Project: clean up old code

In the lab there is a chip somebody wrote months ago. It works, but nobody dares to touch it. On top of that the lab is being rebuilt, and devices should be addressed by name instead of pins in future. Today you rebuild it – and the most important part is that afterwards it does exactly the same.

The old code#

start:
yield
l r0 d0 Temperature
slt r1 r0 291.15
s d1 On r1
sgt r2 r0 297.15
s d2 On r2
sub r3 r0 273.15
s d3 Setting r3
j 1

What it does: below 18 °C the heater runs, above 24 °C the cooler, and the display shows the temperature in °C.

The new devices#

The device names stay German – they are names in the game.

How to go about it#

1. Add a header and sections.
2. One define per device type with HASH("prefab") and a comment.
3. The three numbers into defines: 291.15 K (18 °C), 297.15 K (24 °C), 273.15 as CELSIUSOFFSET.
4. Every register gets an alias.
5. l and s with pins become lbn and sbn with HASH("name"), batch mode Average.
6. j 1 becomes j start.

Run the tests after every step. A rebuild that stays green along the way is a safe rebuild.

Milestones#

1. Cold: heater on.
2. Warm: cooler on.
3. The display shows °C.
4. In the band between 18 and 24 °C: both off.