apps/konsole/src/BlockArray.h

   1 /*
   2     This file is part of Konsole, an X terminal.
   3     Copyright 2000 by Stephan Kulow <coolo@kde.org>
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18     02110-1301  USA.
  19 */
  20
  21 #ifndef BLOCKARRAY_H
  22 #define BLOCKARRAY_H
  23
  24 #include <unistd.h>
  25
  26 //#error Do not use in KDE 2.1
  27
  28 #define BlockSize (1 << 12)
  29 #define ENTRIES   ((BlockSize - sizeof(size_t) ) / sizeof(unsigned char))
  30
  31 namespace Konsole
  32 {
  33
  34 struct Block {
  35     Block() { size = 0; }
  36     unsigned char data[ENTRIES];
  37     size_t size;
  38 };
  39
  40 // ///////////////////////////////////////////////////////
  41
  42 class BlockArray {
  43 public:
  44     /**
  45     * Creates a history file for holding
  46     * maximal size blocks. If more blocks
  47     * are requested, then it drops earlier
  48     * added ones.
  49     */
  50     BlockArray();
  51
  52     /// destructor
  53     ~BlockArray();
  54
  55     /**
  56     * adds the Block at the end of history.
  57     * This may drop other blocks.
  58     *
  59     * The ownership on the block is transfered.
  60     * An unique index number is returned for accessing
  61     * it later (if not yet dropped then)
  62     *
  63     * Note, that the block may be dropped completely
  64     * if history is turned off.
  65     */
  66     size_t append(Block *block);
  67
  68     /**
  69     * gets the block at the index. Function may return
  70     * 0 if the block isn't available any more.
  71     *
  72     * The returned block is strictly readonly as only
  73     * maped in memory - and will be invalid on the next
  74     * operation on this class.
  75     */
  76     const Block *at(size_t index);
  77
  78     /**
  79     * reorders blocks as needed. If newsize is null,
  80     * the history is emptied completely. The indices
  81     * returned on append won't change their semantic,
  82     * but they may not be valid after this call.
  83     */
  84     bool setHistorySize(size_t newsize);
  85
  86     size_t newBlock();
  87
  88     Block *lastBlock() const;
  89
  90     /**
  91     * Convenient function to set the size in KBytes
  92     * instead of blocks
  93     */
  94     bool setSize(size_t newsize);
  95
  96     size_t len() const { return length; }
  97
  98     bool has(size_t index) const;
  99
 100     size_t getCurrent() const { return current; }
 101
 102 private:
 103     void unmap();
 104     void increaseBuffer();
 105     void decreaseBuffer(size_t newsize);
 106
 107     size_t size;
 108     // current always shows to the last inserted block
 109     size_t current;
 110     size_t index;
 111
 112     Block *lastmap;
 113     size_t lastmap_index;
 114     Block *lastblock;
 115
 116     int ion;
 117     size_t length;
 118
 119 };
 120
 121 }
 122
 123 #endif