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<html>
<head>
<title>VNC server for eCos</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<body bgcolor="#FFFFFF">
<h1>VNC server for eCos</h1>
<h2>Introduction</h2>
<p>VNC stands for Virtual Network Computing. It is in essence, a remote display
system which allows you to view a computing 'desktop' environment not only on
the machine where it is running, but from anywhere on the Internet and from
a wide variety of machine architectures. For full details of VNC, and to get
the vncviewer program see: <a href="http://www.uk.research.att.com/vnc/" target="VNC_PAGE">http://www.uk.research.att.com/vnc/</a>.
</p>
<p>The VNC server for eCos runs on the target platform and waits for a client
(vncviewer program running on a PC) to connect via an ethernet connection (port
5900). Once a client has connected, the target platform has a virtual screen,
keyboard and mouse.</p>
<p> </p>
<h2>Limitations</h2>
<p>The eCos port of the VNC server has been designed with some limitations in
order to keep memory and processor power requirements to a minimum.</p>
<ol>
<li>The VNC client must accept the settings that the VNC server suggests (bits-per-pixel,
number-of-colours and so on as specified at build time with the eCos configuration
tool) or the VNC server will just disconnect.</li>
<li>The VNC server only supports CoRRE encoding and RAW encoding for sending
display data to the client.</li>
<li>The VNC server does not support password authentication, the client is able
to connect without the user typing in a password.</li>
<li>Only one VNC client may connect to the VNC server at a time.</li>
</ol>
<p>In reality these limitations are not a problem.</p>
<p> </p>
<h2>VNC server API</h2>
<p>If the VNC server is to be used with the eCos port of MicroWindows, then VNC
server API may be ignored and the application should just use one of the API
supplied by MicroWindows.</p>
<h3>VNC server display API</h3>
<p>To use the VNC server display API the application should include the VNC server
header file by adding the following line to their C application:</p>
<p><font face="Courier New, Courier, mono"><font size="-1">#include <vnc-server.h>
/* VNC server header file *</font></font></p>
<p>This file specifies several function to manipulate the display.</p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><b>vnc_frame_forma</b></font><b><font face="Courier New, Courier, mono">t_t*
VncGetInfo(void)</font></b></font></p>
<p>The VNC get info function returns a pointer to a 'vnc_frame_format_t'
type structure and is used to get information about the VNC display. 'vnc_frame_format_t'
is defined in the vnc-server.h file as:</p>
<p><font face="Courier New, Courier, mono" size="-1">typedef struct<br>
{<br>
cyg_uint16 frame_width;<br>
cyg_uint16 frame_height;<br>
void * frame_buffer;<br>
bool rgb332;<br>
</font><font face="Courier New, Courier, mono" size="-1">bool
rgb555;<br>
bool rgb565;<br>
</font><font face="Courier New, Courier, mono" size="-1">bool
bgr233;<br>
} vnc_frame_format_t;</font></p>
<p>The frame_width and frame height fields contain the VNC server display
size in pixels.</p>
<p>The * frame_buffer pointer contains the address of the actual frame buffer
the VNC server uses, though the application should never write to this
buffer directly.</p>
<p>The final 4 (bool) fields specifiy the pixel format - only one of them
will be set to true.</p>
</td>
</tr>
</table>
<p> </p><table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b><font face="Courier New, Courier, mono">void
VncInit(vnc_colour_t colour)</font></b></font></p>
<p>The VNC initialise function, initialises the VNC server and paints the
display with the specified colour. This funcftion must be called before
any of the other VNC server display functions are used, except for VncGetInfo()
- which may be called at any time.</p>
<p>The type 'vnc_colour_t' is defined in the vnc-server.h file - and is
