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Atari ST series - Page 47

Atari ST series
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XBIOS Device and System Functions
Table 3-4. Data Block Pointed to by params
Byte
Offset
0
4*
6*
8*
10*
Label
topmode
1 buttons
2 xparam
3 yparam
xmax
ymax
xinitial
yinitial
Description
Specifies origin of y position
0 = y origin (0 point) at bottom
1 = y origin at top
The parameter for the IKBD set mouse buttons
command
In relative mode, x threshold
In absolute mode, x scale
In keycode mode, x delta
In relative mode, y threshold
In absolute mode, y scale
In keycode mode, y delta
Maximum x position of mouse
Maximum y position of mouse
Initial x position of mouse
Initial y position of mouse
Used only in mouse absolute mode.
The vector variable is used to pass the address of new
mouse packet interrupt handler. If you're changing the mouse
mode, chances are that the current handler will not work.
Both the MIDI and IKBD devices can send input to the
ST, as well as receive output. Receiving input is a little more
complex than sending output, however. Input from these de
vices is handled by a number of system interrupt routines
which store the characters received in buffers. Information
on the input buffers is provided in the section on the Iorec()
function, above. The XBIOS also provides a function called
Kbdvbase(), which returns pointers to several of the actual
interrupt routines that are used to handle the input func
tions. The syntax for this function is:
long vecbase;
vecbase = Kbdvbase();
where vecbase contains the address of a vector table. The
structure of this vector table is as follows:
Table 3-5. Vector Table Structure Pointed to by vecbase
Byte Vector
Offset Name Routine Called
0 midivec MIDI input routine
4 vkbderr IKBD ACIA overrun error routine
8 vmiderr MIDI ACIA overrun error routine
{ '
39

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