[3365] | 1 | /**************************************************************************
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| 2 | *
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| 3 | * FragLevelConvert.cpp -- converting between fragment and document numbers
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| 4 | * Copyright (C) 1999 Rodger McNab
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or modify
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| 7 | * it under the terms of the GNU General Public License as published by
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| 8 | * the Free Software Foundation; either version 2 of the License, or
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| 9 | * (at your option) any later version.
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| 10 | *
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| 11 | * This program is distributed in the hope that it will be useful,
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | * GNU General Public License for more details.
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| 15 | *
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| 16 | * You should have received a copy of the GNU General Public License
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| 17 | * along with this program; if not, write to the Free Software
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| 18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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| 19 | *
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| 20 | **************************************************************************/
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| 21 |
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| 22 | #include "FragLevelConvert.h"
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| 23 | #include "bitio_m_stdio.h"
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| 24 | #include "bitio_gen.h"
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| 25 |
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| 26 |
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| 27 | FragLevelConvert::FragLevelConvert () {
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| 28 | numFrags = 0;
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| 29 | numLevelDocs = 0;
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| 30 | }
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| 31 |
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| 32 | bool FragLevelConvert::Read (FILE *invfFile,
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| 33 | unsigned long levelPtr,
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| 34 | unsigned long _numFrags,
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| 35 | unsigned long _numLevelDocs) {
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| 36 | levelStarts.erase (levelStarts.begin(), levelStarts.end());
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| 37 | numFrags = _numFrags;
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| 38 | numLevelDocs = _numLevelDocs;
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| 39 |
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| 40 | // seek to the appropriate place in the inverted file
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| 41 | fseek (invfFile, levelPtr, SEEK_SET);
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| 42 |
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| 43 | stdio_bitio_buffer buffer(invfFile);
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| 44 |
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| 45 | unsigned long pTag = numLevelDocs*2;
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| 46 | unsigned long B = BIO_Bblock_Init (numFrags+pTag, pTag);
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| 47 | unsigned long fragNum = 0;
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| 48 | unsigned long i;
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[9613] | 49 | for (i=0; i<numLevelDocs; ++i) {
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[3365] | 50 | unsigned long delta = buffer.bblock_decode (B, NULL)-1;
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| 51 | fragNum += delta;
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| 52 |
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| 53 | levelStarts.push_back (fragNum);
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| 54 |
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| 55 | // ignore end, assume every fragment is in a level
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| 56 | delta = buffer.bblock_decode (B, NULL)-1;
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| 57 | fragNum += delta;
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| 58 | }
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| 59 |
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| 60 | // fragNum would be the starting fragment of the next document
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| 61 | // if there was one
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| 62 | levelStarts.push_back (fragNum);
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| 63 |
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| 64 | if (fragNum != _numFrags) {
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| 65 | cerr << "last frag num:"<<fragNum<<" != num frags:"<<_numFrags<<endl;
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| 66 | }
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| 67 | buffer.done();
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| 68 |
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| 69 | return true;
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| 70 | }
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| 71 |
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| 72 | bool FragLevelConvert::FragToLevel (unsigned long fragNum,
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| 73 | unsigned long &levelDocNum) const {
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| 74 | // do binary search for something containing this fragment number
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| 75 | unsigned long low = 1, high = numLevelDocs;
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| 76 | unsigned long mid;
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| 77 |
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| 78 | while ((mid = (low+high)/2) >= 1 && low <= high) {
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| 79 | if (fragNum > levelStarts[mid]) low = mid+1;
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| 80 | else if (fragNum <= levelStarts[mid-1]) high = mid-1;
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| 81 | else {
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| 82 | levelDocNum = mid;
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| 83 | return true;
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| 84 | }
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| 85 | }
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| 86 | return false;
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| 87 | }
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| 88 |
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| 89 |
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| 90 | bool FragLevelConvert::LevelToLevel (FragLevelConvert sectionLevelConvert,
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| 91 | unsigned long levelNum, unsigned long &DocNum) {
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| 92 |
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| 93 | if (levelNum==1) {
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| 94 | DocNum=1;
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| 95 | return true;
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| 96 | }
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| 97 | unsigned long levelfragnum = sectionLevelConvert.levelStarts[levelNum-1]+1;
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| 98 |
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| 99 | if (FragToLevel(levelfragnum, DocNum)) {
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| 100 | return true;
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| 101 | }
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| 102 | return false;
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| 103 |
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| 104 |
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| 105 | }
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