used to represent a colour. If the VNC server is built to support 8-bit
pixel data then 'vnc_colour_t' will be type cyg_uint8, but if 16-bit pixel
data is being used then 'vnc_colour_t' will be type cyg_uint16.</p>
</td>
</tr>
</table>
<p> </p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><b><font face="Courier New, Courier, mono">void
VncDrawPixel(cyg_uint16 x,<br>
cyg_uint16
y, <br>
vnc_colour_t colour)</font></b><font face="Courier New, Courier, mono"></font></font></p>
<p>The VNC draw pixel function simply draws a pixel of colour, 'colour',
at position ('x', 'y') on the VNC server display. Note that pixel (0,
0) is the top-left pixel in the display.</p>
</td>
</tr>
</table>
<p> </p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><b><font face="Courier New, Courier, mono">vnc_colour_t
VncReadPixel(cyg_uint16 x<br>
cyg_uint16 y)</font></b></font></p>
<p>The VNC read pixel function simply returns the colour of the pixel at
position ('x', 'y') on the VNC server display. Note that pixel (0, 0)
is the top-left pixel in the display.</p>
</td>
</tr>
</table>
<p> </p><table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b>void
VncDrawHorzLine(cyg_uint16 x1,<br>
cyg_uint16 x2, <br>
cyg_uint16 y, <br>
vnc_colour_t colour)</b></font></p>
<p>The VNC draw horizontal line function simply draws a line of pixels of
colour, 'colour', from position ('x1', 'y') to position ('x2', 'y') (inclusive)
on the VNC server display. Note that pixel (0, 0) is the top-left pixel
in the display.</p>
</td>
</tr>
</table>
<p> </p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b><font face="Courier New, Courier, mono">void
VncDrawVertLine(cyg_uint16 x,<br>
cyg_uint16 y1,<br>
cyg_uint16 y2, <br>
vnc_colour_t colour)</font></b></font></p>
<p>The VNC draw vertical line function simply draws a line of pixels of
colour, 'colour', from position ('x', 'y1') to position ('x', 'y2') (inclusive)
on the VNC server display. Note that pixel (0, 0) is the top-left pixel
in the display.</p>
</td>
</tr>
</table>
<p> </p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b><font face="Courier New, Courier, mono">void
VncFillRect(cyg_uint16 x1,<br>
cyg_uint16 y1,<br>
cyg_uint16 x2, <br>
cyg_uint16 y2, <br>
vnc_colour_t colour)</font></b></font></p>
<p>The VNC fill rectangle function draws a solid rectangle of colour, 'colour',
with top-left corner at ('x1', 'y1') and bottom right corner at ('x2',
'y2') (inclusive) on the VNC server display. Note that pixel (0, 0) is
the top-left pixel in the display.</p>
</td>
</tr>
</table>
<p> </p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b>void
VncCopyRect(cyg_uint16 x1,<br>
cyg_uint16 y1, <br>
cyg_uint16 width, <br>
cyg_uint16 height,<br>
cyg_uint16 x2,<br>
cyg_uint16 y2)</b></font></p>
<p>The VNC copy rectangle function copies a rectangle from one part of the
VNC display to another. The source rectangle is of width 'width', and
height 'height', with its top-left corner at ('x1', 'y1'). The destination
rectangle is the same size with its top-left corner at ('x2', 'y2'). Note
that pixel (0, 0) is the top-left pixel in the display.</p>
</td>
</tr>
</table>
<p> </p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b>void
VncCopyRect2Buffer(cyg_uint16 x,<br>
cyg_uint16 y,<br>
cyg_uint16 width,<br>
cyg_uint16 height,<br>
void *buffer,<br>
cyg_uint16 buff_w,<br>
cyg_uint16 buff_h,<br>
cyg_uint16 x_off,<br>
cyg_uint16 y_off)</b></font></p>
<p>The VNC copy rectangle to buffer function copies a rectangle of the VNC
server display to a buffer supplied by the application. This function
is useful for saving areas of the display which will need to be restored
later, such as the area under a mouse cursor.</p>
<p>The rectangle of the display to be copied is of width 'width' and height
'height' with its top-left corner at position ('x', 'y'). The address
of the buffer supplied to copy the image data is specified by '*buffer'.
