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VMS DECwindows Device Driver Manual
A.2 Input Buffer Control Block (INB)
The input buffer control block (INB) in the I/O database defines the
control block for the input queue buffer. INB provides control of the
server/driver interface and pointers to the input queue and free
packets (see Figure A-2). Table A-2 lists and defines the fields
of the INB.
One ACB (AST control block) is required for each input queue. An ACB is
allocated at offset INB$B_ACB within the INB structure. It is defined
by $ACBDEF and the 28-byte length is specified by ACB$K_LENGTH. The INB
is defined in module $DECWCOMMON and the length is specified by
constant INB$K_LENGTH.
Figure A-2 Input Buffer Control Block (INB)
4735INBSTRUCT.TEX
Table A-2 Input Buffer Control Block Fields
| Field Name |
Contents |
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INB$L_INPUT_QUEUE_FLINK
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The forward link to the first or next input packet structure (INP) in
the input queue.
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INB$L_INPUT_QUEUE_BLINK
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The backward link to the last or previous input packet structure (INP)
in the input queue.
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INB$W_SIZE
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Total size in bytes of the input buffer.
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INB$B_TYPE
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Defines the system or major type of data structure (DECwindows) that is
read by the System Dump Analyzer (SDA). The common driver writes the
symbolic constant DYN$C_DECW in this field when the common driver
creates the INB.
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INB$B_SUB_TYPE
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Defines the specific (subtype) data structure (INB) within the major
type that is read by the SDA. When the common driver creates the INB,
the common driver writes the symbolic constant DYN$C_DECW_INB in this
field.
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INB$L_VSYNC_UCB
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The pointer to the output UCB whose driver first reported a vertical
synchronization (VSYNC) interval.
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INB$L_FREE_QUEUE_FLINK
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The forward link to the next packet in the free queue.
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INB$L_FREE_QUEUE_BLINK
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The backward link to the previous packet in the free queue.
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INB$L_NOHISTORY_FLINK
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Reserved.
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INB$L_NOHISTORY_BLINK
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Reserved.
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INB$L_HISTORY_BUFFER
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A pointer to the motion history buffer (MHB).
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INB$L_HISTORY_SIZE
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The current size in pages of the motion history buffer.
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INB$L_FLAGS
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A 32-bit field containing interface status bits. Mask bits in this
field correspond to five possible states:
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INB$V_ACB_BUSY
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Bit 0, AST control block already queued.
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INB$V_AWAKE
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Bit 1, AST not required for server.
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INB$V_SERVER_TIMED
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Bit 2, if set, check server (AST-inhibit) timer for zero before sending
AST.
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INB$V_NON_INT_BOX
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Bit 3, if set, motion event data is inhibited when pointer is in the
noninterest box.
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INB$V_MHB_BUSY
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Bit 4, if set, the motion history buffer is busy with the server or is
disabled by the server. A value of 0 enables the buffer.
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INB$B_ACB
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A pointer to the AST control block 28-byte array.
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INB$L_SAVED_PID
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The process ID of the device that sent the AST. EXE$QIO obtains the
process identification from the PCB and writes the value into this
field.
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INB$W_NON_INT_BOX_X1
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Address of the first
x-axis pointer events noninterest box.
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INB$W_NON_INT_BOX_Y1
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Address of the first
y-axis pointer events noninterest box.
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INB$W_NON_INT_BOX_X2
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Address of the second
x-axis pointer events noninterest box.
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INB$W_NON_INT_BOX_Y2
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Address of the second
y-axis pointer events noninterest box.
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INB$B_SAVED_RMOD
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The access mode value of the process at the time of the I/O request.
EXE$QIO obtains the process access mode from the PSL and writes the
value into this field.
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INB$W_VERSION
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The INB version number.
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INB$L_TIMESTAMP_MONTH
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The timestamp with month.
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INB$L_TIMESTAMP_MS
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Timestamp to the nearest millisecond.
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INB$L_SCHED_QUANTUM
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Event time slice in server schedule.
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INB$W_SCHED_FLAGS
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A 16-bit field containing interface status bits concerning event
scheduling in the server. Mask bits in this field correspond to three
possible states:
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INB$V_INPUT_PENDING
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Bit 0, packet in queue if set.
