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Add zlib encoding support (Alexander Graf)

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This patch adds zlib encoding support for VNC. It basically runs
the raw traffic through zlib, providing a pretty good compression
ratio.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6499 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-02-02 15:58:54 +00:00
parent d2a0102a4c
commit 059cef4092
1 changed files with 109 additions and 0 deletions
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109
vnc.c
View file

@ -29,6 +29,7 @@
#include "qemu_socket.h"
#include "qemu-timer.h"
#include "audio/audio.h"
#include <zlib.h>
#define VNC_REFRESH_INTERVAL (1000 / 30)
@ -144,6 +145,10 @@ struct VncState
size_t read_handler_expect;
/* input */
uint8_t modifiers_state[256];
Buffer zlib;
Buffer zlib_tmp;
z_stream zlib_stream[4];
};
static VncState *vnc_state; /* needed for info vnc */
@ -481,9 +486,108 @@ static void send_framebuffer_update_hextile(VncState *vs, int x, int y, int w, i
}
static void vnc_zlib_init(VncState *vs)
{
int i;
for (i=0; i<(sizeof(vs->zlib_stream) / sizeof(z_stream)); i++)
vs->zlib_stream[i].opaque = NULL;
}
static void vnc_zlib_start(VncState *vs)
{
buffer_reset(&vs->zlib);
// make the output buffer be the zlib buffer, so we can compress it later
vs->zlib_tmp = vs->output;
vs->output = vs->zlib;
}
static int vnc_zlib_stop(VncState *vs, int stream_id)
{
z_streamp zstream = &vs->zlib_stream[stream_id];
int previous_out;
// switch back to normal output/zlib buffers
vs->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 %d\n", stream_id);
VNC_DEBUG("VNC: opaque = %p | vs = %p\n", zstream->opaque, vs);
zstream->zalloc = Z_NULL;
zstream->zfree = Z_NULL;
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;
}
zstream->opaque = vs;
}
// XXX what to do if tight_compression changed in between?
// reserve memory in output buffer
buffer_reserve(&vs->output, vs->zlib.offset + 64);
// set pointers
zstream->next_in = vs->zlib.buffer;
zstream->avail_in = vs->zlib.offset;
zstream->next_out = vs->output.buffer + vs->output.offset;
zstream->avail_out = vs->output.capacity - vs->output.offset;
zstream->data_type = Z_BINARY;
previous_out = zstream->total_out;
// 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 zstream->total_out - previous_out;
}
static void send_framebuffer_update_zlib(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);
send_framebuffer_update_raw(vs, x, y, w, h);
bytes_written = vnc_zlib_stop(vs, 0);
if (bytes_written == -1)
return;
// 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;
}
static void send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
{
switch(vs->vnc_encoding) {
case VNC_ENCODING_ZLIB:
send_framebuffer_update_zlib(vs, x, y, w, h);
break;
case VNC_ENCODING_HEXTILE:
vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_HEXTILE);
send_framebuffer_update_hextile(vs, x, y, w, h);
@ -1169,6 +1273,7 @@ static void set_encodings(VncState *vs, int32_t *encodings, size_t n_encodings)
int i;
unsigned int enc = 0;
vnc_zlib_init(vs);
vs->features = 0;
vs->vnc_encoding = 0;
vs->tight_compression = 9;
@ -1189,6 +1294,10 @@ static void set_encodings(VncState *vs, int32_t *encodings, size_t n_encodings)
vs->features |= VNC_FEATURE_HEXTILE_MASK;
vs->vnc_encoding = enc;
break;
case VNC_ENCODING_ZLIB:
vs->features |= VNC_FEATURE_ZLIB_MASK;
vs->vnc_encoding = enc;
break;
case VNC_ENCODING_DESKTOPRESIZE:
vs->features |= VNC_FEATURE_RESIZE_MASK;
break;