From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Tue, 25 Jan 2011 15:43:07 +0000 (+0000)
Subject: canon: use base64 not base62
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=ce731a187e10da5e81e81c9d49584c85410389e3;p=ypp-sc-tools.git

canon: use base64 not base62
---

diff --git a/yarrg/canon b/yarrg/canon
index 9ae01e5..35a1778 100755
--- a/yarrg/canon
+++ b/yarrg/canon
@@ -25,12 +25,16 @@ sub alencodenum ($) {
     my $res= '';
     while ($val || !length($res)) {
         # allowing empty strings, reusing "0" for 62, doing base63,
-        # saves 0.5%
-        my $dig= $val % 62;
-        $val= ($val-$dig) / 62;
-        $res = chr($dig + ($dig<10 ? 48 :
-                           $dig<36 ? 97-10 :
-                           $dig<62 ? 65-36 : die $dig)) . $res;
+        # saves 0.5%, compared to base62
+        # actually we do base64 because it'll be faster to compute
+        my $dig= $val & 63;
+        $val >>= 6;
+        $res = ($dig < 10 ? chr(48 + $dig) :
+                $dig < 36 ? chr(97 + $dig - 10) :
+                $dig < 62 ? chr(65 + $dig - 36) :
+                $dig==62 ? '_' :
+                $dig==63 ? '.' : die $dig).
+                $res;
     }
     return $res;
 }