/apps/desktop/libvncserver/zrlepalettehelper.c

 1/*
 2 * Copyright (C) 2002 RealVNC Ltd.  All Rights Reserved.
 3 * Copyright (C) 2003 Sun Microsystems, Inc.
 4 *
 5 * This 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 software 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 software; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
18 * USA.
19 */
20
21#include "zrlepalettehelper.h"
22#include <assert.h>
23#include <string.h>
24
25#define ZRLE_HASH(pix) (((pix) ^ ((pix) >> 17)) & 4095)
26
27void zrlePaletteHelperInit(zrlePaletteHelper *helper)
28{
29  memset(helper->palette, 0, sizeof(helper->palette));
30  memset(helper->index, 255, sizeof(helper->index));
31  memset(helper->key, 0, sizeof(helper->key));
32  helper->size = 0;
33}
34
35void zrlePaletteHelperInsert(zrlePaletteHelper *helper, zrle_U32 pix)
36{
37  if (helper->size < ZRLE_PALETTE_MAX_SIZE) {
38    int i = ZRLE_HASH(pix);
39
40    while (helper->index[i] != 255 && helper->key[i] != pix)
41      i++;
42    if (helper->index[i] != 255) return;
43
44    helper->index[i] = helper->size;
45    helper->key[i] = pix;
46    helper->palette[helper->size] = pix;
47  }
48  helper->size++;
49}
50
51int zrlePaletteHelperLookup(zrlePaletteHelper *helper, zrle_U32 pix)
52{
53  int i = ZRLE_HASH(pix);
54
55  assert(helper->size <= ZRLE_PALETTE_MAX_SIZE);
56  
57  while (helper->index[i] != 255 && helper->key[i] != pix)
58    i++;
59  if (helper->index[i] != 255) return helper->index[i];
60
61  return -1;
62}