Improve the write_u32 method

src/screen.rs

@@ -158,37 +158,22 @@ impl<
         self.write_str(core::str::from_utf8(&buff[..=num_len]).unwrap());
     }
 
-    pub fn write_u32(&mut self, num: u32) {
-        // This function is for debugging purposes only, it does not show
-        // The 0's to the right of the number
-        // The max number in an u32 is: 4,294,967,295
-        let mut buff = [0; 10];
-        let len = num_chars(num, &mut buff);
-        self.write_str(&core::str::from_utf8(&buff[..len]).unwrap());
+    pub fn write_u32(&mut self, mut num: u32) {
+        if num == 0 {
+            self.write_char('0');
+            return;
+        }
+
+        let mut buff = [0u8; 10];
+        let num_len = num.ilog10() as usize;
+        for i in (0..=num_len).rev() {
+            buff[i] = (num % 10) as u8 + '0' as u8;
+            num /= 10;
+        }
+        self.write_str(core::str::from_utf8(&buff[..=num_len]).unwrap());
     }
 }
 
 fn last_bit(n: u8) -> bool {
     (n & 1) != 0
 }
-
-fn num_rev(mut num: u32) -> u32 {
-    let mut rev_num = 0;
-    while num > 0 {
-        let digit = num % 10;
-        rev_num = rev_num * 10 + digit;
-        num /= 10;
-    }
-    rev_num
-}
-
-fn num_chars(n: u32, output: &mut [u8]) -> usize {
-    let mut n = num_rev(n);
-    let mut i = 0;
-    while n > 0 {
-        output[i] = (n % 10) as u8 + '0' as u8;
-        n = n / 10;
-        i += 1;
-    }
-    i
-}