22 lines
537 B
Factor
22 lines
537 B
Factor
|
! Copyright (C) 2003, 2005 Slava Pestov.
|
||
|
|
! See http://factor.sf.net/license.txt for BSD license.
|
||
|
|
IN: math USING: kernel ;
|
||
|
|
|
||
|
|
: power-of-2? ( n -- ? ) dup dup neg bitand = ;
|
||
|
|
|
||
|
|
: (random-int-0) ( n bits val -- n )
|
||
|
|
3dup - + 1 < [
|
||
|
|
2drop (random-int) 2dup swap mod (random-int-0)
|
||
|
|
] [
|
||
|
|
2nip
|
||
|
|
] ifte ;
|
||
|
|
|
||
|
|
: random-int-0 ( max -- n )
|
||
|
|
1 + dup power-of-2? [
|
||
|
|
(random-int) * -31 shift
|
||
|
|
] [
|
||
|
|
(random-int) 2dup swap mod (random-int-0)
|
||
|
|
] ifte ;
|
||
|
|
|
||
|
|
: random-int ( min max -- n ) dupd swap - random-int-0 + ;
|