/*
* zlib.c
*
* Routines to implement zlib based encoding (deflate).
*/
/*
* Copyright (C) 2000 Tridia Corporation. All Rights Reserved.
* Copyright (C) 1999 AT&T Laboratories Cambridge. 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.
*
* For the latest source code, please check:
*
* http://www.developVNC.org/
*
* or send email to feedback@developvnc.org.
*/
#include <rfb/rfb.h>
/*
* zlibBeforeBuf contains pixel data in the client's format.
* zlibAfterBuf contains the zlib (deflated) encoding version.
* If the zlib compressed/encoded version is
* larger than the raw data or if it exceeds zlibAfterBufSize then
* raw encoding is used instead.
*/
/*
* Out of lazyiness, we use thread local storage for zlib as we did for
* tight. N.B. ZRLE does it the traditional way with per-client storage
* (and so at least ZRLE will work threaded on older systems.)
*/
#if LIBVNCSERVER_HAVE_LIBPTHREAD && LIBVNCSERVER_HAVE_TLS && !defined(TLS) && defined(__linux__)
#define TLS __thread
#endif
#ifndef TLS
#define TLS
#endif
static TLS int zlibBeforeBufSize = 0;
static TLS char *zlibBeforeBuf = NULL;
static TLS int zlibAfterBufSize = 0;
static TLS char *zlibAfterBuf = NULL;
static TLS int zlibAfterBufLen = 0;
void rfbZlibCleanup(rfbScreenInfoPtr screen)
{
if (zlibBeforeBufSize) {
free(zlibBeforeBuf);
zlibBeforeBufSize=0;
}
if (zlibAfterBufSize) {
zlibAfterBufSize=0;
free(zlibAfterBuf);
}
}
/*
* rfbSendOneRectEncodingZlib - send a given rectangle using one Zlib
* rectangle encoding.
*/
static rfbBool
rfbSendOneRectEncodingZlib(rfbClientPtr cl,
int x,
int y,
int w,
int h)
{
rfbFramebufferUpdateRectHeader rect;
rfbZlibHeader hdr;
int deflateResult;
int previousOut;
int i;
char *fbptr = (cl->scaledScreen->frameBuffer + (cl->scaledScreen->paddedWidthInBytes * y)
+ (x * (cl->scaledScreen->bitsPerPixel / 8)));
int maxRawSize;
int maxCompSize;
maxRawSize = (cl->scaledScreen->width * cl->scaledScreen->height
* (cl->format.bitsPerPixel / 8));
if (zlibBeforeBufSize < maxRawSize) {
zlibBeforeBufSize = maxRawSize;
if (zlibBeforeBuf == NULL)
zlibBeforeBuf = (char *)malloc(zlibBeforeBufSize);
else
zlibBeforeBuf = (char *)realloc(zlibBeforeBuf, zlibBeforeBufSize);
}
/* zlib compression is not useful for very small data sets.
* So, we just send these raw without any compression.
*/
if (( w * h * (cl->scaledScreen->bitsPerPixel / 8)) <
VNC_ENCODE_ZLIB_MIN_COMP_SIZE ) {
int result;
/* The translation function (used also by the in raw encoding)
* requires 4/2/1 byte alignment in the output buffer (which is
* updateBuf for the raw encoding) based on the bitsPerPixel of
* the viewer/client. This prevents SIGBUS errors on some
* architectures like SPARC, PARISC...
*/
if (( cl->format.bitsPerPixel > 8 ) &&
( cl->ublen % ( cl->format.bitsPerPixel / 8 )) != 0 ) {
if (!rfbSendUpdateBuf(cl))
return FALSE;
}
result = rfbSendRectEncodingRaw(cl, x, y, w, h);
return result;
}
/*
* zlib requires output buffer to be slightly larger than the input
* buffer, in the worst case.
*/
maxCompSize = maxRawSize + (( maxRawSize + 99 ) / 100 ) + 12;
if (zlibAfterBufSize < maxCompSize) {
zlibAfterBufSize = maxCompSize;
if (zlibAfterBuf == NULL)
zlibAfterBuf = (char *)malloc(zlibAfterBufSize);
else
zlibAfterBuf = (char *)realloc(zlibAfterBuf, zlibAfterBufSize);
}
/*
* Convert pixel data to client format.
