diff --git a/rfb/zrleEncode.h b/rfb/zrleEncode.h
new file mode 100644
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--- /dev/null
+++ b/rfb/zrleEncode.h
@@ -0,0 +1,328 @@
+/* Copyright (C) 2002-2004 RealVNC Ltd.  All Rights Reserved.
+ *    
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+//
+// zrleEncode.h - zrle encoding function.
+//
+// This file is #included after having set the following macros:
+// BPP                - 8, 16 or 32
+// EXTRA_ARGS         - optional extra arguments
+// GET_IMAGE_INTO_BUF - gets a rectangle of pixel data into a buffer
+//
+// Note that the buf argument to ZRLE_ENCODE needs to be at least one pixel
+// bigger than the largest tile of pixel data, since the ZRLE encoding
+// algorithm writes to the position one past the end of the pixel data.
+//
+
+#include <rdr/OutStream.h>
+#include <rdr/ZlibOutStream.h>
+#include <assert.h>
+
+namespace rfb {
+
+// CONCAT2E concatenates its arguments, expanding them if they are macros
+
+#ifndef CONCAT2E
+#define CONCAT2(a,b) a##b
+#define CONCAT2E(a,b) CONCAT2(a,b)
+#endif
+
+#ifdef CPIXEL
+#define PIXEL_T rdr::CONCAT2E(U,BPP)
+#define WRITE_PIXEL CONCAT2E(writeOpaque,CPIXEL)
+#define ZRLE_ENCODE CONCAT2E(zrleEncode,CPIXEL)
+#define ZRLE_ENCODE_TILE CONCAT2E(zrleEncodeTile,CPIXEL)
+#define BPPOUT 24
+#else
+#define PIXEL_T rdr::CONCAT2E(U,BPP)
+#define WRITE_PIXEL CONCAT2E(writeOpaque,BPP)
+#define ZRLE_ENCODE CONCAT2E(zrleEncode,BPP)
+#define ZRLE_ENCODE_TILE CONCAT2E(zrleEncodeTile,BPP)
+#define BPPOUT BPP
+#endif
+
+#ifndef ZRLE_ONCE
+#define ZRLE_ONCE
+static const int bitsPerPackedPixel[] = {
+  0, 1, 2, 2, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
+};
+
+// The PaletteHelper class helps us build up the palette from pixel data by
+// storing a reverse index using a simple hash-table
+
+class PaletteHelper {
+public:
+  enum { MAX_SIZE = 127 };
+
+  PaletteHelper()
+  {
+    memset(index, 255, sizeof(index));
+    size = 0;
+  }
+
+  inline int hash(rdr::U32 pix)
+  {
+    return (pix ^ (pix >> 17)) & 4095;
+  }
+
+  inline void insert(rdr::U32 pix)
+  {
+    if (size < MAX_SIZE) {
+      int i = hash(pix);
+      while (index[i] != 255 && key[i] != pix)
+        i++;
+      if (index[i] != 255) return;
+
+      index[i] = size;
+      key[i] = pix;
+      palette[size] = pix;
+    }
+    size++;
+  }
+
+  inline int lookup(rdr::U32 pix)
+  {
+    assert(size <= MAX_SIZE);
+    int i = hash(pix);
+    while (index[i] != 255 && key[i] != pix)
+      i++;
+    if (index[i] != 255) return index[i];
+    return -1;
+  }
+
+  rdr::U32 palette[MAX_SIZE];
+  rdr::U8 index[4096+MAX_SIZE];
+  rdr::U32 key[4096+MAX_SIZE];
+  int size;
+};
+#endif
+
+void ZRLE_ENCODE_TILE (PIXEL_T* data, int w, int h, rdr::OutStream* os);
+
+bool ZRLE_ENCODE (const Rect& r, rdr::OutStream* os,
+                  rdr::ZlibOutStream* zos, void* buf, int maxLen, Rect* actual
+#ifdef EXTRA_ARGS
+                  , EXTRA_ARGS
+#endif
+                  )
+{
+  zos->setUnderlying(os);
+  // RLE overhead is at worst 1 byte per 64x64 (4Kpixel) block
+  int worstCaseLine = r.width() * 64 * (BPPOUT/8) + 1 + r.width() / 64;
+  // Zlib overhead is at worst 6 bytes plus 5 bytes per 32Kbyte block.
