4
* Routines to implement zlib based encoding (deflate).
8
* Copyright (C) 2000 Tridia Corporation. All Rights Reserved.
9
* Copyright (C) 1999 AT&T Laboratories Cambridge. All Rights Reserved.
11
* This is free software; you can redistribute it and/or modify
12
* it under the terms of the GNU General Public License as published by
13
* the Free Software Foundation; either version 2 of the License, or
14
* (at your option) any later version.
16
* This software is distributed in the hope that it will be useful,
17
* but WITHOUT ANY WARRANTY; without even the implied warranty of
18
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19
* GNU General Public License for more details.
21
* You should have received a copy of the GNU General Public License
22
* along with this software; if not, write to the Free Software
23
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
26
* For the latest source code, please check:
28
* http://www.developVNC.org/
30
* or send email to feedback@developvnc.org.
36
* zlibBeforeBuf contains pixel data in the client's format.
37
* zlibAfterBuf contains the zlib (deflated) encoding version.
38
* If the zlib compressed/encoded version is
39
* larger than the raw data or if it exceeds zlibAfterBufSize then
40
* raw encoding is used instead.
43
static int zlibBeforeBufSize = 0;
44
static char *zlibBeforeBuf = NULL;
46
static int zlibAfterBufSize = 0;
47
static char *zlibAfterBuf = NULL;
48
static int zlibAfterBufLen;
50
void rfbZlibCleanup(rfbScreenInfoPtr screen)
52
if (zlibBeforeBufSize) {
56
if (zlibAfterBufSize) {
64
* rfbSendOneRectEncodingZlib - send a given rectangle using one Zlib
69
rfbSendOneRectEncodingZlib(rfbClientPtr cl,
75
rfbFramebufferUpdateRectHeader rect;
80
char *fbptr = (cl->scaledScreen->frameBuffer + (cl->scaledScreen->paddedWidthInBytes * y)
81
+ (x * (cl->scaledScreen->bitsPerPixel / 8)));
86
maxRawSize = (cl->scaledScreen->width * cl->scaledScreen->height
87
* (cl->format.bitsPerPixel / 8));
89
if (zlibBeforeBufSize < maxRawSize) {
90
zlibBeforeBufSize = maxRawSize;
91
if (zlibBeforeBuf == NULL)
92
zlibBeforeBuf = (char *)malloc(zlibBeforeBufSize);
94
zlibBeforeBuf = (char *)realloc(zlibBeforeBuf, zlibBeforeBufSize);
97
/* zlib compression is not useful for very small data sets.
98
* So, we just send these raw without any compression.
100
if (( w * h * (cl->scaledScreen->bitsPerPixel / 8)) <
101
VNC_ENCODE_ZLIB_MIN_COMP_SIZE ) {
105
/* The translation function (used also by the in raw encoding)
106
* requires 4/2/1 byte alignment in the output buffer (which is
107
* updateBuf for the raw encoding) based on the bitsPerPixel of
108
* the viewer/client. This prevents SIGBUS errors on some
109
* architectures like SPARC, PARISC...
111
if (( cl->format.bitsPerPixel > 8 ) &&
112
( cl->ublen % ( cl->format.bitsPerPixel / 8 )) != 0 ) {
113
if (!rfbSendUpdateBuf(cl))
117
result = rfbSendRectEncodingRaw(cl, x, y, w, h);
124
* zlib requires output buffer to be slightly larger than the input
125
* buffer, in the worst case.
127
maxCompSize = maxRawSize + (( maxRawSize + 99 ) / 100 ) + 12;
129
if (zlibAfterBufSize < maxCompSize) {
130
zlibAfterBufSize = maxCompSize;
131
if (zlibAfterBuf == NULL)
132
zlibAfterBuf = (char *)malloc(zlibAfterBufSize);
134
zlibAfterBuf = (char *)realloc(zlibAfterBuf, zlibAfterBufSize);
139
* Convert pixel data to client format.