This buffer is of width 'buff_w' and height 'buff_height'. If the buffer
width and height is larger than the rectangle being copied from the display,
an x and y offset may be supplied ('x_off' and 'y_off' respectively) to
offset where the rectangle of display data in the buffer.</p>
<p>For example a buffer of width = 50 and height = 40 could be defined with:</p>
<p><font face="Courier New, Courier, mono"><font size="-1">vnc_colour_t
my_buffer[40][50];</font></font></p>
<p>Then VncCopyRect2Buffer() could be called with:</p>
<p><font face="Courier New, Courier, mono"><font size="-1">VncCopyRect2Buffer(10,
/* x-pos on display */<br>
10,
/* y-pos on display */</font></font><br>
<font face="Courier New, Courier, mono"><font size="-1"> 30,
/* rectangle width on display */</font></font> <br>
<font face="Courier New, Courier, mono"><font size="-1"> 20,
/* rectangle heigth on display */</font></font> <br>
<font face="Courier New, Courier, mono"><font size="-1">(void
*)my_buffer, /* Address of buffer */<br>
</font><font face="Courier New, Courier, mono"><font size="-1"> 50,
/* buffer width */</font></font> <font size="-1"> <br>
</font><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><font size="-1"> 40,
/* buffer height */</font></font> <br>
</font></font><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><font size="-1"> 5,
/* buffer x-offset */</font></font> <font size="-1"> <br>
</font><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><font size="-1"> 6);
/* buffer y-offset */</font></font> <font size="-1"> </font></font><font size="-1">
<br>
</font></font></font></p>
<p>This would copy a 30 pixel wide, 20 pixel high rectangle from (10, 10)
of the VNC server display to the buffer 'my_buffer'. Inside the buffer
there would by an x-offset of 5 and a y offset of 6. Thus pixel (10, 10)
from the VNC server display would now be copied to my_buffer[6][5] - and
so on for the rest of the rectangle.</p>
</td>
</tr>
</table>
<p> </p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b>void
VncCopyBuffer2Rect(void *buffer,<br>
cyg_uint16 buff_w,<br>
cyg_uint16 buff_h, <br>
cyg_uint16 x_off,<br>
cyg_uint16 y_off,<br>
cyg_uint16 x, <br>
cyg_uint16 y,<br>
cyg_uint16 width,<br>
cyg_uint16 height)</b></font></p>
<p>The VNC copy buffer to rectangle function copies a rectangle from a buffer
supplied by the application to the VNC server display. This function is
usefull for restoring previously saved areas of the display.</p>
<p>For example, to restore the rectangle saved in the previous example use
of the VncCopyRect2Buffer() function above, the VncCopyBuff2Rect() would
be called with:</p>
<p><font face="Courier New, Courier, mono"><font size="-1">VncCopyBuffer2Rect(</font><font face="Courier New, Courier, mono"><font size="-1">(void
*)my_buffer, /* Address of buffer */</font></font><font size="-1"><br>
</font><font face="Courier New, Courier, mono"><font size="-1"> 50,
/* buffer width */</font></font> <font size="-1"> <br>
</font><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><font size="-1"> 40,
/* buffer height */</font></font> <br>
</font></font><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><font size="-1"> 5,
/* buffer x-offset */</font></font> <font size="-1"> <br>
</font><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"><font size="-1"> 6,
/* buffer y-offset */</font></font> <font size="-1"> </font></font><br>
</font></font><font face="Courier New, Courier, mono"><font size="-1"> 10,
/* x-pos on display */<br>
10,
/* y-pos on display */</font></font><br>
<font face="Courier New, Courier, mono"><font size="-1"> 30,
/* rectangle width on display */</font></font> <br>
<font face="Courier New, Courier, mono"><font size="-1"> 20);
/* rectangle heigth on display */</font></font> </p>
<p>Note that in most uses of the VncCopyBuff2Rect() and VncCopyRect2Buffer()
functions would be called with:<br>
width = buff_w<br>
heigth = buff_h<br>
x_off = 0<br>
y_off = 0.</p>
<p>In this case there is no offset into the buffer and the buffer is used
100% to store the rectangle from the display. <font face="Courier New, Courier, mono"><font size="-1">
</font></font></p>
</td>
</tr>
</table>
<p> </p><table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b>void
VncCopyBuffer2RectMask(void *buffer,<br>
cyg_uint16 buff_w,<br>
cyg_uint16 buff_h, <br>
cyg_uint16 x_off,<br>
cyg_uint16 y_off,<br>
cyg_uint16 x, <br>
cyg_uint16 y,<br>
