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isaac-32.lisp
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;;;; -*- Mode: LISP; Syntax: COMMON-LISP; Package: CL-ISAAC; Base: 10 -*- file: isaac-32.lisp
;; Copyright (c) 2008 Doug Hoyte, HCSW
;; Copyright (c) 2014--2022, "the Phoeron" Colin J.E. Lupton
;; BSD license: you can do anything you want with it (but no warranty).
(in-package #:cl-isaac)
(defstruct isaac-ctx
(randcnt 0 :type (unsigned-byte 32))
(randrsl (make-array 256 :element-type '(unsigned-byte 32) :initial-element 0)
:type (simple-array (unsigned-byte 32) (256)))
(randmem (make-array 256 :element-type '(unsigned-byte 32) :initial-element 0)
:type (simple-array (unsigned-byte 32) (256)))
(a 0 :type (unsigned-byte 32))
(b 0 :type (unsigned-byte 32))
(c 0 :type (unsigned-byte 32)))
(defun generate-next-isaac-block (ctx)
;(declare (optimize (speed 3) (safety 0)))
(incf (isaac-ctx-c ctx))
(incf (isaac-ctx-b ctx) (isaac-ctx-c ctx))
(loop for i from 0 below 256 do
(setf (isaac-ctx-a ctx)
(logxor (isaac-ctx-a ctx)
(the (unsigned-byte 32)
(logand #xFFFFFFFF
(ash (isaac-ctx-a ctx)
(ecase (logand i 3)
((0) 13)
((1) -6)
((2) 2)
((3) -16)))))))
(setf (isaac-ctx-a ctx)
(logand #xFFFFFFFF
(+ (isaac-ctx-a ctx)
(aref (isaac-ctx-randmem ctx) (logand (+ i 128) #xFF)))))
(let* ((x (aref (isaac-ctx-randmem ctx) i))
(y (logand #xFFFFFFFF
(+ (aref (isaac-ctx-randmem ctx) (logand (ash x -2) #xFF))
(isaac-ctx-a ctx)
(isaac-ctx-b ctx)))))
(setf (aref (isaac-ctx-randmem ctx) i) y)
(setf (isaac-ctx-b ctx)
(logand #xFFFFFFFF
(+ (aref (isaac-ctx-randmem ctx) (logand (ash y -10) #xFF)) x)))
(setf (aref (isaac-ctx-randrsl ctx) i) (isaac-ctx-b ctx)))))
(defun rand32 (ctx)
(let ((c (isaac-ctx-randcnt ctx)))
;(declare (optimize (speed 3) (safety 0)))
(decf (isaac-ctx-randcnt ctx))
(if (zerop c)
(progn
(generate-next-isaac-block ctx)
(setf (isaac-ctx-randcnt ctx) 255)
(aref (isaac-ctx-randrsl ctx) 255))
(aref (isaac-ctx-randrsl ctx) (isaac-ctx-randcnt ctx)))))
(defun rand-bits (ctx n)
(let ((v 0))
(loop while (> n 0) do
(setq v (logior (ash v (min n 32))
(logand (1- (ash 1 (min n 32)))
(rand32 ctx))))
(decf n (min n 32)))
v))
(defmacro incf-wrap32 (a b)
`(setf ,a (logand #xFFFFFFFF (+ ,a ,b))))
(defmacro mix (a b c d e f g h)
`(progn
(setf ,a (logxor ,a (logand #xFFFFFFFF (ash ,b 11)))) (incf-wrap32 ,d ,a) (incf-wrap32 ,b ,c)
(setf ,b (logxor ,b (logand #xFFFFFFFF (ash ,c -2)))) (incf-wrap32 ,e ,b) (incf-wrap32 ,c ,d)
(setf ,c (logxor ,c (logand #xFFFFFFFF (ash ,d 8)))) (incf-wrap32 ,f ,c) (incf-wrap32 ,d ,e)