141
(*cl->translateFn)(cl->translateLookupTable, &cl->screen->serverFormat,
142
&cl->format, fbptr, zlibBeforeBuf,
143
cl->scaledScreen->paddedWidthInBytes, w, h);
145
cl->compStream.next_in = ( Bytef * )zlibBeforeBuf;
146
cl->compStream.avail_in = w * h * (cl->format.bitsPerPixel / 8);
147
cl->compStream.next_out = ( Bytef * )zlibAfterBuf;
148
cl->compStream.avail_out = maxCompSize;
149
cl->compStream.data_type = Z_BINARY;
151
/* Initialize the deflation state. */
152
if ( cl->compStreamInited == FALSE ) {
154
cl->compStream.total_in = 0;
155
cl->compStream.total_out = 0;
156
cl->compStream.zalloc = Z_NULL;
157
cl->compStream.zfree = Z_NULL;
158
cl->compStream.opaque = Z_NULL;
160
deflateInit2( &(cl->compStream),
161
cl->zlibCompressLevel,
165
Z_DEFAULT_STRATEGY );
166
/* deflateInit( &(cl->compStream), Z_BEST_COMPRESSION ); */
167
/* deflateInit( &(cl->compStream), Z_BEST_SPEED ); */
168
cl->compStreamInited = TRUE;
172
previousOut = cl->compStream.total_out;
174
/* Perform the compression here. */
175
deflateResult = deflate( &(cl->compStream), Z_SYNC_FLUSH );
177
/* Find the total size of the resulting compressed data. */
178
zlibAfterBufLen = cl->compStream.total_out - previousOut;
180
if ( deflateResult != Z_OK ) {
181
rfbErr("zlib deflation error: %s\n", cl->compStream.msg);
185
/* Note that it is not possible to switch zlib parameters based on
186
* the results of the compression pass. The reason is
187
* that we rely on the compressor and decompressor states being
188
* in sync. Compressing and then discarding the results would
189
* cause lose of synchronization.
193
rfbStatRecordEncodingSent(cl, rfbEncodingZlib, sz_rfbFramebufferUpdateRectHeader + sz_rfbZlibHeader + zlibAfterBufLen,
194
+ w * (cl->format.bitsPerPixel / 8) * h);
196
if (cl->ublen + sz_rfbFramebufferUpdateRectHeader + sz_rfbZlibHeader
199
if (!rfbSendUpdateBuf(cl))
203
rect.r.x = Swap16IfLE(x);
204
rect.r.y = Swap16IfLE(y);
205
rect.r.w = Swap16IfLE(w);
206
rect.r.h = Swap16IfLE(h);
207
rect.encoding = Swap32IfLE(rfbEncodingZlib);
209
memcpy(&cl->updateBuf[cl->ublen], (char *)&rect,
210
sz_rfbFramebufferUpdateRectHeader);
211
cl->ublen += sz_rfbFramebufferUpdateRectHeader;
213
hdr.nBytes = Swap32IfLE(zlibAfterBufLen);
215
memcpy(&cl->updateBuf[cl->ublen], (char *)&hdr, sz_rfbZlibHeader);
216
cl->ublen += sz_rfbZlibHeader;
218
for (i = 0; i < zlibAfterBufLen;) {
220
int bytesToCopy = UPDATE_BUF_SIZE - cl->ublen;
222
if (i + bytesToCopy > zlibAfterBufLen) {
223
bytesToCopy = zlibAfterBufLen - i;
226
memcpy(&cl->updateBuf[cl->ublen], &zlibAfterBuf[i], bytesToCopy);
228
cl->ublen += bytesToCopy;
231
if (cl->ublen == UPDATE_BUF_SIZE) {
232
if (!rfbSendUpdateBuf(cl))
243
* rfbSendRectEncodingZlib - send a given rectangle using one or more
244
* Zlib encoding rectangles.
248
rfbSendRectEncodingZlib(rfbClientPtr cl,
256
rfbRectangle partialRect;
263
/* Determine maximum pixel/scan lines allowed per rectangle. */
264
maxLines = ( ZLIB_MAX_SIZE(w) / w );
266
/* Initialize number of scan lines left to do. */
269
/* Loop until all work is done. */
270
while ( linesRemaining > 0 ) {
274
if ( maxLines < linesRemaining )
275
linesToComp = maxLines;
277
linesToComp = linesRemaining;
279
partialRect.h = linesToComp;
281
/* Encode (compress) and send the next rectangle. */
282
if ( ! rfbSendOneRectEncodingZlib( cl,
291
/* Technically, flushing the buffer here is not extrememly
292
* efficient. However, this improves the overall throughput
293
* of the system over very slow networks. By flushing
294
* the buffer with every maximum size zlib rectangle, we
295
* improve the pipelining usage of the server CPU, network,
296
* and viewer CPU components. Insuring that these components
297
* are working in parallel actually improves the performance
299
* Since, zlib is most useful for slow networks, this flush
300
* is appropriate for the desired behavior of the zlib encoding.
302
if (( cl->ublen > 0 ) &&
303
( linesToComp == maxLines )) {
304
if (!rfbSendUpdateBuf(cl)) {
310
/* Update remaining and incremental rectangle location. */
311
linesRemaining -= linesToComp;
312
partialRect.y += linesToComp;