From: beware <beware@bircd.org>
Date: Mon, 10 Aug 2015 21:45:41 +0000 (+0000)
Subject: use better hash function (FNV-1a)
X-Git-Url: http://www.lcore.org/git/lcore.git/commitdiff_plain/1a8d0bce39fe4edf7443bde884fefe78412fe521

use better hash function (FNV-1a)

git-svn-id: file:///svnroot/lcore/trunk@143 b1de8a11-f9be-4011-bde0-cc7ace90066a
---

diff --git a/bsearchtree.pas b/bsearchtree.pas
index 9dc355e..9ec804c 100644
--- a/bsearchtree.pas
+++ b/bsearchtree.pas
@@ -37,18 +37,21 @@ procedure cleartree(t:phashtable);
 
 implementation
 
+//FNV-1a hash function
 function makehash(s:ansistring):integer;
 const
   shifter=6;
 var
   a,b:integer;
+  h:longword;
 begin
   result := 0;
   b := length(s);
+  h := 216613626;
   for a := 1 to b do begin
-    result := (result shl shifter) xor byte(s[a]);
+    h := (h xor byte(s[a])) * 16777619;
   end;
-  result := (result xor result shr 16) and (hashtable_size-1);
+  result := h and (hashtable_size-1);
 end;
 
 procedure addtree(t:phashtable;s:ansistring;item:pointer);