311 lines
7.4 KiB
C++
311 lines
7.4 KiB
C++
//
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// Copyright (C) 2002 RealVNC Ltd. All Rights Reserved.
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//
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// This 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 software 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 for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this software; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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//
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// zrleEncode.h - zrle encoding function.
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//
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// Before including this file, you must define a number of CPP macros.
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//
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// BPP should be 8, 16 or 32 depending on the bits per pixel.
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// GET_IMAGE_INTO_BUF should be some code which gets a rectangle of pixel data
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// into the given buffer. EXTRA_ARGS can be defined to pass any other
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// arguments needed by GET_IMAGE_INTO_BUF.
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//
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// Note that the buf argument to ZRLE_ENCODE needs to be at least one pixel
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// bigger than the largest tile of pixel data, since the ZRLE encoding
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// algorithm writes to the position one past the end of the pixel data.
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//
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#include <rdr/OutStream.h>
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#include <assert.h>
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using namespace rdr;
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/* __RFB_CONCAT2 concatenates its two arguments. __RFB_CONCAT2E does the same
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but also expands its arguments if they are macros */
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#ifndef __RFB_CONCAT2E
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#define __RFB_CONCAT2(a,b) a##b
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#define __RFB_CONCAT2E(a,b) __RFB_CONCAT2(a,b)
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#endif
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#ifdef CPIXEL
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#define PIXEL_T __RFB_CONCAT2E(rdr::U,BPP)
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#define WRITE_PIXEL __RFB_CONCAT2E(writeOpaque,CPIXEL)
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#define ZRLE_ENCODE __RFB_CONCAT2E(zrleEncode,CPIXEL)
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#define ZRLE_ENCODE_TILE __RFB_CONCAT2E(zrleEncodeTile,CPIXEL)
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#define BPPOUT 24
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#else
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#define PIXEL_T __RFB_CONCAT2E(rdr::U,BPP)
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#define WRITE_PIXEL __RFB_CONCAT2E(writeOpaque,BPP)
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#define ZRLE_ENCODE __RFB_CONCAT2E(zrleEncode,BPP)
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#define ZRLE_ENCODE_TILE __RFB_CONCAT2E(zrleEncodeTile,BPP)
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#define BPPOUT BPP
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#endif
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#ifndef ZRLE_ONCE
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#define ZRLE_ONCE
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static const int bitsPerPackedPixel[] = {
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0, 1, 2, 2, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
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};
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// The PaletteHelper class helps us build up the palette from pixel data by
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// storing a reverse index using a simple hash-table
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class PaletteHelper {
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public:
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enum { MAX_SIZE = 127 };
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PaletteHelper()
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{
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memset(index, 255, sizeof(index));
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size = 0;
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}
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inline int hash(rdr::U32 pix)
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{
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return (pix ^ (pix >> 17)) & 4095;
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}
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inline void insert(rdr::U32 pix)
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{
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if (size < MAX_SIZE) {
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int i = hash(pix);
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while (index[i] != 255 && key[i] != pix)
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i++;
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if (index[i] != 255) return;
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index[i] = size;
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key[i] = pix;
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palette[size] = pix;
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}
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size++;
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}
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inline int lookup(rdr::U32 pix)
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{
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assert(size <= MAX_SIZE);
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int i = hash(pix);
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while (index[i] != 255 && key[i] != pix)
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i++;
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if (index[i] != 255) return index[i];
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return -1;
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}
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rdr::U32 palette[MAX_SIZE];
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rdr::U8 index[4096+MAX_SIZE];
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rdr::U32 key[4096+MAX_SIZE];
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int size;
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};
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#endif
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void ZRLE_ENCODE_TILE (PIXEL_T* data, int w, int h, rdr::OutStream* os);
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void ZRLE_ENCODE (int x, int y, int w, int h, rdr::OutStream* os,
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rdr::ZlibOutStream* zos, void* buf
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EXTRA_ARGS
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)
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{
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zos->setUnderlying(os);
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for (int ty = y; ty < y+h; ty += rfbZRLETileHeight) {
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int th = rfbZRLETileHeight;
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if (th > y+h-ty) th = y+h-ty;
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for (int tx = x; tx < x+w; tx += rfbZRLETileWidth) {
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int tw = rfbZRLETileWidth;
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if (tw > x+w-tx) tw = x+w-tx;
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GET_IMAGE_INTO_BUF(tx,ty,tw,th,buf);
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ZRLE_ENCODE_TILE((PIXEL_T*)buf, tw, th, zos);
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}
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}
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zos->flush();
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}
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void ZRLE_ENCODE_TILE (PIXEL_T* data, int w, int h, rdr::OutStream* os)
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{
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// First find the palette and the number of runs
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PaletteHelper ph;
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int runs = 0;
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int singlePixels = 0;
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PIXEL_T* ptr = data;
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PIXEL_T* end = ptr + h * w;
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*end = ~*(end-1); // one past the end is different so the while loop ends
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while (ptr < end) {
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PIXEL_T pix = *ptr;
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if (*++ptr != pix) {
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singlePixels++;
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} else {
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while (*++ptr == pix) ;
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runs++;
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}
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ph.insert(pix);
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}
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//fprintf(stderr,"runs %d, single pixels %d, paletteSize %d\n",
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// runs, singlePixels, ph.size);
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// Solid tile is a special case
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if (ph.size == 1) {
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os->writeU8(1);
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os->WRITE_PIXEL(ph.palette[0]);
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return;
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}
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// Try to work out whether to use RLE and/or a palette. We do this by
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// estimating the number of bytes which will be generated and picking the
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// method which results in the fewest bytes. Of course this may not result
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// in the fewest bytes after compression...
