Need Snippets for Random Numbers

[sokoban]

Hello,

I found quite all I need to make some small and easy games on the forum and also with the Soeren examples
But there is only one thing that I absolutely don't understand: how to generate random numbers
I have read that there is a Videopac routine that is not compatible with Videopac+
But I have also read it is possible to generate random numbers without this routine and this is why I post my message today
Basically, how is it possible to generate a random number between 0 and X (where X is a 8 bits integer)

Help needed, Thanks for all,
Sokoban

[LD]

This is a neat little random code I've adapted from 6502 assembly :

Code:

;--------------------------------------
RandomNumber                          ;subroutine
mov R0,#RandomVar
mov a,@R0
clr c
rrc a
jc Neor
xrl a,#0B4h
Neor
mov @R0,a
ret

Where RandomVar is an int. RAM. This generates 0-255 possible numbers and never repeats. Call this code once every frame.

To limit the result is more difficult, you can use ANL to limit the range of A ex.:

anl a,#003h ;limit A to 0-3
anl a,#007h ;limit A to 0-7
anl a,#00Fh ;limit A to 0-15
anl a,#01Fh ; limit A to 0-31
anl a,#03Fh ; limit A to 0-63
anl a,#07Fh ; limit A to 0-127

load the random var to A and use ANL.

 mov a,@R0 ;where R0 is the random var (int RAM)
 anl a,#00Fh

 now A could be 0 up to 15

[sokoban]

Thank you very much LD!!
I will try this in a few days.

[sokoban]

tested... and it works!!
thanks again!
now i have no more excuses not to make a game ^^