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randomgforth

Gforth random generator has no seed

The following program in gforth prints out 10 random numbers between 0 and 2:

require random.fs
: main 10 0 do i cr . 3 random . loop ;
main

The problem is, that after each start, the numbers are the same. That means no time(0) seed was used. How can i get random numbers which are different on each start?

Solution

  • In the GPL-licensed source file random.fs:

    Variable seed
$10450405 Constant generator
: rnd  ( -- n )  seed @ generator um* drop 1+ dup seed ! ;
: random ( n -- 0..n-1 )  rnd um* nip ;

    To grab a random number you can seed the variable seed with a line, perhaps like this:

    utime drop seed !

    However I'm no cryptographer, but I'm under the impression seeding with the current time isn't cryptographically secure. I wouldn't use this in any production code.