gwj / at91sam9263 · Commits

Commit 059cef4092cc1f558f8f74cf2f762cef41237434

Authored by aliguori
1 parent d2a0102a

Add zlib encoding support (Alexander Graf) 

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
Inline Side-by-side
Showing 1 changed file with 109 additions and 0 deletions
... ... @@ -29,6 +29,7 @@
29 29 #include "qemu_socket.h"
30 30 #include "qemu-timer.h"
31 31 #include "audio/audio.h"
  32 +#include <zlib.h>
32 33  
33 34 #define VNC_REFRESH_INTERVAL (1000 / 30)
34 35  
... ... @@ -144,6 +145,10 @@ struct VncState
144 145 size_t read_handler_expect;
145 146 /* input */
146 147 uint8_t modifiers_state[256];
  148 +
  149 + Buffer zlib;
  150 + Buffer zlib_tmp;
  151 + z_stream zlib_stream[4];
147 152 };
148 153  
149 154 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
481 486  
482 487 }
483 488  
  489 +static void vnc_zlib_init(VncState *vs)
  490 +{
  491 + int i;
  492 + for (i=0; i<(sizeof(vs->zlib_stream) / sizeof(z_stream)); i++)
  493 + vs->zlib_stream[i].opaque = NULL;
  494 +}
  495 +
  496 +static void vnc_zlib_start(VncState *vs)
  497 +{
  498 + buffer_reset(&vs->zlib);
  499 +
  500 + // make the output buffer be the zlib buffer, so we can compress it later
  501 + vs->zlib_tmp = vs->output;
  502 + vs->output = vs->zlib;
  503 +}
  504 +
  505 +static int vnc_zlib_stop(VncState *vs, int stream_id)
  506 +{
  507 + z_streamp zstream = &vs->zlib_stream[stream_id];
  508 + int previous_out;
  509 +
  510 + // switch back to normal output/zlib buffers
  511 + vs->zlib = vs->output;
  512 + vs->output = vs->zlib_tmp;
  513 +
  514 + // compress the zlib buffer
  515 +
  516 + // initialize the stream
  517 + // XXX need one stream per session
  518 + if (zstream->opaque != vs) {
  519 + int err;
  520 +
  521 + VNC_DEBUG("VNC: initializing zlib stream %d\n", stream_id);
  522 + VNC_DEBUG("VNC: opaque = %p | vs = %p\n", zstream->opaque, vs);
  523 + zstream->zalloc = Z_NULL;
  524 + zstream->zfree = Z_NULL;
  525 +
  526 + err = deflateInit2(zstream, vs->tight_compression, Z_DEFLATED, MAX_WBITS,
  527 + MAX_MEM_LEVEL, Z_DEFAULT_STRATEGY);
  528 +
  529 + if (err != Z_OK) {
  530 + fprintf(stderr, "VNC: error initializing zlib\n");
  531 + return -1;
  532 + }
  533 +
  534 + zstream->opaque = vs;
  535 + }
  536 +
  537 + // XXX what to do if tight_compression changed in between?
  538 +
  539 + // reserve memory in output buffer
  540 + buffer_reserve(&vs->output, vs->zlib.offset + 64);
  541 +
  542 + // set pointers
  543 + zstream->next_in = vs->zlib.buffer;
  544 + zstream->avail_in = vs->zlib.offset;
  545 + zstream->next_out = vs->output.buffer + vs->output.offset;
  546 + zstream->avail_out = vs->output.capacity - vs->output.offset;
  547 + zstream->data_type = Z_BINARY;
  548 + previous_out = zstream->total_out;
  549 +
  550 + // start encoding
  551 + if (deflate(zstream, Z_SYNC_FLUSH) != Z_OK) {
  552 + fprintf(stderr, "VNC: error during zlib compression\n");
  553 + return -1;
  554 + }
  555 +
  556 + vs->output.offset = vs->output.capacity - zstream->avail_out;
  557 + return zstream->total_out - previous_out;
  558 +}
  559 +
  560 +static void send_framebuffer_update_zlib(VncState *vs, int x, int y, int w, int h)
  561 +{
  562 + int old_offset, new_offset, bytes_written;
  563 +
  564 + vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_ZLIB);
  565 +
  566 + // remember where we put in the follow-up size
  567 + old_offset = vs->output.offset;
  568 + vnc_write_s32(vs, 0);
  569 +
  570 + // compress the stream
  571 + vnc_zlib_start(vs);
  572 + send_framebuffer_update_raw(vs, x, y, w, h);
  573 + bytes_written = vnc_zlib_stop(vs, 0);
  574 +
  575 + if (bytes_written == -1)
  576 + return;
  577 +
  578 + // hack in the size
  579 + new_offset = vs->output.offset;
  580 + vs->output.offset = old_offset;
  581 + vnc_write_u32(vs, bytes_written);
  582 + vs->output.offset = new_offset;
  583 +}
  584 +
484 585 static void send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
485 586 {
486 587 switch(vs->vnc_encoding) {
  588 + case VNC_ENCODING_ZLIB:
  589 + send_framebuffer_update_zlib(vs, x, y, w, h);
  590 + break;
487 591 case VNC_ENCODING_HEXTILE:
488 592 vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_HEXTILE);
489 593 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)
1169 1273 int i;
1170 1274 unsigned int enc = 0;
1171 1275  
  1276 + vnc_zlib_init(vs);
1172 1277 vs->features = 0;
1173 1278 vs->vnc_encoding = 0;
1174 1279 vs->tight_compression = 9;
... ... @@ -1189,6 +1294,10 @@ static void set_encodings(VncState *vs, int32_t *encodings, size_t n_encodings)
1189 1294 vs->features |= VNC_FEATURE_HEXTILE_MASK;
1190 1295 vs->vnc_encoding = enc;
1191 1296 break;
  1297 + case VNC_ENCODING_ZLIB:
  1298 + vs->features |= VNC_FEATURE_ZLIB_MASK;
  1299 + vs->vnc_encoding = enc;
  1300 + break;
1192 1301 case VNC_ENCODING_DESKTOPRESIZE:
1193 1302 vs->features |= VNC_FEATURE_RESIZE_MASK;
1194 1303 break;
... ...