/usr/share/scsh-0.6/misc/ilength.scm is in scsh-common-0.6 0.6.7-8.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | ; Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees. See file COPYING.
; Integer-length, a la Common Lisp, written in portable Scheme.
(define-syntax cons-stream
(syntax-rules ()
((cons-stream head tail)
(cons head (delay tail)))))
(define head car)
(define (tail s) (force (cdr s)))
(define integer-length
(let ()
(define useful
(let loop ((p 256) (n 4))
(cons-stream (cons p n)
(loop (* p p) (* n 2)))))
(define (recur n)
(if (< n 16)
(vector-ref '#(0 1 2 2 3 3 3 3 4 4 4 4 4 4 4 4) n)
(let loop ((s useful) (prev 16))
(let ((z (head s)))
(if (< n (car z))
(+ (cdr z) (recur (quotient n prev)))
(loop (tail s) (car z)))))))
(define (integer-length n)
(if (exact? n)
(if (< n 0)
(recur (- -1 n))
(recur n))
(integer-length (inexact->exact n))))
integer-length))
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