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bool useRle = false;
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bool usePalette = false;
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int estimatedBytes = w * h * (BPPOUT/8); // start assuming raw
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int plainRleBytes = ((BPPOUT/8)+1) * (runs + singlePixels);
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if (plainRleBytes < estimatedBytes) {
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useRle = true;
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estimatedBytes = plainRleBytes;
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}
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if (ph.size < 128) {
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int paletteRleBytes = (BPPOUT/8) * ph.size + 2 * runs + singlePixels;
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if (paletteRleBytes < estimatedBytes) {
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useRle = true;
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usePalette = true;
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estimatedBytes = paletteRleBytes;
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}
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if (ph.size < 17) {
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int packedBytes = ((BPPOUT/8) * ph.size +
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w * h * bitsPerPackedPixel[ph.size-1] / 8);
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if (packedBytes < estimatedBytes) {
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useRle = false;
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usePalette = true;
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estimatedBytes = packedBytes;
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}
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}
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}
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if (!usePalette) ph.size = 0;
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os->writeU8((useRle ? 128 : 0) | ph.size);
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for (int i = 0; i < ph.size; i++) {
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os->WRITE_PIXEL(ph.palette[i]);
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}
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if (useRle) {
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PIXEL_T* ptr = data;
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PIXEL_T* end = ptr + w * h;
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PIXEL_T* runStart;
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PIXEL_T pix;
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while (ptr < end) {
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runStart = ptr;
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pix = *ptr++;
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while (*ptr == pix && ptr < end)
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ptr++;
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int len = ptr - runStart;
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if (len <= 2 && usePalette) {
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int index = ph.lookup(pix);
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if (len == 2)
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os->writeU8(index);
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os->writeU8(index);
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continue;
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}
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if (usePalette) {
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int index = ph.lookup(pix);
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os->writeU8(index | 128);
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} else {
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os->WRITE_PIXEL(pix);
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}
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len -= 1;
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while (len >= 255) {
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os->writeU8(255);
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len -= 255;
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}
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os->writeU8(len);
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}
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} else {
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// no RLE
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if (usePalette) {
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// packed pixels
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assert (ph.size < 17);
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int bppp = bitsPerPackedPixel[ph.size-1];
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PIXEL_T* ptr = data;
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for (int i = 0; i < h; i++) {
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U8 nbits = 0;
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U8 byte = 0;
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PIXEL_T* eol = ptr + w;
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while (ptr < eol) {
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PIXEL_T pix = *ptr++;
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U8 index = ph.lookup(pix);
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byte = (byte << bppp) | index;
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nbits += bppp;
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if (nbits >= 8) {
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os->writeU8(byte);
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nbits = 0;
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}
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}
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if (nbits > 0) {
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byte <<= 8 - nbits;
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os->writeU8(byte);
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}
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}
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} else {
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// raw
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#ifdef CPIXEL
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for (PIXEL_T* ptr = data; ptr < data+w*h; ptr++) {
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os->WRITE_PIXEL(*ptr);
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}
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#else
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os->writeBytes(data, w*h*(BPP/8));
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#endif
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}
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}
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}
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#undef PIXEL_T
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#undef WRITE_PIXEL
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#undef ZRLE_ENCODE
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#undef ZRLE_ENCODE_TILE
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#undef BPPOUT
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