Marc R Boehlen wrote:
>
> Folks
>
> I am new to this community and would like to ask if anyone has a routine
> for a 16C84 to generate random numbers?
>
> thanks,                            marc bohlen

This is a routine Dave Reinagel posted a while ago.


For a 16 bit pseudo-random number (2**16-1 states):

random          res     2;      reserve space for number
...
; on power-up, initialize the number to any non-zero value
        movlw   1;
        movwf   random+1;
...
; to get the next pseudo-random number
        clrf    temp1;          to make the next value
        movfw   random;         get high byte
        andlw   0xB4;           isolate bits for exclusive or
        movwf   temp2;
loop:   movfw   temp2;
        addwf   temp2,f;        shift temp and set Z when done
        btfsc   STATUS,C;       check if next bit is set
        incfsz  temp1,f;
        btfss   STATUS,Z;       check if temp2 is now zero
        goto    loop;
        rrf     temp1,f;        get parity of random ^ 0xB4 into C
        rlf     random+1,f;     now shift random number to the left
        rlf     random,f;
...

Now if you initialize the random number to the same seed everytime,
you will always get the same pattern of numbers out.  So you might
want to try using the value of a timer initially to seed the pseudo-
random number generator, but make sure it is not zero.

Enjoy,

Peter.
--
Peter Homann   email: peterh@adacel.com.au       Work : +61 3 9596-2991
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