masking

[Special_K]

dose any one have a chart or a link on how to mask a random number to a number range?
like this



drive = randnum & %1111 'mask off number between 0-15



I need to mask one variable to numbers between 0 and 7 and one from 0 to 14.
should I use the max command?



randnum = drive MAX 7


any ideas?

Post Edited (Special_K) : 11/11/2006 4:51:44 AM GMT

[Chris Savage]

Hello,
·
·· The following thread has code for generating random numbers in a range.· The trick is in using the modulus operator.· Take care.

http://forums.parallax.com/showthread.php?p=522895

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Chris Savage
Parallax Tech Support

[Special_K]

i AM USING THIS CODE



drive = randnum // DDIR 'ddir = 7
DEBUG "drive",BIN drive,CR
DEBUG "drive TIME",BIN dTIME,CR
BRANCH drive, [FORward, rightturn1, FORward, backward, forward, leftturn1, halt, FORward ]
tdone:
RETURN


but I am getting numbers way out of range
drive can equal 100

[Mike Green]

BIN drive
This displays the value of drive as a binary number. "100" in binary is the value four which is a correct value for what you're trying to do.

[TechnoRobbo]

I addition to Mr. Green's advice let me point out that you have 8 BRANCH choices you'll never get to the eight one with your code:

·········· drive·=·randnum·//·DDIR······'ddir·=·7

Modulus is the remainder of a division therefore the remainder of a division by 7 is 0 to 6 inclusive.

Try setting DDIR to 8 your results will be 0 to 7 inclusive and thats what the ·"BRANCH" instructions looking for.

Of course your code uses the "Forward" label 4 times so it won't matter too much in this example, but if you reuse your code elsewhere or decide to trim down you BRANCH statement it will give you problems.
·

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Have Fun


TR

Post Edited (TechnoRobbo) : 11/15/2006 11:33:28 AM GMT

[Special_K]

thanks,
I found the BIN thing last night and changed it forgot to update.
I will change the ddir to equal 8.
The branch code has forward 4 times to stack the deck because I want the random motion to be more forward rather then in circles.