Fix Bit_Length Will Revert if Input Most

Significant Bit Is 1

src/utils/bitwise.cairo

@@ -49,24 +49,25 @@ fn right_shift<
 fn bit_length<
     T,
     impl TZeroable: Zeroable<T>,
-    impl TPartialOrd: PartialOrd<T>,
-    impl TAddImpl: Add<T>,
-    impl TSub: Sub<T>,
-    impl TMul: Mul<T>,
     impl TOneable: Oneable<T>,
+    impl TPartialEq: PartialEq<T>,
+    impl TAddImpl: Add<T>,
+    impl TDiv: Div<T>,
     impl TCopy: Copy<T>,
     impl TDrop: Drop<T>
 >(
     num: T
 ) -> T {
     let mut bit_position = TZeroable::zero();
-    let mut cur_n = TOneable::one();
+    let mut cur_n = num;
+    let two = TOneable::one() + TOneable::one();
+
     loop {
-        if cur_n > num {
+        if cur_n == TZeroable::zero() {
             break ();
         };
         bit_position = bit_position + TOneable::one();
-        cur_n = left_shift(cur_n, TOneable::one());
+        cur_n = cur_n / two;
     };
     bit_position
 }

src/utils/tests/test_bitwise.cairo

@@ -33,3 +33,8 @@ fn test_bit_length() {
     assert(bit_length(8_u32) == 4, 'bit length of 8 is 4');
 }
 
+#[test]
+#[available_gas(999999999)]
+fn test_bit_length_most_significant_bit_one() {
+    assert(bit_length(4294967295_u32) == 32, 'bit length of 2^32-1 is 32');
+}