(setf ,d (logxor ,d (logand #xFFFFFFFF (ash ,e -16)))) (incf-wrap32 ,g ,d) (incf-wrap32 ,e ,f)
(setf ,e (logxor ,e (logand #xFFFFFFFF (ash ,f 10)))) (incf-wrap32 ,h ,e) (incf-wrap32 ,f ,g)
(setf ,f (logxor ,f (logand #xFFFFFFFF (ash ,g -4)))) (incf-wrap32 ,a ,f) (incf-wrap32 ,g ,h)
(setf ,g (logxor ,g (logand #xFFFFFFFF (ash ,h 8)))) (incf-wrap32 ,b ,g) (incf-wrap32 ,h ,a)
(setf ,h (logxor ,h (logand #xFFFFFFFF (ash ,a -9)))) (incf-wrap32 ,c ,h) (incf-wrap32 ,a ,b)))
(defun scramble (ctx)
(let (a b c d e f g h)
(setf a #x9e3779b9 b a c a d a e a f a g a h a) ; golden ratio
(loop for i from 0 below 4 do
(mix a b c d e f g h))
;; Pass #1
(loop for i from 0 below 256 by 8 do
(incf-wrap32 a (aref (isaac-ctx-randrsl ctx) (+ i 0)))
(incf-wrap32 b (aref (isaac-ctx-randrsl ctx) (+ i 1)))
(incf-wrap32 c (aref (isaac-ctx-randrsl ctx) (+ i 2)))
(incf-wrap32 d (aref (isaac-ctx-randrsl ctx) (+ i 3)))
(incf-wrap32 e (aref (isaac-ctx-randrsl ctx) (+ i 4)))
(incf-wrap32 f (aref (isaac-ctx-randrsl ctx) (+ i 5)))
(incf-wrap32 g (aref (isaac-ctx-randrsl ctx) (+ i 6)))
(incf-wrap32 h (aref (isaac-ctx-randrsl ctx) (+ i 7)))
(mix a b c d e f g h)
(setf (aref (isaac-ctx-randmem ctx) (+ i 0)) a)
(setf (aref (isaac-ctx-randmem ctx) (+ i 1)) b)
(setf (aref (isaac-ctx-randmem ctx) (+ i 2)) c)
(setf (aref (isaac-ctx-randmem ctx) (+ i 3)) d)
(setf (aref (isaac-ctx-randmem ctx) (+ i 4)) e)
(setf (aref (isaac-ctx-randmem ctx) (+ i 5)) f)
(setf (aref (isaac-ctx-randmem ctx) (+ i 6)) g)
(setf (aref (isaac-ctx-randmem ctx) (+ i 7)) h))
;; Pass #2
(loop for i from 0 below 256 by 8 do
(incf-wrap32 a (aref (isaac-ctx-randmem ctx) (+ i 0)))
(incf-wrap32 b (aref (isaac-ctx-randmem ctx) (+ i 1)))
(incf-wrap32 c (aref (isaac-ctx-randmem ctx) (+ i 2)))
(incf-wrap32 d (aref (isaac-ctx-randmem ctx) (+ i 3)))
(incf-wrap32 e (aref (isaac-ctx-randmem ctx) (+ i 4)))
(incf-wrap32 f (aref (isaac-ctx-randmem ctx) (+ i 5)))
(incf-wrap32 g (aref (isaac-ctx-randmem ctx) (+ i 6)))
(incf-wrap32 h (aref (isaac-ctx-randmem ctx) (+ i 7)))
(mix a b c d e f g h)
(setf (aref (isaac-ctx-randmem ctx) (+ i 0)) a)
(setf (aref (isaac-ctx-randmem ctx) (+ i 1)) b)
(setf (aref (isaac-ctx-randmem ctx) (+ i 2)) c)
(setf (aref (isaac-ctx-randmem ctx) (+ i 3)) d)
(setf (aref (isaac-ctx-randmem ctx) (+ i 4)) e)
(setf (aref (isaac-ctx-randmem ctx) (+ i 5)) f)
(setf (aref (isaac-ctx-randmem ctx) (+ i 6)) g)
(setf (aref (isaac-ctx-randmem ctx) (+ i 7)) h))
(generate-next-isaac-block ctx)
(setf (isaac-ctx-randcnt ctx) 256)
ctx))
;; EOF