How to keep a running total in assembly code? ARM cortex M3 (Keil software)

Question

Total beginner here. I'm trying to keep a running total of R5 but it keeps resetting back to the original value I had it set to. R3 is keeping up but R5 won't

This is the part of the problem I am working on.

Summation

lessThan
    CMP R3, R4
    ADD R5, R3, R3
    RSB R5, R5, #60
    ADDLE R3, R3, #1
    ADD R5, R5, #6
    ADD R5, R5, R4
    BLE lessThan

I am ending up with my R5 being (in decimal) 48 when it's actually supposed to be 780.

Answer 1

ADD R5, R3, R3 sets r5 = r3*2 , throwing away the old value of R5 inside every loop iteration.

Did you mean add r5, r5, r3 to do r5 += r3 ? Or did you need a scratch register?

IDK what you want your code to do, or why, but the my first paragraph is the answer to why R5 isn't accumulating a separate total.