458 lines
11 KiB
Plaintext
458 lines
11 KiB
Plaintext
;The Scheme code in this file provides some compatibility with scripts that
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;were originally written for use with the older SIOD based Script-Fu plug-in
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;of PIKA.
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;
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;All items defined in this file except for the random number routines are
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;deprecated. Existing scripts should be updated to avoid the use of the
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;compatibility functions and define statements which follow the random number
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;generator routines.
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;
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;The items marked as deprecated at the end of this file may be removed
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;at some later date.
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;The random number generator routines below have been slightly reformatted.
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;A couple of define blocks which are not needed have been commented out.
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;It has also been extended to enable it to generate numbers with exactly 31
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;bits or more.
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;The original file was called rand2.scm and can be found in:
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;http://www-2.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/scheme/code/math/random/
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; Minimal Standard Random Number Generator
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; Park & Miller, CACM 31(10), Oct 1988, 32 bit integer version.
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; better constants, as proposed by Park.
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; By Ozan Yigit
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;(define *seed* 1)
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(define (srand seed)
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(set! *seed* seed)
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*seed*
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)
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(define (msrg-rand)
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(let (
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(A 48271)
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(M 2147483647)
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(Q 44488)
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(R 3399)
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)
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(let* (
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(hi (quotient *seed* Q))
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(lo (modulo *seed* Q))
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(test (- (* A lo) (* R hi)))
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)
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(if (> test 0)
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(set! *seed* test)
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(set! *seed* (+ test M))
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)
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)
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)
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*seed*
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)
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; poker test
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; seed 1
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; cards 0-9 inclusive (random 10)
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; five cards per hand
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; 10000 hands
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;
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; Poker Hand Example Probability Calculated
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; 5 of a kind (aaaaa) 0.0001 0
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; 4 of a kind (aaaab) 0.0045 0.0053
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; Full house (aaabb) 0.009 0.0093
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; 3 of a kind (aaabc) 0.072 0.0682
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; two pairs (aabbc) 0.108 0.1104
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; Pair (aabcd) 0.504 0.501
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; Bust (abcde) 0.3024 0.3058
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(define (random n)
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(define (internal-random n)
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(let* (
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(n (inexact->exact (truncate n)))
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(M 2147483647)
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(slop (modulo M (abs n)))
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)
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(let loop ((r (msrg-rand)))
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(if (>= r slop)
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(modulo r n)
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(loop (msrg-rand))
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)
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)
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)
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)
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; Negative numbers have a bigger range in twos complement platforms
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; (nearly all platforms out there) than positive ones, so we deal with
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; the numbers in negative form.
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(if (> n 0)
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(+ n (random (- n)))
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(if (>= n -2147483647)
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(internal-random n)
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; 31-or-more-bits number requested - needs multiple extractions
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; because we don't generate enough random bits.
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(if (>= n -1152921504606846975)
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; Up to 2^60-1, two extractions are enough
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(let ((q (- (quotient (+ n 1) 1073741824) 1))) ; q=floor(n/2^30)
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(let loop ()
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(let ((big (+ (* (internal-random q) 1073741824)
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(internal-random -1073741824)
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)
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))
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(if (> big n)
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big
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(loop)
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)
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)
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)
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)
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; From 2^60 up, we do three extractions.
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; The code is better understood if seen as generating three
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; digits in base 2^30. q is the maximum value the first digit
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; can take. The other digits can take the full range.
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;
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; The strategy is to generate a random number digit by digit.
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; Here's an example in base 10. Say the input n is 348
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; (thus requesting a number between 0 and 347). Then the algorithm
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; first calls (internal-random 4) to get a digit between 0 and 3,
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; then (internal-random 10) twice to get two more digits between
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; 0 and 9. Say the result is 366: since it is greater than 347,
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; it's discarded and the process restarted. When the result is
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; <= 347, that's the returned value. The probability of it being
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; greater than the max is always strictly less than 1/2.
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;
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; This is the same idea but in base 2^30 (1073741824). The
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; first digit's weight is (2^30)^2 = 1152921504606846976,
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; similarly to how in our base 10 example, the first digit's
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; weight is 10^2 = 100. In the base 10 example we first divide
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; the target number 348 by 100, taking the ceiling, to get 4.
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; Here we divide by (2^30)^2 instead, taking the ceiling too.
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;
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; The math is a bit obscured by the fact that we generate
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; the digits as negative, so that the result is negative as
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; well, but it's really the same thing. Changing the sign of
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; every digit just changes the sign of the result.
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;
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; This method works for n up to (2^30)^2*(2^31-1) which is
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; 2475880077417839045191401472 (slightly under 91 bits). That
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; covers the 64-bit range comfortably, and some more. If larger
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; numbers are needed, they'll have to be composed with a
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; user-defined procedure.
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(if (>= n -2475880077417839045191401472)
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(let ((q (- (quotient (+ n 1) 1152921504606846976) 1))) ; q=floor(n/2^60)
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(let loop ()
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(let ((big (+ (* (internal-random q) 1152921504606846976)
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(* (internal-random -1073741824) 1073741824)
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(internal-random -1073741824)
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)
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))
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(if (> big n)
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big
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(loop)
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)
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)
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)
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)
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(error "requested (random n) range too large")
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)
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)
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)
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)
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)
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;(define (rngtest)
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; (display "implementation ")
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; (srand 1)
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; (do
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; ( (n 0 (+ n 1)) )
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; ( (>= n 10000) )
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; (msrg-rand)
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; )
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; (if (= *seed* 399268537)
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; (display "looks correct.")
