diff --git a/ucore/src/arch/x86_64/arch.h b/ucore/src/arch/x86_64/arch.h
index b5e7011..a087a74 100644
--- a/ucore/src/arch/x86_64/arch.h
+++ b/ucore/src/arch/x86_64/arch.h
@@ -3,20 +3,13 @@
 
 #include <defs.h>
 
-#define do_div(n, base) ({                                          \
-            unsigned long __upper, __low, __high, __mod, __base;    \
-            __base = (base);                                        \
-            asm ("" : "=a" (__low), "=d" (__high) : "A" (n));       \
-            __upper = __high;                                       \
-            if (__high != 0) {                                      \
-                __upper = __high % __base;                          \
-                __high = __high / __base;                           \
-            }                                                       \
-            asm ("divl %2" : "=a" (__low), "=d" (__mod)             \
-                : "rm" (__base), "0" (__low), "1" (__upper));       \
-            asm ("" : "=A" (n) : "a" (__low), "d" (__high));        \
-            __mod;                                                  \
-        })
+# define do_div(n,base) ({					\
+	uint32_t __base = (base);				\
+	uint32_t __rem;						\
+	__rem = ((uint64_t)(n)) % __base;			\
+	(n) = ((uint64_t)(n)) / __base;				\
+	__rem;							\
+ })
 
 #define barrier() __asm__ __volatile__ ("" ::: "memory")
 
diff --git a/ucore/src/mandelbrot.c b/ucore/src/mandelbrot.c
index 232a40c..1617476 100644
--- a/ucore/src/mandelbrot.c
+++ b/ucore/src/mandelbrot.c
@@ -9,15 +9,17 @@
 #if defined(__x86_64__)
 #define WIDTH 1024
 #define HEIGHT 768
+#define BPP 3
 #else
 #define WIDTH 800
 #define HEIGHT 600
+#define BPP 1
 #endif
 
-char buf[WIDTH];
+char buf[WIDTH * BPP];
 
 volatile char* frame_buf = (volatile char*) 0xA2000000;
-int w = WIDTH, h = HEIGHT, x, y;
+int w = WIDTH, h = HEIGHT, x, y, i;
 //each iteration, it calculates: newz = oldz*oldz + p, where p is the current pixel, and oldz stars at the origin
 float pr, pi; //real and imaginary part of the pixel p
 float newRe, newIm, oldRe, oldIm; //real and imaginary parts of new and old z
@@ -29,13 +31,15 @@ void plot(float moveX, float moveY, float zoom, int maxIterations, int skip) {
     volatile char *line_addr = frame_buf;
     for (y = 0; y < h; y++) {
         if (y % skip) {
-            memcpy(line_addr, line_addr - WIDTH, WIDTH);
-            line_addr += WIDTH;
+            memcpy(line_addr, line_addr - WIDTH * BPP, WIDTH * BPP);
+            line_addr += WIDTH * BPP;
             continue;
         }
         for (x = 0; x < w; x++) {
             if (x % skip) {
-                buf[x] = buf[x - 1];
+                for (i = 0;i < BPP;i++) {
+                    buf[x * BPP + i] = buf[(x - 1) * BPP + i];
+                }
                 continue;
             }
             // calculate the initial real and imaginary part of z, based on the pixel location and zoom and position values
@@ -59,17 +63,19 @@ void plot(float moveX, float moveY, float zoom, int maxIterations, int skip) {
 
             int color = i * 255 / maxIterations;
 
-            buf[x] = (color << 5) | (color << 2) | (color >> 1);
+            for (i = 0;i < BPP;i++) {
+                buf[x * BPP + i] = (color << 5) | (color << 2) | (color >> 1);
+            }
         }
-        memcpy(line_addr, buf, WIDTH);
-        line_addr += WIDTH;
+        memcpy(line_addr, buf, WIDTH * BPP);
+        line_addr += WIDTH * BPP;
     }
 }
 
 int main(void) {
 #if defined(__x86_64__)
     int fd = sys_open("/dev/fb0", O_WRONLY);
-    frame_buf = (volatile char *)sys_mmap(0, WIDTH * HEIGHT * 3, PROT_WRITE, 0, fd, 0);
+    frame_buf = (volatile char *)sys_mmap(0, WIDTH * HEIGHT * BPP, PROT_WRITE, 0, fd, 0);
 #endif
     float zoom = 1, moveX = -0.5, moveY = 0; //you can change these to zoom and change position
     int maxIterations = 255; //after how much iterations the function should stop