steve
/
factor
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

random: performance improvements to random-integer and random-bits.

db4
John Benediktsson 2013-02-27 14:05:46 -08:00
parent 482096e1df
commit 8a5411cfc1
1 changed files with 8 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
basis/random/random.factor
View File

@ -46,21 +46,24 @@ TYPED: random-bytes ( n: fixnum -- byte-array: byte-array )
<PRIVATE
:: ((random-integer)) ( bits obj -- n required-bits )
: #bits ( n -- bits )
dup 2 <= [ drop 1 ] [ 1 - log2 1 + ] if ; inline
:: (random-bits) ( n bits obj -- n' )
obj random-32* 32 bits 32 - [ dup 0 > ] [
[ 32 shift obj random-32* + ] [ 32 + ] [ 32 - ] tri*
] while drop ;
] while drop [ n * ] [ 2^ /i ] bi* ; inline
: (random-integer) ( n obj -- n' )
[ dup next-power-of-2 log2 ] dip ((random-integer))
[ * ] [ 2^ /i ] bi* ;
[ dup #bits ] dip (random-bits) ;
: random-integer ( n -- n' )
random-generator get (random-integer) ;
PRIVATE>
: random-bits ( numbits -- r ) 2^ random-integer ;
: random-bits ( numbits -- r )
[ 2^ ] keep random-generator get (random-bits) ;
: random-bits* ( numbits -- n )
1 - [ random-bits ] keep set-bit ;