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INB$V_QUANTUM_EXPIRED
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Bit 1, time slot expired if set.
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INB$V_SCHED_YIELD
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Bit 2, yield to a higher priority event if set.
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INB$L_COUNTER1
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Reserved.
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INB$L_COUNTER2
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Reserved.
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INB$L_COUNTER3
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Reserved.
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INB$L_COUNTER4
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Reserved.
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INB$L_PFN_COUNT
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A pointer to the page frame counter indicating the page frame numbers
(PFNs) for the shared buffer.
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INB$L_PFN_LIST
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A pointer to the page frame number list.
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1read only fields
A.3 Input Packet (INP)
The input packet (INP) data structure defines the packet format used in
the interface between the common device driver and the DECwindows
server. The basic DECwindows format of the input packet conforms with
the X event format in the X Window System protocol.
Some fields in the packets of certain events may vary. The packet
illustrated in Figure A-3 is a typical input event generated by a
pointing device or keyboard. Input events include key, button, and
pointer motion events. The first 12 bytes (3 longwords) are common to
all events. The event information is always 32 bytes, excluding the
prefixed forward/ backward pointers (FLINK/BLINK) for VMS.
Table A-3 defines the fields of the packet.
Figure A-3 Input Packet Data Structure (INP)
4735INPSTRUCT.TEX
Table A-3 Input Packet Fields
| Field Name |
Contents |
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INP$L_FLINK
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The forward link to the next INP structure. This field is filled in by
the class driver queue routines.
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INP$L_BLINK
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The backward link to the previous INP structure. This field is filled
in by the class driver queue routines.
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INP$B_TYPE
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Specifies the X11 event type. The class driver writes the packet type
in this field when it creates the INP. Possible key definition states:
KEYPRESS, KEYRELEASE. Possible mouse definition states: BUTTONPRESS,
BUTTONRELEASE, and MOTIONNOTIFY.
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INP$B_DETAIL
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A keyboard or mouse code specifying the key or button activity.
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INP$W_SEQUENCE
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The packet sequence number in the transmission session.
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INP$L_TIMESTAMP
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The date/time of packet creation.
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INP$L_ROOT_WIN
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The pointer to a root window data structure in the display application.
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INP$L_EVENT_WIN
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The pointer to the event window data structure in the application where
the current activity is referenced.
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INP$L_CHILD_WIN
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The pointer to a child display window in the application associated
with the current activity. (The parent is the event window data
structure.)
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INP$W_ROOT_X
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A value in pixels specifying the horizontal placement of the upper left
corner of the root window on the screen.
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INP$W_ROOT_Y
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A value in pixels specifying the vertical placement of the upper left
corner of the root window on the screen.
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INP$W_EVENT_X
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A value in pixels specifying the pointer movement (left, right,
distance) along the
x-axis.
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INP$W_EVENT_Y
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A value in pixels specifying the pointer movement (up, down, distance)
along the
y-axis.
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INP$W_KEY_BUTTON_MASK
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A 16-bit mask marking the bit position that defines a specific function
for a key or button. The following bits in this field identify specific
functions of the input event:
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INP$V_SHIFTMASK
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Bit 0, shift key pressed.
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INP$V_CAPSLOCKMASK
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Bit 1, caps lock key pressed.
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INP$V_CONTROLMASK
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Bit 2, control key pressed.
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INP$V_MOD1MASK
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Bit 3, the key pressed is modifying MB1.
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INP$V_MOD2MASK
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Bit 4, the key pressed is modifying MB2.
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INP$V_MOD3MASK
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Bit 5, the key pressed is modifying MB3.
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INP$V_MOD4MASK
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Bit 6, the key pressed is modifying MB4.
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INP$V_MOD5MASK
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Bit 7, the key pressed is modifying MB5.
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INP$V_BUTTON1MASK
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Bit 8, MB1 is pressed.
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INP$V_BUTTON2MASK
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Bit 9, MB2 is pressed.
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INP$V_BUTTON3MASK
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Bit 10, MB3 is pressed.
