X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Frandom.lisp;h=373a3b2e5b3c203f15b06f27629aa79c5756c6a6;hb=4078d29d83e45a0b059ca5a71877ec36a4174a01;hp=2ff73367fe3061b288a307cdb65cbfb8d28ac2c6;hpb=85c34f4d1257df20fe1ab6f0d4d476bb3ec0bc63;p=sbcl.git

diff --git a/src/code/random.lisp b/src/code/random.lisp
index 2ff7336..373a3b2 100644
--- a/src/code/random.lisp
+++ b/src/code/random.lisp
@@ -9,9 +9,21 @@
 
 (in-package "SB!KERNEL")
 
-;;; our implementation of the RANDOM-STATE type specified by ANSI CL
+;;; the size of the chunks returned by RANDOM-CHUNK
+(def!constant random-chunk-length 32)
+
+;;; the amount that we overlap chunks by when building a large integer
+;;; to make up for the loss of randomness in the low bits
+(def!constant random-integer-overlap 3)
+
+;;; extra bits of randomness that we generate before taking the value MOD the
+;;; limit, to avoid loss of randomness near the limit
+(def!constant random-integer-extra-bits 10)
+
+;;; the largest fixnum we can compute from one chunk of bits
+(def!constant random-fixnum-max
+  (1- (ash 1 (- random-chunk-length random-integer-extra-bits))))
+
 (sb!xc:defstruct (random-state (:constructor %make-random-state)
-                               ;; Shallow copy would be wrong: we must
-                               ;; effectively COPY-SEQ the STATE slot.
-                               (:copier nil))
+                               (:copier nil)) ; since shallow copy is wrong
   (state (init-random-state) :type (simple-array (unsigned-byte 32) (627))))