I need to do a multiplication in the keil and the following mistake goes out for me. It does not leave me to use MLU and MUL. Why?
error: A1477W: This register combination results in UNPREDICTABLE behaviour
No, he actually specifically said that he "needs" (sic) to convert that particular piece of 'C' source into assembler - which is almost certainly not a real "need" (other than to satisfy a school assignment).
If he really "only wants to write a little assembly", then there would be far better places to start; eg, http://www.keil.com/books/armbooks.asp