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INP$V_BUTTON4MASK
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Bit 11, MB4 is pressed.
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INP$V_BUTTON5MASK
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Bit 12, MB5 is pressed.
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INP$V_UNUSED1MASK
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Bit 13, reserved.
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INP$V_UNUSED2MASK
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Bit 14, reserved.
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INP$V_ANYMODIFIER
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Bit 15, set when any grab button or grab key modifier is pressed.
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1read only fields
A.4 Keyboard Information Block (KIB)
The keyboard information block (KIB) in the I/O database contains
keyboard characteristics that are used in the execution of the keyboard
information $QIO system service. During the keyboard information sense
or set mode $QIO call, data is passed between server and driver by the
system service reading or writing the KIB. The p2 $QIO
parameter points to the starting address of the block. The fields
define bell and keyclick volume and autorepeat information (see
Figure A-4). Table A-4 lists and defines the fields of the KIB.
The length of the data structure is defined by the constant
KIB$S_KBD_INFO.
Figure A-4 Keyboard Information Block
4735KIBSTRUCT.TEX
Table A-4 Keyboard Information Block Fields
| Field Name |
Contents |
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KIB$L_ENABLE_MASK
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Entry to the 256-bit autorepeat enable mask for the LK201 keys. The
mask defines which keys are in autorepeat mode. The bits are numbered 0
to 255 and each bit position corresponds to a specific key position on
an LK201 keyboard. For example, using decimal keycode numbering,
mask-bit 90 corresponds to the 90 key position (F5) on the LK201
keyboard.
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KIB$L_KEYCLICK_VOL
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A longword specifying the keyclick volume in percent. A value of 100
specifies the loudest click while a value 0 turns the keyclick off. A
value of --1 provides a default volume of 70 percent.
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KIB$L_BELL_VOL
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A longword specifying the bell volume in percent. A value of 100
specifies the loudest ring while a value 0 turns the bell off. A value
of --1 provides a default volume of 70 percent.
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KIB$L_AUTO_ON_OFF
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Defines the state of the autorepeat feature. A value of 0 turns
autorepeat on and a value of 1 turns it off.
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1read only fields
A.5 Motion History Buffer (MHB)
The motion history buffer (MHB) data structure in the I/O database
provides a storage area for pointing device movements as history
events. The buffer structure contains a 16-byte control block or header
at the top followed by (starting at address 1610) 8-byte
motion history packets (MHPs) that make up a ring buffer. Each history
packet contains x-axis and y-axis movement with an
event timestamp (see Figure A-5). Table A-5 lists and defines
the fields of the motion history buffer.
The MHB header and MHP packets are defined by the $DECWCOMMON macro.
The MHB header length is defined by constant MHB$S_MHB_STRUCT and the
MHP packet length (8 bytes) is defined by MHP$K_LENGTH. Field
MHB$L_PUT_PTR points to the next free packet and field MHB$L_GET_PTR
points to the oldest pointer motion event. Field MHB$L_END_PTR points
to the last byte in the buffer. MHB$T_RING points to the starting
address of the ring buffer packet area or the first packet in the ring.
Figure A-5 Motion History Buffer Data Structure
4735MHBSTRUCT.TEX
Table A-5 Motion History Buffer Fields
| Field Name |
Contents |
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MHB$L_PUT_PTR
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Points to the next or oldest free packet in the ring.
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MHB$L_GET_PTR
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Points to the oldest motion event packet in the ring.
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MHB$W_SIZE
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Size in bytes of the history buffer.
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MHB$B_TYPE
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Defines the system or major type of data structure (DECwindows) that is
read by the System Dump Analyzer (SDA). The common driver writes the
symbolic constant DYN$C_DECW in this field when the common driver
creates the MHB.
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MHB$B_SUBTYPE
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Defines the specific (subtype) data structure (MHB) within the major
type that is read by the SDA. When the common driver creates the MHB,
the common driver writes the symbolic constant DYN$C_DECW_MHB in this
field.
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MHB$L_END_PTR
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Points to the last free packet in the ring.
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MHP$W_EVENT_X
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A packet event value in pixels specifying the pointer movement (left,
right, distance) along the
x-axis.