cyg_uint16 width,<br>
cyg_uint16 height,<br>
<font face="Courier New, Courier, mono"> vnc_colour_t
mask_colour</font> )</b></font></p>
<p>The VNC copy buffer to rectangle with mask function works exactly like
VncCopyRect2Buffer(), except that a mask colour is also specified. Any
pixels in the buffer that have the value mask_colour, will not be copied
to the frame buffer - leaving the original pixels untouched.<font face="Courier New, Courier, mono"><font size="-1">
</font></font></p>
</td>
</tr>
</table>
<p> </p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><font face="Courier New, Courier, mono"></font><b>vnc_printf_return_t
VncPrintf(MWCFONT* font,<br>
</b></font><font face="Courier New, Courier, mono"><b> int
do_print,<br>
vnc_colour_t
colour,<br>
int
x,<br>
int
y,<br>
const
char *fmt, ... );)</b></font></p>
<p>The VNC printf function writes test to a specified position in the VNC
frame buffer, using the specified font and colour.</p>
<p>The '* font' argument is a pointer to a MWCFONT font structure. This
is the same font structure as used by MicroWindows, though the VNC server
has its own copy of the font description files. The available fonts are:</p>
<p> font_rom8x16<br>
font_rom8x8<br>
font_winFreeSansSerif11x13<br>
font_winFreeSystem14x16<br>
font_helvB10<br>
font_helvB12<br>
font_helvR10<br>
font_X5x7<br>
font_X6x13</p>
<p>If the font argument is set to '0', then the default font (winFreeSystem14x16)
is used.</p>
<p>The 'do_print' argument is used to specify whether the function should
actually write the text to the frame buffer. If do_print is non-zero,
then the text will be written to the frame buffer. If do_print is zero,
then no text will be written, but the return value from the function will
sill be valid.</p>
<p>The 'colour' argument specifies the colour to use to write the text.</p>
<p>The 'x' and 'y' arguments specify the pixel position (x, y) in the frame
buffer of the top left pixel of the first character to be printed.</p>
<p>The 'const char *fmt, ...' argumets are used as in a normal printf statement.</p>
<p>The function returns a data structure of type vnc_printf_return_t, this
is defined as:</p>
<p> typedef struct<br>
{<br>
int chars;<br>
cyg_uint16 width;<br>
cyg_uint16 height;<br>
} vnc_printf_return_t;</p>
<p>The 'chars' values is exactly as would have been returned by the printf()
function.</p>
<p>The width and height attributes specify the width and height of a rectangle
surrounding the text written to the screen. This data can be used to know
how much of the frame buffer needs to be painted to delete the text, or
(used together with the 'do_print' argument set to 0) to calculate how
much of the screen should be saved before printing to it so that it may
be restored later.</p>
<p>An example of writing some text to position (250, 200) of the frame buffer,
using the colout cyan and the font, winFreeSansSerif11x13:</p>
<p><font face="Courier New, Courier, mono"></font><font face="Courier New, Courier, mono"><font size="-1">vnc_printf_return_t
print_area;</font></font></p>
<p><font face="Courier New, Courier, mono"><font size="-1">print_area =
VncPrintf(&font_winFreeSansSerif11x13,<br>
1,<br>
</font><font face="Courier New, Courier, mono"><font size="-1"> </font></font><font size="-1">
VNC_CYAN, <br>
</font><font face="Courier New, Courier, mono"><font size="-1"> </font></font><font size="-1">
250,<br>
</font><font face="Courier New, Courier, mono"><font size="-1"> </font></font><font size="-1">
200,<br>
</font><font face="Courier New, Courier, mono"><font size="-1"> </font></font><font size="-1">
</font></font><font face="Courier New, Courier, mono"><font size="-1">"Hello
World!\nUsing winFreeSansSerif11x13 font");</font></font></p>
<p>Note: 'print_area.width' and 'print_area.height' will be set to indicate
how much of the frame buffer was used to print this text.</p>
<p>Another example, using the default font this time:</p>
<p><font face="Courier New, Courier, mono"><font size="-1">print_area =
VncPrintf(0,<br>
1,<br>
</font><font face="Courier New, Courier, mono"><font size="-1"> </font></font><font size="-1">VNC_BLACK,
<br>
</font><font face="Courier New, Courier, mono"><font size="-1"> </font></font><font size="-1">250,<br>
</font><font face="Courier New, Courier, mono"><font size="-1"> </font></font><font size="-1">200,<br>
</font><font face="Courier New, Courier, mono"><font size="-1"> </font></font></font><font face="Courier New, Courier, mono"><font size="-1">"50
