Tutorial 4 in 112 cycles?

[DupLawyer]

I've been going back and looking at early code to optimize but I can't see how to do "trash the news tutorial 4" (the countdown one" in so few lines.

I'd really like to understand how this was done as it will likely transfer to other solutions...

my code is below (400 cycles)

I can't see how to reduce two instructions out of the loop!!
If I use "SUBI X 1 F" or "F 1 F" I need to SEEK to test...
I'm missing some what of not needing to test perhaps...

LINK 800
GRAB 200
COPY F X
WIPE

LINK 800
MAKE 
COPY X F

MARK LOOP
  SUBI X 1 X
  COPY X F
  TEST X = 0
  FJMP LOOP

[Juling]

By using the T register you can omit the test since FJMP will trigger on T = 0.

Also, by using more than one exa...

[jokeserver]

The T register trick will get you down to 300ish, because you'll still have a loop of size 3 for the 99 case. 112 cycles means you have to reduce the amortized cost per item... once I realized this and figured out the right number, I got it down to 147.

And remember, that number's the max among all the test cases.

[DupLawyer]

ahhh, I never thought of that usage of T, very clever