);
+}
+
 int main(void)
 {
 	FNC_TEST("ft_strlen", test_strlen());
@@ -193,4 +208,6 @@ int main(void)
 	FNC_TEST("ft_read", test_read());
 	printf("\n\n");
 	FNC_TEST("ft_strdup", test_strdup());
+	printf("\n\n");
+	FNC_TEST("tmp", tmp());
 }