Help with Nybble variables

[STGraves]

I read through the RT's website and found the nybble variables, thought they were very interesting and could be very helpful so I decided to try them out in my game, I thought I had understood how to use them and how do they worked but I couldn't figure out how to use them in a if... then statement that has multiple variables with different values on it, how can I implement them in such statement?

[+Random Terrain]

If you are a beginner, it's best to avoid nybble variables.

At one time batari was thinking about adding the ability to easily create nybble variables without the user needing to jump through a dozen flaming hoops. I don't know what the plan was. Maybe something like the following?
_

   dim _Flying_Monkey = a_lo
   dim _Smelly_Socks = a_hi

_
or
_

   dim _Flying_Monkey = a(lo)
   dim _Smelly_Socks = a(hi)

_

After DIMing, _Flying_Monkey and _Smelly_Socks would act like normal variables, but they would roll over from 15 to 0 and 0 to 15 in the other direction. bB would take care of the calculations and the user could use nybble variables without any worries. There are a lot of times when a full variable isn't needed, and a simple way to use nybble variables would be very helpful.

 

If someone starts working on batari Basic again, I hope nybble variables will be near the top of the to-do list.

[STGraves]

I'm not that much of a beginner any more, the reason why I want to use nybble's is because the default variables from bB aren't enough for what I want to do in my game, it uses more than 26 variables, because of the music and other stuff. If I send you a copy of my game without the nybble's and also the independet bas file with the music, could you help me to get it to work during the game? Yes the variables are for using music in the game. Thanks

[+Random Terrain]

I'm not that much of a beginner any more, the reason why I want to use nybble's is because the default variables from bB aren't enough for what I want to do in my game, it uses more than 26 variables, because of the music and other stuff. If I send you a copy of my game without the nybble's and also the independet bas file with the music, could you help me to get it to work during the game? Yes the variables are for using music in the game. Thanks

 

Nope. I stopped trying to use nybble variables in 2010:

 

atariage.com/forums/blog/120/entry-6912-scrolling-game-is-rolling-along-part-4/

 

atariage.com/forums/blog/120/entry-6915-scrolling-game-is-rolling-along-part-5/

 

 

You can get more variables by using Superchip RAM. You get 48 extra normal variables (var0 through var47) and some special weird ones that have to be used VERY carefully.

[STGraves]

No, I meant helping trying to get it to work WITHOUT THE NYBBLE VARIABLES.

[+Random Terrain]

No, I meant helping trying to get it to work WITHOUT THE NYBBLE VARIABLES.

 

Like I said, just switch to Superchip RAM.

[STGraves]

Ok, I've just read through your site in the superchip ram but I didn't understand how to use it and how it works.

[+Random Terrain]

Ok, I've just read through your site in the superchip ram but I didn't understand how to use it and how it works.

 

It takes most people on this planet longer than 19 minutes to study something and to run little experiments.

 

I'll see if I can add an example program to that section within the next week or two, but until then, I'm sure that you can find Superchip code examples that people have posted in this forum over the years.

[STGraves]

Hahahaha, ok thanks for the help RT

[bogax]

I read through the RT's website and found the nybble variables, thought they were very interesting and could be very helpful so I decided to try them out in my game, I thought I had understood how to use them and how do they worked but I couldn't figure out how to use them in a if... then statement that has multiple variables with different values on it, how can I implement them in such statement?

 

How about an example?

 

 

Probably the simplest thing would be to use temp variables

 

 

temp1 = nybble
 
if temp1 then ..

[STGraves]

 

 

How about an example?

 

 

Probably the simplest thing would be to use temp variables

 

temp1 = nybble
 
if temp1 then ..

Thanks,I did understood it but what I don't understand is how to make sure to not to repeat any temp value throughout the game, I mean how do I know they're not repeating,on the game there are some variables that I have to increment, and other that have to be decremented

[bogax]

I think you will have to give an example

I don't understand what you are worried about repeating

what sort of things do you want to do with nybbles?

(some code would be nice)

I think RT had bunch of this stuff but here you go

 rem  to add something to the hi nybble of a

 rem  shift it four places to the left by multiplying

 rem  it by 16

 

 rem  increment the high nybble of a

 rem  ie add 1 to the hi nybble

 a = a + 16

 

 rem  decrement the high nybble of a

 a =  a - 16

 

 rem  add the lo nybble of b to the hi nybble of a

 a = b * 16 + a

 

 rem  if you can't do the shifting first it's better

 rem  to use a temp variable if you can or else bB

 rem  starts messing with the stack to save intermediates

 

 rem  subtract the lo nybble of b from the hi nybble of a

 temp1 = b * 16

 a = a - temp1

 

 rem  use an XOR swap to set the lo nybble of a 

 rem  to the lo nybble of something else

 rem  with out effecting the hi nybble of a

 rem  the something else being temp1 here 

 a = ((temp1 ^ a) & %11110000) ^ temp1

 

 rem  and use the parenthesis or else bB will mess with

 rem  stack for intermediates

 

 

 rem  do what ever in a temp variable then

 rem  swap it back in to a

 

 rem  increment the lo nybble of a 

 temp1 = a + 1

 a = (temp1 ^ a) & %11110000 ^ temp1 

 

 rem  decrement the lo nybble of a 

 temp1 = a - 1

 a = (temp1 ^ a) & %11110000 ^ temp1 

 

 rem  add lo nybble of b to lo nybble of a 

 temp1 = a + b

 a = (temp1 ^ a) & %11110000 ^ temp1 

 

 rem  to set the low nybble of a to the lo nybble of b

 a = (b ^ a) & %11110000 ^ b 

 

 

 rem  to set the hi nybble of a to the hi nybble 

 rem  of something else (temp1 in this case)

 a = (temp1 ^ a) & %00001111 ^ temp1

 

 

 rem  to set the hi nybble of a to the lo nybble

 rem  of something else shift the something else 4 bits

 rem  mask out the hi nybble of a and OR in the (shifted)

 rem  lo nybble

 temp1 = b * 16

 a = (a & %00001111) | temp1 

you can put this stuff in macros

and you don't have to use nybbles if could eg be the hi 5 bits

and the lo 3 bits but the constants would change

eg multiply by 8 for the 5 hi bits

mask with %11111000 for the 5 hi bits

or %00000111 for the lo 3 bits

[Papa]

All this talk about nybbles and chips is making me hungry!!

 

 

 

...and then killer killed nybbles!

Edited May 30, 2015 by Papa

[STGraves]

bogax, do you want me to post my code for you to understand it?