diff --git a/Makefile b/Makefile
index 5829d0b..0fc454c 100644
--- a/Makefile
+++ b/Makefile
@@ -28,6 +28,7 @@ LIBSRC = uart_init_.c uart_send_chr.c uart_send_str.c \
 	long_tobcd__.c long_tobcd.c \
 	bcd_tolong__.c bcd_tolong.c \
 	long_addbyte__.c long_addbyte.c \
+	long_add__.c long_add.c \
 	long_1cpl__.c long_invert__.c long_invert.c
 
 
diff --git a/long_add.c b/long_add.c
index b80ebd6..739c157 100644
--- a/long_add.c
+++ b/long_add.c
@@ -9,23 +9,17 @@ uint8_t long_add(__idata uint8_t *v1, __idata uint8_t *v2,uint8_t len) __reentra
 	__asm
 	mov	a,_bp
 	add	a,#0xfd
-	mov	sp,a
-	pop	ar1
-	pop	ar7
-	mov	ar0,dpl
-	clr c
-001$:		
-	mov	a,@r0
-	addc	a,@r1
-	mov	@r0,a
-	inc	r0
-	inc	r1
-	djnz	r7,001$
+	mov	r0,a
+	mov	a,@r0		; *v2
+	mov	r1,a
+	mov	a,@r0		; len
+	mov	r7,a		
+	mov	r0,dpl
+	lcall	long_invert
 	mov	dpl,#0x00
 	jnc	$002
 	inc	dpl
 $002:
-	mov	sp,_bp
 	__endasm;
 }
 
diff --git a/long_add__.c b/long_add__.c
new file mode 100644
index 0000000..3a64965
--- /dev/null
+++ b/long_add__.c
@@ -0,0 +1,25 @@
+/*
+ * @r0 = @r0+@r1
+ * r7=len
+ */
+
+static void long_add__() __naked
+{
+	__asm
+long_add:
+	clr	c
+long_addc:
+001$:		
+	mov	a,@r0
+	addc	a,@r1
+	mov	@r0,a
+	inc	r0
+	inc	r1
+	djnz	r7,001$
+	ret
+
+	__endasm;
+}
+
+
+
diff --git a/mc8051fun.h b/mc8051fun.h
index 71ac0e2..a3e8767 100644
--- a/mc8051fun.h
+++ b/mc8051fun.h
@@ -90,6 +90,7 @@ uint8_t multest(uint8_t a, uint8_t b);
 
 void bcd_tolong(__idata uint8_t *bcdval, __idata uint8_t *binval, uint8_t bcdlen, uint8_t binlen) __reentrant;
 void long_invert(__idata uint8_t *val, uint8_t len) __reentrant;
+uint8_t long_add(__idata uint8_t *v1, __idata uint8_t *v2,uint8_t len) __reentrant;
 
 
 #endif