From: Stephen Adams <edu/mit/csail/zurich/adams>
Date: Tue, 8 Jul 1997 01:22:28 +0000 (+0000)
Subject: Changes in INT:->STRING to improve performance.  30% faster for huge
X-Git-Tag: 20090517-FFI~5084
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=1df7e26e9f5a743d37d3d56673d725c67437568f;p=mit-scheme.git

Changes in INT:->STRING to improve performance.  30% faster for huge
bignums (10^1000), up to 2x-3x faster for small bignums (up to
10^100), slightly faster for fixnums.

 . Use a local version of DIGIT->CHAR since we don't need to check the
   radix.

 . PRINT-FIXNUM modified to be useful for generating digits in the
   middle of a number.

 . PRINT-MEDIUM and PRINT-LARGE work in units of several digits, the
   length of a unit pre-computed so that a unit can be printed using
   fixnum arithmetic.

 . PRINT-MEDIUM chops off groups of digits that can be printed by
   PRINT-FIXNUM.  The microcode primitive LISTIFY-BIGNUM is no longer
   used.

 . PRINT-LARGE has a special check to try to avoid the last multiply
   in building the power stack (which is asymptotically 2/3 of the
   cost of building the stack).  The recursion termination check is
   generalized to also catch sequences of digits with enough leading
   zeroes to be formatted by PRINT-FIXNUM (this can double the speed
   of printing numbers with many zeros).
---

diff --git a/v7/src/runtime/arith.scm b/v7/src/runtime/arith.scm
index 9c1ccb5a9..0c3ec67de 100644
--- a/v7/src/runtime/arith.scm
+++ b/v7/src/runtime/arith.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Id: arith.scm,v 1.41 1997/07/07 20:24:45 adams Exp $
+$Id: arith.scm,v 1.42 1997/07/08 01:22:28 adams Exp $
 
 Copyright (c) 1989-97 Massachusetts Institute of Technology
 
@@ -344,7 +344,7 @@ MIT in each case. |#
   (set! *maximum-fixnum-radix-powers*
 	(make-initialized-vector 37
 	  (lambda (radix)
-	    (and (fix:> radix 2)
+	    (and (fix:>= radix 2)
 		 (let loop ((digits 0) (factor 1))
 		   (let ((nf (int:* factor radix)))
 		     (if (fix:fixnum? nf)