*/
(*cl->translateFn)(cl->translateLookupTable, &cl->screen->serverFormat,
&cl->format, fbptr, zlibBeforeBuf,
cl->scaledScreen->paddedWidthInBytes, w, h);
cl->compStream.next_in = ( Bytef * )zlibBeforeBuf;
cl->compStream.avail_in = w * h * (cl->format.bitsPerPixel / 8);
cl->compStream.next_out = ( Bytef * )zlibAfterBuf;
cl->compStream.avail_out = maxCompSize;
cl->compStream.data_type = Z_BINARY;
/* Initialize the deflation state. */
if ( cl->compStreamInited == FALSE ) {
cl->compStream.total_in = 0;
cl->compStream.total_out = 0;
cl->compStream.zalloc = Z_NULL;
cl->compStream.zfree = Z_NULL;
cl->compStream.opaque = Z_NULL;
deflateInit2( &(cl->compStream),
cl->zlibCompressLevel,
Z_DEFLATED,
MAX_WBITS,
MAX_MEM_LEVEL,
Z_DEFAULT_STRATEGY );
/* deflateInit( &(cl->compStream), Z_BEST_COMPRESSION ); */
/* deflateInit( &(cl->compStream), Z_BEST_SPEED ); */
cl->compStreamInited = TRUE;
}
previousOut = cl->compStream.total_out;
/* Perform the compression here. */
deflateResult = deflate( &(cl->compStream), Z_SYNC_FLUSH );
/* Find the total size of the resulting compressed data. */
zlibAfterBufLen = cl->compStream.total_out - previousOut;
if ( deflateResult != Z_OK ) {
rfbErr("zlib deflation error: %s\n", cl->compStream.msg);
return FALSE;
}
/* Note that it is not possible to switch zlib parameters based on
* the results of the compression pass. The reason is
* that we rely on the compressor and decompressor states being
* in sync. Compressing and then discarding the results would
* cause lose of synchronization.
*/
/* Update statics */
rfbStatRecordEncodingSent(cl, rfbEncodingZlib, sz_rfbFramebufferUpdateRectHeader + sz_rfbZlibHeader + zlibAfterBufLen,
+ w * (cl->format.bitsPerPixel / 8) * h);
if (cl->ublen + sz_rfbFramebufferUpdateRectHeader + sz_rfbZlibHeader
> UPDATE_BUF_SIZE)
{
if (!rfbSendUpdateBuf(cl))
return FALSE;
}
rect.r.x = Swap16IfLE(x);
rect.r.y = Swap16IfLE(y);
rect.r.w = Swap16IfLE(w);
rect.r.h = Swap16IfLE(h);
rect.encoding = Swap32IfLE(rfbEncodingZlib);
memcpy(&cl->updateBuf[cl->ublen], (char *)&rect,
sz_rfbFramebufferUpdateRectHeader);
cl->ublen += sz_rfbFramebufferUpdateRectHeader;
hdr.nBytes = Swap32IfLE(zlibAfterBufLen);
memcpy(&cl->updateBuf[cl->ublen], (char *)&hdr, sz_rfbZlibHeader);
cl->ublen += sz_rfbZlibHeader;
for (i = 0; i < zlibAfterBufLen;) {
int bytesToCopy = UPDATE_BUF_SIZE - cl->ublen;
if (i + bytesToCopy > zlibAfterBufLen) {
bytesToCopy = zlibAfterBufLen - i;
}
memcpy(&cl->updateBuf[cl->ublen], &zlibAfterBuf[i], bytesToCopy);
cl->ublen += bytesToCopy;
i += bytesToCopy;
if (cl->ublen == UPDATE_BUF_SIZE) {
if (!rfbSendUpdateBuf(cl))
return FALSE;
}
}
return TRUE;
}
/*
* rfbSendRectEncodingZlib - send a given rectangle using one or more
* Zlib encoding rectangles.
*/
rfbBool
rfbSendRectEncodingZlib(rfbClientPtr cl,
int x,
int y,
int w,
int h)
{
int maxLines;
int linesRemaining;
rfbRectangle partialRect;
partialRect.x = x;
partialRect.y = y;
partialRect.w = w;
partialRect.h = h;
/* Determine maximum pixel/scan lines allowed per rectangle. */
maxLines = ( ZLIB_MAX_SIZE(w) / w );
/* Initialize number of scan lines left to do. */
linesRemaining = h;
/* Loop until all work is done. */
while ( linesRemaining > 0 ) {
int linesToComp;
if ( maxLines < linesRemaining )
linesToComp = maxLines;
else
linesToComp = linesRemaining;
partialRect.h = linesToComp;
/* Encode (compress) and send the next rectangle. */
if ( ! rfbSendOneRectEncodingZlib( cl,
partialRect.x,
partialRect.y,
partialRect.w,
partialRect.h )) {
return FALSE;
}
/* Technically, flushing the buffer here is not extrememly
* efficient. However, this improves the overall throughput
* of the system over very slow networks. By flushing
* the buffer with every maximum size zlib rectangle, we
* improve the pipelining usage of the server CPU, network,
* and viewer CPU components. Insuring that these components
* are working in parallel actually improves the performance
* seen by the user.
* Since, zlib is most useful for slow networks, this flush
* is appropriate for the desired behavior of the zlib encoding.
*/
if (( cl->ublen > 0 ) &&
( linesToComp == maxLines )) {
if (!rfbSendUpdateBuf(cl)) {
return FALSE;
}
}
/* Update remaining and incremental rectangle location. */
linesRemaining -= linesToComp;
partialRect.y += linesToComp;
}
return TRUE;
}