162 lines
4.6 KiB
C++
162 lines
4.6 KiB
C++
/****************************************************************************
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* VCGLib o o *
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* Visual and Computer Graphics Library o o *
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* _ O _ *
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* Copyright(C) 2004 \/)\/ *
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* Visual Computing Lab /\/| *
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* ISTI - Italian National Research Council | *
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* \ *
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* All rights reserved. *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License (http://www.gnu.org/licenses/gpl.txt) *
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* for more details. *
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* *
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****************************************************************************/
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/****************************************************************************
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History
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$Log: not supported by cvs2svn $
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Revision 1.5 2004/07/05 15:49:39 ponchio
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Windows (DevCpp, mingw) port.
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Revision 1.4 2004/07/04 14:23:14 ponchio
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*** empty log message ***
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Revision 1.3 2004/07/02 17:40:30 ponchio
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Debug.
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Revision 1.2 2004/07/01 21:34:04 ponchio
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Rehash bug.
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Revision 1.1 2004/06/24 14:32:45 ponchio
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Moved from wrap/nexus
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Revision 1.1 2004/06/24 14:18:58 ponchio
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Created
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****************************************************************************/
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#include <assert.h>
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#include <iostream>
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#include "mfhash.h"
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using namespace std;
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using namespace nxs;
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bool MFHash::Create(const string &file, unsigned int reserved) {
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if(!buffer.Create(file)) return false;
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buffer.Resize(reserved);
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Bucket empty;
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for(unsigned int i = 0; i < buffer.Size(); i++)
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buffer[i] = empty;
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space = reserved;
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return true;
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}
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bool MFHash::Load(const string &file, unsigned int used) {
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if(!buffer.Load(file)) return false;
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if(used != 0xffffffff) {
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space = buffer.Size() - used;
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} else {
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space = 0;
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for(unsigned int i = 0; i < buffer.Size(); i++)
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if(buffer[i].Empty()) space++;
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}
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return true;
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}
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void MFHash::Delete() {
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buffer.Flush();
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buffer.Delete();
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}
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void MFHash::Resize(unsigned int n) {
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assert(buffer.Size() - space <= n);
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//lets dump actual content
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FILE *fp = tmpfile();
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unsigned int count = 0;
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for(unsigned int i = 0; i < buffer.Size(); i++) {
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Bucket &bucket = buffer[i];
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if(!bucket.Empty()) {
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fwrite(&bucket, sizeof(Bucket), 1, fp);
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++count;
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}
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}
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buffer.Resize(n);
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Clear();
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rewind(fp);
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Bucket bucket;
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for(unsigned int i = 0; i < count; i++) {
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fread(&bucket, sizeof(Bucket), 1, fp);
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Insert(bucket.key, bucket.value, false);
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}
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fclose(fp);
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}
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void MFHash::Insert(unsigned int key, unsigned int value, bool rehash) {
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if(buffer.Size() < 5)
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Resize(5);
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assert(space > 0);
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unsigned int hash_size = buffer.Size();
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unsigned int j = key % hash_size;
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Bucket bucket = buffer[j];
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while(!bucket.Empty()) {
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if(bucket.key == key && bucket.value == value) //already here
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return;
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j++;
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if(j >= hash_size) j = 0;
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bucket = buffer[j];
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}
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buffer[j] = Bucket(key, value);
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space--;
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if(rehash) {
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float ratio = space / (float)buffer.Size();
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if(ratio < 0.4) { //need to resize
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Resize(buffer.Size() * 2 + 3);
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}
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}
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}
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unsigned int MFHash::Count(unsigned int key) {
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unsigned int count = 0;
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unsigned int hash_size = buffer.Size();
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unsigned int j = key % hash_size;
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while(!buffer[j].Empty()) {
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if(buffer[j].key == key)
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count++;
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j++;
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if(j >= hash_size) j = 0;
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}
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return count;
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}
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void MFHash::Clear() {
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Bucket empty;
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for(unsigned int i = 0; i < buffer.Size(); i++)
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buffer[i] = empty;
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space = buffer.Size();
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}
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void MFHash::Close() {
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buffer.Close();
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}
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unsigned int MFHash::Size() {
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return buffer.Size() - space;
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}
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