Ship Engines -

#engines -negative input
alias MemEngUpDown d0 #-101 +101
alias MemEngNS d1
alias MemEngWE d2
#output
alias EnginesDown d3
alias EnginesS d4
alias EnginesW d5

alias EngDown r1
alias EngS r2
alias EngW r3
alias ThrustMod r4

Start:
l ThrustMod db Setting #modifier from dial
mul ThrustMod ThrustMod -1 #to positive thrust

UpDown:
l EngDown MemEngUpDown Setting
brltz EngDown 3 #if negative, use it
s EnginesDown Setting 0 #zero\posit is zero
j NS
mul EngDown EngDown ThrustMod #mod
s EnginesDown Setting EngDown

NS:
l EngS MemEngNS Setting
brltz EngS 3 #if negative, use it
s EnginesS Setting 0 #zero\posit is zero
j WE
mul EngS EngS ThrustMod #modifier of thrust
s EnginesS Setting EngS

WE:
l EngW MemEngWE Setting
brltz EngW 3 #if negative, use it
s EnginesW Setting 0 #zero\posit is zero
j Tick
mul EngW EngW ThrustMod #modifier of thrust
s EnginesW Setting EngW

Tick:
yield
j Start