+  worstCaseLine += 11 + 5 * (worstCaseLine >> 15);
+  Rect t;
+
+  for (t.tl.y = r.tl.y; t.tl.y < r.br.y; t.tl.y += 64) {
+
+    t.br.y = min(r.br.y, t.tl.y + 64);
+
+    if (os->length() + worstCaseLine > maxLen) {
+      if (t.tl.y == r.tl.y)
+        throw Exception("ZRLE: not enough space for first line?");
+      actual->tl = r.tl;
+      actual->br.x = r.br.x;
+      actual->br.y = t.tl.y;
+      return false;
+    }
+
+    for (t.tl.x = r.tl.x; t.tl.x < r.br.x; t.tl.x += 64) {
+
+      t.br.x = min(r.br.x, t.tl.x + 64);
+
+      GET_IMAGE_INTO_BUF(t,buf);
+
+      ZRLE_ENCODE_TILE((PIXEL_T*)buf, t.width(), t.height(), zos);
+    }
+
+    zos->flush();
+  }
+  return true;
+}
+
+
+void ZRLE_ENCODE_TILE (PIXEL_T* data, int w, int h, rdr::OutStream* os)
+{
+  // First find the palette and the number of runs
+
+  PaletteHelper ph;
+
+  int runs = 0;
+  int singlePixels = 0;
+
+  PIXEL_T* ptr = data;
+  PIXEL_T* end = ptr + h * w;
+  *end = ~*(end-1); // one past the end is different so the while loop ends
+
+  while (ptr < end) {
+    PIXEL_T pix = *ptr;
+    if (*++ptr != pix) {
+      singlePixels++;
+    } else {
+      while (*++ptr == pix) ;
+      runs++;
+    }
+    ph.insert(pix);
+  }
+
+  //fprintf(stderr,"runs %d, single pixels %d, paletteSize %d\n",
+  //        runs, singlePixels, ph.size);
+
+  // Solid tile is a special case
+
+  if (ph.size == 1) {
+    os->writeU8(1);
+    os->WRITE_PIXEL(ph.palette[0]);
+    return;
+  }
+
+  // Try to work out whether to use RLE and/or a palette.  We do this by
+  // estimating the number of bytes which will be generated and picking the
+  // method which results in the fewest bytes.  Of course this may not result
+  // in the fewest bytes after compression...
+
+  bool useRle = false;
+  bool usePalette = false;
+
+  int estimatedBytes = w * h * (BPPOUT/8); // start assuming raw
+
+  int plainRleBytes = ((BPPOUT/8)+1) * (runs + singlePixels);
+
+  if (plainRleBytes < estimatedBytes) {
+    useRle = true;
+    estimatedBytes = plainRleBytes;
+  }
+
+  if (ph.size < 128) {
+    int paletteRleBytes = (BPPOUT/8) * ph.size + 2 * runs + singlePixels;
+
+    if (paletteRleBytes < estimatedBytes) {
+      useRle = true;
+      usePalette = true;
+      estimatedBytes = paletteRleBytes;
+    }
+
+    if (ph.size < 17) {
+      int packedBytes = ((BPPOUT/8) * ph.size +
+                         w * h * bitsPerPackedPixel[ph.size-1] / 8);
+
+      if (packedBytes < estimatedBytes) {
+        useRle = false;
+        usePalette = true;
+        estimatedBytes = packedBytes;
+      }
+    }
+  }
+
+  if (!usePalette) ph.size = 0;
+
+  os->writeU8((useRle ? 128 : 0) | ph.size);
+
+  for (int i = 0; i < ph.size; i++) {
+    os->WRITE_PIXEL(ph.palette[i]);
+  }
+
+  if (useRle) {
+
+    PIXEL_T* ptr = data;
+    PIXEL_T* end = ptr + w * h;
+    PIXEL_T* runStart;
+    PIXEL_T pix;
+    while (ptr < end) {
+      runStart = ptr;
+      pix = *ptr++;
+      while (*ptr == pix && ptr < end)
+        ptr++;
+      int len = ptr - runStart;
+      if (len <= 2 && usePalette) {
+        int index = ph.lookup(pix);
+        if (len == 2)
+          os->writeU8(index);
+        os->writeU8(index);
+        continue;
+      }
+      if (usePalette) {
+        int index = ph.lookup(pix);
+        os->writeU8(index | 128);
+      } else {
+        os->WRITE_PIXEL(pix);
+      }
+      len -= 1;
+      while (len >= 255) {
+        os->writeU8(255);
+        len -= 255;
+      }
+      os->writeU8(len);
+    }
+
+  } else {
+
+    // no RLE
+
+    if (usePalette) {
+
+      // packed pixels
+
+      assert (ph.size < 17);
+
+      int bppp = bitsPerPackedPixel[ph.size-1];
+
+      PIXEL_T* ptr = data;
+
+      for (int i = 0; i < h; i++) {
+        rdr::U8 nbits = 0;
+        rdr::U8 byte = 0;
+
+        PIXEL_T* eol = ptr + w;
+
+        while (ptr < eol) {
+          PIXEL_T pix = *ptr++;
+          rdr::U8 index = ph.lookup(pix);
+          byte = (byte << bppp) | index;
+          nbits += bppp;
+          if (nbits >= 8) {
+            os->writeU8(byte);
+            nbits = 0;
+          }
+        }
+        if (nbits > 0) {
+          byte <<= 8 - nbits;
+          os->writeU8(byte);
+        }
+      }
+    } else {
+
+      // raw
+
+#ifdef CPIXEL
+      for (PIXEL_T* ptr = data; ptr < data+w*h; ptr++) {
+        os->WRITE_PIXEL(*ptr);
+      }
+#else
+      os->writeBytes(data, w*h*(BPP/8));
+#endif
+    }
+  }
+}
+
+#undef PIXEL_T
+#undef WRITE_PIXEL
+#undef ZRLE_ENCODE
+#undef ZRLE_ENCODE_TILE
+#undef BPPOUT
+}