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; (begin
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; (display "failed.")
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; (newline)
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; (display " current seed ") (display *seed*)
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; (newline)
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; (display " correct seed 399268537")
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; )
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; )
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; (newline)
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;)
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;This macro defines a while loop which is needed by some older scripts.
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;This is here since it is not defined in R5RS and could be handy to have.
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;This while macro was found at:
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;http://www.aracnet.com/~briand/scheme_eval.html
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(define-macro (while test . body)
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`(let loop ()
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(cond
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(,test
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,@body
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(loop)
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)
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)
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)
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)
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;The following define block(s) require the tsx extension to be loaded
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(define (realtime)
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(car (gettimeofday))
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)
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;Items below this line are for compatibility with Script-Fu but
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;may be useful enough to keep around
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(define (delq item lis)
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(let ((l '()))
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(unless (null? lis)
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(while (pair? lis)
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(if (<> item (car lis))
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(set! l (append l (list (car lis))))
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)
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(set! lis (cdr lis))
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)
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)
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l
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)
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)
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(define (make-list count fill)
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(vector->list (make-vector count fill))
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)
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(define (strbreakup str sep)
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(let* (
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(seplen (string-length sep))
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(start 0)
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(end (string-length str))
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(i start)
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(l '())
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)
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(if (= seplen 0)
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(set! l (list str))
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(begin
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(while (<= i (- end seplen))
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(if (substring-equal? sep str i (+ i seplen))
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(begin
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(if (= start 0)
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(set! l (list (substring str start i)))
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(set! l (append l (list (substring str start i))))
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)
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(set! start (+ i seplen))
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(set! i (+ i seplen -1))
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)
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)
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(set! i (+ i 1))
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)
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(set! l (append l (list (substring str start end))))
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)
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)
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l
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)
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)
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(define (string-downcase str)
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(list->string (map char-downcase (string->list str)))
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)
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(define (string-trim str)
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(string-trim-right (string-trim-left str))
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)
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(define (string-trim-left str)
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(let (
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(strlen (string-length str))
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(i 0)
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)
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(while (and (< i strlen)
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(char-whitespace? (string-ref str i))
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)
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(set! i (+ i 1))
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)
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(substring str i (string-length str))
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)
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)
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(define (string-trim-right str)
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(let ((i (- (string-length str) 1)))
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(while (and (>= i 0)
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(char-whitespace? (string-ref str i))
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)
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(set! i (- i 1))
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)
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(substring str 0 (+ i 1))
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)
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)
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(define (string-upcase str)
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(list->string (map char-upcase (string->list str)))
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)
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(define (substring-equal? str str2 start end)
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(string=? str (substring str2 start end))
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)
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(define (unbreakupstr stringlist sep)
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(let ((str (car stringlist)))
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(set! stringlist (cdr stringlist))
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(while (not (null? stringlist))
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(set! str (string-append str sep (car stringlist)))
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(set! stringlist (cdr stringlist))
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)
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str
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)
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)
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;Items below this line are deprecated and should not be used in new scripts.
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(define aset vector-set!)
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(define aref vector-ref)
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(define fopen open-input-file)
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(define mapcar map)
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(define nil '())
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(define nreverse reverse)
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(define pow expt)
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(define prin1 write)
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(define (print obj . port)
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(apply write obj port)
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(newline)
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)
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(define strcat string-append)
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(define string-lessp string<?)
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(define symbol-bound? defined?)
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(define the-environment current-environment)
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(define *pi*
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(* 4 (atan 1.0))
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)
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(define (butlast x)
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(if (= (length x) 1)
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'()
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(reverse (cdr (reverse x)))
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)
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)
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(define (cons-array count type)
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(case type
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((long) (make-vector count 0))
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((short) (make-vector count 0))
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((byte) (make-vector count 0))
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((double) (make-vector count 0.0))
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((string) (vector->list (make-vector count "")))
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(else type)
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)
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)
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(define (fmod a b)
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(- a (* (truncate (/ a b)) b))
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)
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(define (fread arg1 file)
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(define (fread-get-chars count file)
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(let (
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(str "")
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(c 0)
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)
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(while (> count 0)
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(set! count (- count 1))
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(set! c (read-char file))
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(if (eof-object? c)
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(set! count 0)
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(set! str (string-append str (make-string 1 c)))
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)
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)
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(if (eof-object? c)
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()
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str
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)
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)
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)
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(if (number? arg1)
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(begin
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(set! arg1 (inexact->exact (truncate arg1)))
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(fread-get-chars arg1 file)
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)
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(begin
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(set! arg1 (fread-get-chars (string-length arg1) file))
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(string-length arg1)
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)
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)
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)
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(define (last x)
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(cons (car (reverse x)) '())
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)
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(define (nth k list)
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(list-ref list k)
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)
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(define (prog1 form1 . form2)
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(let ((a form1))
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(if (not (null? form2))
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form2
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)
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a
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)
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)
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(define (rand . modulus)
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(if (null? modulus)
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(msrg-rand)
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(apply random modulus)
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)
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)
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(define (strcmp str1 str2)
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(if (string<? str1 str2)
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-1
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(if (string>? str1 str2)
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1
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0
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)
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)
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)
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(define (trunc n)
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(inexact->exact (truncate n))
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)
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(define verbose
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(lambda n
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(if (or (null? n) (not (number? (car n))))
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0
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(car n)
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)
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)
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)
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