* 34 = %d", 50*34);</font></font></p>
<p></p>
</td>
</tr>
</table>
<p>Also included in the vnc-server.h header file are 16 predefined colours:</p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td><font face="Courier New, Courier, mono"><b>VNC_BLACK<br>
VNC_BLUE<br>
VNC_GREEN<br>
VNC_CYAN<br>
VNC_RED<br>
VNC_MAGENTA<br>
VNC_BROWN<br>
VNC_LTGRAY<br>
VNC_LTGREY /* Same as VNC_LTGRAY */<br>
VNC_GRAY<br>
VNC_GREY /* Same as VNC_GRAY */<br>
VNC_LTBLUE<br>
VNC_LTGREEN<br>
VNC_LTCYAN<br>
VNC_LTRED<br>
VNC_LTMAGENTA<br>
VNC_YELLOW<br>
VNC_WHITE</b></font>
<p>These colours are all of type vnc_colour_t and are always correct for the selected
pixel type.</p>
</td>
</tr>
</table>
<p>Also contained in the vnc-server.h header file is a macro to convert from a
full RGB colour value to the nearest colour that the type vnc_colour_t can represent.
This macro is:</p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><b>VNC_RGB2COL(red, green, blue)</b></font></p>
<p>The arguments red, green and blue each have a value from 0 to 255.</p>
<p>For example, to initialise the VNC server display with a colour as close
to a very specific shade of green [red=156, green=229, blue=91] - the
VncInit() function could be called as follows:</p>
<p><font face="Courier New, Courier, mono" size="-1">VncInit( VNC_RGB2COL(156,
229, 91) );</font></p>
<p>Obviously the colour match will be better if the VNC server had been
built with 16 bits per pixel rather than with 8 bits per pixel, but in
each case the best available colour will be used.</p>
</td>
</tr>
</table>
<p>Though not strictly a display function, a function to sound a bell on the client
is available.</p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono"><b><font face="Courier New, Courier, mono">void
VncSoundBell(void)</font></b></font></p>
<p>The VNC Sound Bell function simply sounds a bell on the client - if the
client supports this.</p>
</td>
</tr>
</table>
<p> </p>
<h3>VNC server mouse API</h3>
<p>The VNC server mouse device driver is a standard eCos IO device driver. The
device name is "/dev/vnc_mouse" by default, but this may be modified
with the configuration tool. The first step in using the mouse device driver
is to use the cyg_io_lookup() function:</p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p> <font face="Courier New, Courier, mono" size="-1">Cyg_ErrNo mouse_err;<br>
cyg_io_handle_t mouse_handle;<br>
cyg_uint8 mouse_data[8];<br>
cyg_uint32 mouse_len;</font><br>
<br>
<font face="Courier New, Courier, mono" size="-1">mouse_err = cyg_io_lookup("/dev/vnc_mouse",
&mouse_handle); /* Open mouse device */ if (mouse_err == -ENOENT)<br>
{ <br>
diag_printf("Could not open mouse device\n");
<br>
} </font></p>
</td>
</tr>
</table>
<p>Once the cyg_io_lookup() function has found the mouse device driver, the driver
is active and should be read regularly to prevent the receive buffer from overflowing
with data. Data is read using the cyg_io_read() function:</p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono" size="-1">mouse_len = 8; /*
Try to read 8 bytes from mouse */ <br>
cyg_io_read(mouse_handle, mouse_data, &mouse_len ); <br>
if (mouse_len == 0)<br>
{<br>
diag_printf("Mouse has no new data\n");<br>
}<br>
else<br>
{ <br>
diag_printf("Have New mouse data:\n");</font><br>
<font face="Courier New, Courier, mono" size="-1"> <font face="Courier New, Courier, mono" size="-1">diag_printf(" Mouse
button data: 0x%x\n", mouse_data[1]);</font> </font> <br>
<font face="Courier New, Courier, mono" size="-1">diag_printf(" Mouse
x-coord: %d\n", mouse_data[2]*256 + mouse_data[3]);</font><br>
<font face="Courier New, Courier, mono" size="-1">diag_printf(" Mouse
y-coord: %d\n", mouse_data[4]*256 + mouse_data[5]);<br>
}</font> </p>
</td>
</tr>
</table>
<p>The cyg_io_read() function is a non-blocking function and each mouse event
generates 8 bytes of data:</p>
<p>Byte 0: Padding - always zero<br>
Byte 1: Button data (bit 0 = 1 if the left button is pressed, bit 2 = 1 if the
right button is pressed)<br>
Byte 2: Mose position x-coord MSB<br>
Byte 3: Mose position x-coord LSB<br>
Byte 4: Mose position y-coord MSB<br>
Byte 5: Mose position y-coord LSB<br>
Byte 6: Padding - always zero<br>
Byte 7: Padding - always zero </p>
<p> </p>
<h3>VNC server keyboard API</h3>
<p>The VNC server keyboard device driver is a standard eCos IO device driver.
