text: /*
   * QEMU VNC display driver: zlib encoding
   *
   * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
   * Copyright (C) 2006 Fabrice Bellard
   * Copyright (C) 2009 Red Hat, Inc
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include "vnc.h"
  
  #define ZALLOC_ALIGNMENT 16
  
  void *vnc_zlib_zalloc(void *x, unsigned items, unsigned size)
  {
      void *p;
  
      size *= items;
      size = (size + ZALLOC_ALIGNMENT - 1) & ~(ZALLOC_ALIGNMENT - 1);
  
      p = g_malloc0(size);
  
      return (p);
  }
  
  void vnc_zlib_zfree(void *x, void *addr)
  {
      g_free(addr);
  }
  
  static void vnc_zlib_start(VncState *vs)
  {
      buffer_reset(&vs->zlib.zlib);
  
      // make the output buffer be the zlib buffer, so we can compress it later
      vs->zlib.tmp = vs->output;
      vs->output = vs->zlib.zlib;
  }
  
  static int vnc_zlib_stop(VncState *vs)
  {
      z_streamp zstream = &vs->zlib.stream;
      int previous_out;
  
      // switch back to normal output/zlib buffers
      vs->zlib.zlib = vs->output;
      vs->output = vs->zlib.tmp;
  
      // compress the zlib buffer
  
      // initialize the stream
      // XXX need one stream per session
      if (zstream->opaque != vs) {
          int err;
  
          VNC_DEBUG("VNC: initializing zlib stream\n");
          VNC_DEBUG("VNC: opaque = %p | vs = %p\n", zstream->opaque, vs);
          zstream->zalloc = vnc_zlib_zalloc;
          zstream->zfree = vnc_zlib_zfree;
  
          err = deflateInit2(zstream, vs->tight.compression, Z_DEFLATED, MAX_WBITS,
                             MAX_MEM_LEVEL, Z_DEFAULT_STRATEGY);
  
          if (err != Z_OK) {
              fprintf(stderr, "VNC: error initializing zlib\n");
              return -1;
          }
  
          vs->zlib.level = vs->tight.compression;
          zstream->opaque = vs;
      }
  
      if (vs->tight.compression != vs->zlib.level) {
          if (deflateParams(zstream, vs->tight.compression,
                            Z_DEFAULT_STRATEGY) != Z_OK) {
              return -1;
          }
          vs->zlib.level = vs->tight.compression;
      }
  
      // reserve memory in output buffer
      buffer_reserve(&vs->output, vs->zlib.zlib.offset + 64);
  
      // set pointers
      zstream->next_in = vs->zlib.zlib.buffer;
      zstream->avail_in = vs->zlib.zlib.offset;
      zstream->next_out = vs->output.buffer + vs->output.offset;
      zstream->avail_out = vs->output.capacity - vs->output.offset;
      previous_out = zstream->avail_out;
      zstream->data_type = Z_BINARY;
  
      // start encoding
      if (deflate(zstream, Z_SYNC_FLUSH) != Z_OK) {
          fprintf(stderr, "VNC: error during zlib compression\n");
          return -1;
      }
  
      vs->output.offset = vs->output.capacity - zstream->avail_out;
      return previous_out - zstream->avail_out;
  }
  
  int vnc_zlib_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
  {
      int old_offset, new_offset, bytes_written;
  
      vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_ZLIB);
  
      // remember where we put in the follow-up size
      old_offset = vs->output.offset;
      vnc_write_s32(vs, 0);
  
      // compress the stream
      vnc_zlib_start(vs);
      vnc_raw_send_framebuffer_update(vs, x, y, w, h);
      bytes_written = vnc_zlib_stop(vs);
  
      if (bytes_written == -1)
          return 0;
  
      // hack in the size
      new_offset = vs->output.offset;
      vs->output.offset = old_offset;
      vnc_write_u32(vs, bytes_written);
      vs->output.offset = new_offset;
  
      return 1;
  }
  
  void vnc_zlib_clear(VncState *vs)
  {
      if (vs->zlib.stream.opaque) {
          deflateEnd(&vs->zlib.stream);
      }
      buffer_free(&vs->zlib.zlib);
  }
  