From 059cef4092cc1f558f8f74cf2f762cef41237434 Mon Sep 17 00:00:00 2001 From: aliguori Date: Mon, 2 Feb 2009 15:58:54 +0000 Subject: [PATCH] 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 Signed-off-by: Anthony Liguori git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6499 c046a42c-6fe2-441c-8c8c-71466251a162 --- vnc.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 109 insertions(+) diff --git a/vnc.c b/vnc.c index f5235ab8f9..0c4d96e250 100644 --- a/vnc.c +++ b/vnc.c @@ -29,6 +29,7 @@ #include "qemu_socket.h" #include "qemu-timer.h" #include "audio/audio.h" +#include #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; -- 2.11.0