The device name is "/dev/vnc_kbd" by default, but this may be modified
with the configuration tool. The first step in using the keyboard device driver
is to use the cyg_io_lookup() function:</p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p> <font face="Courier New, Courier, mono" size="-1">Cyg_ErrNo kdb_err;<br>
cyg_io_handle_t kbd_handle;<br>
cyg_uint8 kbd_data[8];<br>
cyg_uint32 kbd_len;</font><br>
<br>
<font face="Courier New, Courier, mono" size="-1">kbd_err = cyg_io_lookup("/dev/vnc_kbd",
&kbd_handle); /* Open kbd device */ <br>
if (kbd_err == -ENOENT)<br>
{ <br>
diag_printf("Could not open kbd device\n"); <br>
} </font></p>
</td>
</tr>
</table>
<p>Once the cyg_io_lookup() function has found the keyboard device driver, the
driver is active and should be read regularly to prevent the receive buffer
from overflowing with data. Data is read using the cyg_io_read() function:</p>
<table width="91%" border="1" cellspacing="0" cellpadding="0" bgcolor="#FFFFCC">
<tr>
<td>
<p><font face="Courier New, Courier, mono" size="-1">kbd_len = 4; /*
Try to read 4 bytes from keyboard */ <br>
cyg_io_read(kbd_handle, kbd_data, &kbd_len ); <br>
if (kbd_len == 0)<br>
{<br>
diag_printf("Keyboard has no new data\n");<br>
}<br>
else<br>
{ <br>
diag_printf("Have New keyboard data:\n");<br>
if (kbd_data[1])<br>
{ </font><br>
<font face="Courier New, Courier, mono" size="-1"><font face="Courier New, Courier, mono" size="-1"> diag_printf(" Keysym
value 0x%x pressed\n",<br>
kbd_data[2]*256
+ kbd_data[3]</font></font><font face="Courier New, Courier, mono" size="-1"><font face="Courier New, Courier, mono" size="-1">);<br>
}<br>
else<br>
{<br>
<font face="Courier New, Courier, mono" size="-1"> diag_printf(" Keysym
value 0x%x released\n",<br>
kbd_data[2]*256
+ kbd_data[3]</font></font><font face="Courier New, Courier, mono" size="-1"><font face="Courier New, Courier, mono" size="-1">);</font></font><font face="Courier New, Courier, mono" size="-1">
<br>
} </font></font><br>
<font face="Courier New, Courier, mono" size="-1">}</font> </p>
</td>
</tr>
</table>
<p>The cyg_io_read() function is a non-blocking function and each keystroke event
generates 4 bytes of data:</p>
<p>Byte 0: Padding - always zero<br>
Byte 1: Key pressed/released (1 when key pressed)<br>
Byte 2: Keysym value for key MSB<br>
Byte 3: Keysym value for key LSB<br>
</p>
<p>The actual key values are specified using the "keysym" values defined
by the X Window System. For most ordinary keys the keysym value is the same
as the corresponding ASCII value. For full details see either the Xlib Reference
Manual, published by O'Reilly & Associates or see the header file <X11/keysymdef.h>
from any X Window System installation (a google search for 'keysymdef.h' should
find it).</p>
<p> </p>
<h3> </h3>
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