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MHP$W_EVENT_Y
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A packet event value in pixels specifying the pointer movement (up,
down, distance) along the
y-axis.
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MHP$L_TIMESTAMP
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A packet event value specifying the date/time of the pointer movement.
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1read only fields
A.6 Unit Control Block for Input Device
A unit control block (UCB) data structure is a variable-length block in
the I/O database that describes the characteristics of a single device
unit. The driver-loading procedure creates some static fields. The
operating system and device drivers can read and modify all nonstatic
fields of the UCB.
The general UCB structure for an input device with a port/class
interface is shown in Figure A-6. It contains five sections: the
system section (base UCB), the class driver terminal section, the
DECwindows input device extension, the port driver terminal section,
and the port extension region.
The system section of the terminal driver UCB contains the fields of
the UCB that are present in all of the UCBs on the system. The length
of the system UCB is defined by UCB$K_LENGTH.
The class driver terminal section of the UCB contains fields that are
needed by the class driver. These fields have names of the form
UCB$x_TT_fieldname, where x denotes the
field size and fieldname is the name of the field. The
UCB$K_TT_LENGTH constant defines the length of the class driver section
of the UCB.
The DECwindows input extension section contains fields that are needed
by all DECwindows device drivers for communication and processing.
These fields have names of the form DWI$x_fieldname,
where x denotes the field size and fieldname is the
name of the field. Symbol UCB$L_DECW_I_DWI is always the address of the
input extension starting address.
The port driver terminal section of the UCB contains fields that both
the class and port driver must access. These fields have names of the
form UCB$x_TP_fieldname, where x denotes the
field size and fieldname is the name of the field. Although a
port driver may not actually use all these fields, they are needed by
other software.
The terminal port extension region is defined by the terminal port
driver. It can be any length and contain any context that the port
driver needs in order to execute the port functions.
Figure A-6 Unit Control Block General Structure
A.6.1 UCB/DECwindows Common Input Extension (DWI)
Each terminal device on the system has its own UCB, including VMS
terminal extensions for port and class drivers (described in the
OpenVMS VAX Device Support Reference Manual). A DECwindows UCB includes a common input extension
(DWI/DECW) and a device-specific extension (see Figure A-6). UCB
class driver section field UCB$L_DECW_I_DWI points to the DWI extension
starting address. Note that field UCB$L_TT_WFLINK is overwritten and
redefined as UCB$L_DECW_I_DWI when the DECwindows extension is created
by macro $DECWINPUTUCB (invoked by $DECWGBL). The common DWI extension
length is specified at B816 (18410) by
DWI$K_DECW_COMMON_LENGTH.
This section describes the DWI common input extension structure (see
Figure A-7). Table A-6 lists and defines the fields of the
DECwindows UCB common input extension.
Figure A-7 UCB/DECwindows Common Input Extension
4735DWISTRUCT.TEX
Table A-6 UCB/DECwindows Common Input Extension Fields
| Field Name |
Contents |
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DWI$L_DECW_INB
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Pointer to the INB header.
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DWI$L_DECW_OUTPUT_UCB
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Pointer to the start of the output UCB.
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DWI$L_DECW_DEV_CHARS
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Pointer to the DVI.
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DWI$L_DECW_PRIVATE
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Defines the escape point for extensions (reserved for Digital).
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DWI$L_DECW_SILO
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Pointer to the start of the SILO
1 block.
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DWI$T_DECW_SILO
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The SILO buffer area (block) defined by the $SILODEF macro.
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DWI$B_DECW_DEV_TYPE
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A byte that defines the input device type (mouse/keyboard).
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DWI$L_DECW_INIT_VECTOR
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Offset to the initialization routine that starts the device self-test.
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DWI$L_DECW_FUNC_VECTOR
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Offset to the powerfail function routine.
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DWI$L_DECW_UART
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Address of the UART/CSR
2 for the serial input device.
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1SILO is a software version of a Service In Logical Order
buffer for serial input and output data in the channel associated with
the UCB.
2UART is a universal asynchronous receiver/transmitter chip
for serial interfaces and CSR is the Control/Status Register.
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