LMC - Multiplier where second input is greater than or equal to zero

INP
STA base
INP
SUB one
STA mValue
BRP mainloop

LDA mValue
ADD one
BRZ zeroMulti

mainloop LDA total
ADD base
STA total
LDA mValue
SUB one
STA mValue
BRP mainloop

LDA total
OUT
HLT

zeroMulti LDA zero
OUT
HLT

base DAT
mValue DAT
total DAT
one DAT 1
zero DAT 0