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Help with Nybble variables


STGraves
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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?

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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.

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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

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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.

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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.

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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 ..
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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

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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
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