[UNTESTED] refactor how instructions are parsed

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

src/cpu/utility.hh

@@ -72,6 +72,20 @@ enum class ShiftType {
     ROR = 0b11
 };
 
+struct ShiftData {
+    ShiftType type;
+    bool immediate;
+    uint8_t operand;
+};
+
+struct Shift {
+    uint8_t rm;
+    ShiftData data;
+};
+
+uint32_t
+eval_shift(ShiftType shift_type, uint32_t value, uint8_t amount, bool& carry);
+
 // https://fmt.dev/dev/api.html#std-ostream-support
 std::ostream&
 operator<<(std::ostream& os, const ShiftType cond);