random: faster random-bits, make some things private.

[factor.git] / basis / random / random.factor

diff --git a/basis/random/random.factor b/basis/random/random.factor
index 25c7f718d3b0976f231904bc9244b325d76f3ca6..0c232611c84a42dbb33b4ea0de0695a4f981407b 100644 (file)
--- a/basis/random/random.factor
+++ b/basis/random/random.factor
@@ -14,11 +14,11 @@ SYMBOL: system-random-generator
 SYMBOL: secure-random-generator
 SYMBOL: random-generator
 
-GENERIC# seed-random 1 ( tuple seed -- tuple' )
-GENERIC: random-32* ( tuple -- r )
-GENERIC: random-bytes* ( n tuple -- byte-array )
+GENERIC# seed-random 1 ( obj seed -- obj )
+GENERIC: random-32* ( obj -- r )
+GENERIC: random-bytes* ( n obj -- byte-array )
 
-M: object random-bytes* ( n tuple -- byte-array )
+M: object random-bytes* ( n obj -- byte-array )
     [ integer>fixnum-strict [ <byte-array> ] keep ] dip
     [ over 4 >= ] [
         [ 4 - ] dip
@@ -27,7 +27,7 @@ M: object random-bytes* ( n tuple -- byte-array )
         random-32* c:int <ref> swap head 0 pick copy-unsafe
     ] if ;
 
-M: object random-32* ( tuple -- r )
+M: object random-32* ( obj -- r )
     4 swap random-bytes* c:uint deref ;
 
 ERROR: no-random-number-generator ;
@@ -47,35 +47,48 @@ M: f random-32* ( obj -- * ) no-random-number-generator ;
 
 <PRIVATE
 
-: #bits ( n -- bits )
+:: (random-bits) ( numbits obj -- r )
+    numbits 32 > [
+        obj random-32* numbits 32 - [ dup 32 > ] [
+            [ 32 shift obj random-32* + ] [ 32 - ] bi*
+        ] while [
+            [ shift ] keep obj random-32* swap bits +
+        ] unless-zero
+    ] [
+        obj random-32* numbits bits
+    ] if ; inline
+
+PRIVATE>
+
+: random-bits ( numbits -- r )
+    random-generator get (random-bits) ;
+
+: random-bits* ( numbits -- r )
+    1 - [ random-bits ] keep set-bit ;
+
+<PRIVATE
+
+: next-power-of-2-bits ( n -- numbits )
     dup 2 <= [ drop 1 ] [ 1 - log2 1 + ] if ; inline
 
-:: (random-bits) ( n bits obj -- n' )
-    obj random-32* 32 bits 32 - [ dup 0 > ] [
+:: ((random-integer)) ( n obj -- r )
+    obj random-32* 32 n next-power-of-2-bits 32 - [ dup 0 > ] [
         [ 32 shift obj random-32* + ] [ 32 + ] [ 32 - ] tri*
     ] while drop [ n * ] [ neg shift ] bi* ; inline
 
-: ((random-integer)) ( n obj -- n' )
-    [ dup #bits ] dip (random-bits) ; inline
-
-GENERIC# (random-integer) 1 ( n obj -- n )
-M: fixnum (random-integer) ( n obj -- n' ) ((random-integer)) ;
-M: bignum (random-integer) ( n obj -- n' ) ((random-integer)) ;
+GENERIC# (random-integer) 1 ( n obj -- r )
+M: fixnum (random-integer) ( n obj -- r ) ((random-integer)) ;
+M: bignum (random-integer) ( n obj -- r ) ((random-integer)) ;
 
-: random-integer ( n -- n' )
+: random-integer ( n -- r )
     random-generator get (random-integer) ;
 
 PRIVATE>
 
-: random-bits ( numbits -- r )
-    [ 2^ ] keep random-generator get (random-bits) ;
-
-: random-bits* ( numbits -- n )
-    1 - [ random-bits ] keep set-bit ;
-
 GENERIC: random ( obj -- elt )
 
-M: integer random [ f ] [ random-integer ] if-zero ;
+M: integer random
+    [ f ] [ random-integer ] if-zero ;
 
 M: sequence random
     [ f ] [
@@ -122,7 +135,7 @@ ERROR: too-many-samples seq n ;
     [ length random-integer ] keep
     [ nth ] 2keep remove-nth! drop ;
 
-: with-random ( tuple quot -- )
+: with-random ( obj quot -- )
     random-generator swap with-variable ; inline
 
 : with-system-random ( quot -- )
@@ -162,12 +175,16 @@ PRIVATE>
 : random-integers ( length n -- sequence )
     random-generator get '[ _ _ (random-integer) ] replicate ;
 
+<PRIVATE
+
 : (cos-random-float) ( -- n )
     0. 2pi uniform-random-float cos ;
 
 : (log-sqrt-random-float) ( -- n )
     random-unit log -2. * sqrt ;
 
+PRIVATE>
+
 : normal-random-float ( mean sigma -- n )
     (cos-random-float) (log-sqrt-random-float) * * + ;
 
@@ -186,6 +203,8 @@ PRIVATE>
 : pareto-random-float ( k alpha -- n )
     [ random-unit ] dip recip ^ /f ;
 
+<PRIVATE
+
 :: (gamma-random-float>1) ( alpha beta -- n )
     ! Uses R.C.H. Cheng, "The generation of Gamma
     ! variables with non-integral shape parameters",
@@ -237,6 +256,8 @@ PRIVATE>
         ] if x!
     ] do while x beta * ;
 
+PRIVATE>
+
 : gamma-random-float ( alpha beta -- n )
     {
         { [ over 1 > ] [ (gamma-random-float>1) ] }
@@ -275,6 +296,8 @@ PRIVATE>
         rnd (random-unit) 0.5 > [ + ] [ - ] if
     ] if ;
 
+<PRIVATE
+
 :: (triangular-random-float) ( low high mode -- n )
     mode low - high low - / :> c!
     random-unit :> u!
@@ -282,6 +305,8 @@ PRIVATE>
     u c > [ 1. u - u! 1. c - c! swap ] when
     [ - u c * sqrt * ] keep + ;
 
+PRIVATE>
+
 : triangular-random-float ( low high -- n )
     2dup + 2 /f (triangular-random-float) ;