diff --git a/include/framebuffer.h b/include/framebuffer.h
new file mode 100644
index 0000000..a6c36d8
--- /dev/null
+++ b/include/framebuffer.h
@@ -0,0 +1,11 @@
+#ifndef __INCLUDE_FRAMEBUFFER_H__
+#define __INCLUDE_FRAMEBUFFER_H__
+
+#include <stdint.h>
+
+void fb_draw_pixel(uint16_t *image, uint16_t x, uint16_t y, uint16_t color);
+void fb_draw_line(uint16_t *image, int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color);
+void fb_load_image(uint16_t *dst, uint16_t *src, uint32_t length);
+void fb_set_image(uint16_t *dst, uint16_t value, uint32_t length);
+
+#endif
\ No newline at end of file
diff --git a/src/framebuffer.c b/src/framebuffer.c
new file mode 100644
index 0000000..661ca8a
--- /dev/null
+++ b/src/framebuffer.c
@@ -0,0 +1,77 @@
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+#include "framebuffer.h"
+
+void fb_draw_pixel(uint16_t *image, uint16_t x, uint16_t y, uint16_t color)
+{
+    assert(image != NULL);
+
+    image[x + 240 * y] = color;
+}
+
+#ifndef _swap_int16_t
+#define _swap_int16_t(a, b) { int16_t t = a; a = b; b = t; }
+#endif
+
+void fb_draw_line(uint16_t *image, int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color)
+{
+    assert(image != NULL);
+
+    int16_t steep = abs(y1 - y0) > abs(x1 - x0);
+    if(steep) {
+        _swap_int16_t(x0, y0);
+        _swap_int16_t(x1, y1);
+    }
+    if(x0 > x1) {
+        _swap_int16_t(x0, x1);
+        _swap_int16_t(y0, y1);
+    }
+
+    int16_t dx, dy;
+    dx = x1 - x0;
+    dy = abs(y1 - y0);
+
+    int16_t err = dx / 2;
+    int16_t ystep;
+
+    if(y0 < y1) {
+        ystep = 1;
+    } else {
+        ystep = -1;
+    }
+
+    for(; x0 <= x1; x0++) {
+        if(steep) {
+            fb_draw_pixel(image, y0, x0, color);
+        } else {
+            fb_draw_pixel(image, x0, y0, color);
+        }
+        err -= dy;
+        if (err < 0) {
+            y0 += ystep;
+            err += dx;
+        }
+    }
+}
+
+void fb_load_image(uint16_t *dst, uint16_t *src, uint32_t length)
+{
+    assert(NULL != dst);
+    assert(NULL != src);
+
+    for(uint32_t i = 0; i < length; i++) {
+        dst[i] = src[i];
+    }
+}
+
+void fb_set_image(uint16_t *dst, uint16_t value, uint32_t length)
+{
+    assert(NULL != dst);
+
+    for (uint32_t i = 0; i < length; i++) {
+        dst[i] = value;
+    }
+}
+
diff --git a/src/main.c b/src/main.c
index fbb6506..c698956 100644
--- a/src/main.c
+++ b/src/main.c
@@ -9,75 +9,10 @@
 #include "board.h"
 #include "driver.h"
 #include "clock_face.h"
+#include "framebuffer.h"
 
 uint16_t image[240 * 240];
 
-static void bmp_draw_pixel(uint16_t *image, uint16_t x, uint16_t y, uint16_t color)
-{
-    assert(image != NULL);
-
-    image[x + 240 * y] = color;
-}
-
-#ifndef _swap_int16_t
-#define _swap_int16_t(a, b) { int16_t t = a; a = b; b = t; }
-#endif
-
-static void img_draw_line(uint16_t *image, int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color)
-{
-    assert(image != NULL);
-
-    int16_t steep = abs(y1 - y0) > abs(x1 - x0);
-    if(steep) {
-        _swap_int16_t(x0, y0);
-        _swap_int16_t(x1, y1);
-    }
-    if(x0 > x1) {
-        _swap_int16_t(x0, x1);
-        _swap_int16_t(y0, y1);
-    }
-
-    int16_t dx, dy;
-    dx = x1 - x0;
-    dy = abs(y1 - y0);
-
-    int16_t err = dx / 2;
-    int16_t ystep;
-
-    if(y0 < y1) {
-        ystep = 1;
-    } else {
-        ystep = -1;
-    }
-
-    for(; x0 <= x1; x0++) {
-        if(steep) {
-            bmp_draw_pixel(image, y0, x0, color);
-        } else {
-            bmp_draw_pixel(image, x0, y0, color);
-        }
-        err -= dy;
-        if (err < 0) {
-            y0 += ystep;
-            err += dx;
-        }
-    }
-}
-
-static void img_load(uint16_t *dst, uint16_t *src, uint32_t length)
-{
-    for(uint32_t i = 0; i < length; i++) {
-        dst[i] = src[i];
-    }
-}
-
-static void img_set(uint16_t *dst, uint16_t value, uint32_t length)
-{
-    for (uint32_t i = 0; i < length; i++) {
-        image[i] = value;
-    }
-}
-
 int main(void)
 {
     drv_open(&lcd_drv);
@@ -95,12 +30,12 @@ int main(void)
     struct  tm tm;
 
     while(1) {
-        img_load(image, clock_face, 240 * 240);
+        fb_load_image(image, clock_face, 240 * 240);
 
         // just to shown image orientation
-        img_draw_line(image, 10, 10, 12, 12, 0x00f8);
-        img_draw_line(image, 10, 11, 12, 12, 0x00f8);
-        img_draw_line(image, 10, 12, 12, 12, 0x00f8);
+        fb_draw_line(image, 10, 10, 12, 12, 0x00f8);
+        fb_draw_line(image, 10, 11, 12, 12, 0x00f8);
+        fb_draw_line(image, 10, 12, 12, 12, 0x00f8);
 
         T = time(NULL);
         tm = *localtime(&T);
@@ -112,7 +47,7 @@ int main(void)
 
         dest_x = root_x + min_len * cos(min_angle * M_PI / 180);
         dest_y = root_y + min_len * sin(min_angle * M_PI / 180);
-        img_draw_line(image, (uint16_t)root_x, (uint16_t)root_y, (uint16_t)dest_x, (uint16_t)dest_y, 0xffff);
+        fb_draw_line(image, (uint16_t)root_x, (uint16_t)root_y, (uint16_t)dest_x, (uint16_t)dest_y, 0xffff);
 
         std_angle = 0.5 * (60 * tm.tm_hour + tm.tm_min);
         if(std_angle >= 360.0) {
@@ -121,7 +56,7 @@ int main(void)
 
         dest_x = root_x + std_len * cos(std_angle * M_PI / 180);
         dest_y = root_y + std_len * sin(std_angle * M_PI / 180);
-        img_draw_line(image, (uint16_t)root_x, (uint16_t)root_y, (uint16_t)dest_x, (uint16_t)dest_y, 0xffff);
+        fb_draw_line(image, (uint16_t)root_x, (uint16_t)root_y, (uint16_t)dest_x, (uint16_t)dest_y, 0xffff);
 
         drv_write(&lcd_drv, (const char *)image, 240 * 240);
         sleep(1);