X Synchronization Extension Protocol
X Consortium Standard
Tim Glauert
Olivetti Research
MultiWorks
Dave Carver
Digital Equipment Corporation
MIT/Project Athena
Jim Gettys
Digital Equipment Corporation
Cambridge Research Laboratory
David P. Wiggins
X Consortium, Inc.
James Jones
NVIDIA Corporation
X Version 11, Release 7.7
Version 3.1
Copyright © 1991 Olivetti Research Limited, Cambridge England, Digital
Equipment Corporation, Maynard, Massachusetts, X Consortium
Copyright © 2010 NVIDIA Corporation
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notice appear in all copies. Olivetti, Digital, MIT, the X Consortium, and
NVIDIA make no representations about the suitability for any purpose of the
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Table of Contents
1. Synchronization Protocol
Description
Types
Errors
Requests
Events
2. Encoding
Encoding New Types
Encoding Errors
Encoding Requests
Encoding Events
Chapter 1. Synchronization Protocol
Table of Contents
Description
Types
Errors
Requests
Events
The core X protocol makes no guarantees about the relative order of execution
of requests for different clients. This means that any synchronization between
clients must be done at the client level in an operating system-dependent and
network-dependent manner. Even if there was an accepted standard for such
synchronization, the use of a network introduces unpredictable delays between
the synchronization of the clients and the delivery of the resulting requests
to the X server.
The core X protocol also makes no guarantees about the time at which requests
are executed, which means that all clients with real-time constraints must
implement their timing on the host computer. Any such timings are subject to
error introduced by delays within the operating system and network and are
inefficient because of the need for round-trip requests that keep the client
and server synchronized.
The synchronization extension provides primitives that allow synchronization
between clients to take place entirely within the X server. This removes any
error introduced by the network and makes it possible to synchronize clients on
different hosts running different operating systems. This is important for
multimedia applications, where audio, video, and graphics data streams are
being synchronized. The extension also provides internal timers within the X
server to which client requests can be synchronized. This allows simple
animation applications to be implemented without any round-trip requests and
makes best use of buffering within the client, network, and server.
Description
The mechanism used by this extension for synchronization within the X server is
to block the processing of requests from a client until a specific
synchronization condition occurs. When the condition occurs, the client is
released and processing of requests continues. Multiple clients may block on
the same condition to give inter-client synchronization. Alternatively, a
single client may block on a condition such as an animation frame marker.
The extension adds Counter, Alarm, and Fence to the set of resources managed by
the server. A counter has a 64-bit integer value that may be increased or
decreased by client requests or by the server internally. A client can block by
sending an Await request that waits until one of a set of synchronization
conditions, called TRIGGERs, becomes TRUE. Alarms generate events when counter
values go through a specified transition. A fence has two possible states:
triggered and not triggered. Client requests can put the fence in either of
these states. A client can block until one of a set of fences becomes triggered
by sending an AwaitFence request. Fences are bound to a particular screen at
creation time.
The CreateCounter request allows a client to create a Counter that can be
changed by explicit SetCounter and ChangeCounter requests. These can be used to
implement synchronization between different clients.
There are some counters, called System Counters, that are changed by the server
internally rather than by client requests. The effect of any change to a system
counter is not visible until the server has finished processing the current
request. In other words, system counters are apparently updated in the gaps
between the execution of requests rather than during the actual execution of a
request. The extension provides a system counter that advances with the server
time as defined by the core protocol, and it may also provide counters that
advance with the real-world time or that change each time the CRT screen is
refreshed. Other extensions may provide their own extension-specific system
counters.
The extension provides an Alarm mechanism that allows clients to receive an
event on a regular basis when a particular counter is changed.
The CreateFence request allows a client to create a Fence that can be triggered
and reset using TriggerFence and ResetFence requests, respectively. CreateFence
takes a drawable argument that implies which screen the fence should be created
on. The TriggerFence request changes the fence's state only after all previous
rendering commands affecting objects owned by the given fence's screen have
completed. Note that while fence objects are bound to a screen and the simple
trigger operation provided by this extension operates at screen granularity,
other extensions may add more fine-grained trigger operations based on any
number of events. The screen binding merely establishes an upper bound for the
scope of fence operations.
Types
Please refer to the X11 Protocol specification as this document uses syntactic
conventions established there and references types defined there.
The following new types are used by the extension.
INT64: 64-bit signed integer
COUNTER: XID
VALUETYPE: {Absolute,Relative};
TESTTYPE: {PositiveTransition,NegativeTransition,
PositiveComparison,NegativeComparison}
TRIGGER: [
counter:COUNTER,
value-type:VALUETYPE,
wait-value:INT64,
test-type:TESTTYPE
]
WAITCONDITION: [
trigger:TRIGGER,
event-threshold:INT64
]
SYSTEMCOUNTER: [
name:STRING8,
counter:COUNTER,
resolution:INT64
]
ALARM: XID
ALARMSTATE: {Active,Inactive,Destroyed}
FENCE: XID
The COUNTER type defines the client-side handle on a server Counter. The value
of a counter is an INT64.
The TRIGGER type defines a test on a counter that is either TRUE or FALSE. The
value of the test is determined by the combination of a test value, the value
of the counter, and the specified test-type.
The test value for a trigger is calculated using the value-type and wait-value
fields when the trigger is initialized. If the value-type field is not one of
the named VALUETYPE constants, the request that initialized the trigger will
return a Value error. If the value-type field is Absolute, the test value is
given by the wait-value field. If the value-type field is Relative, the test
value is obtained by adding the wait-value field to the value of the counter.
If the resulting test value would lie outside the range for an INT64, the
request that initialized the trigger will return a Value error. If counter is
None and the value-type is Relative, the request that initialized the trigger
will return a Match error. If counter is not None and does not name a valid
counter, a Counter error is generated.
If the test-type is PositiveTransition, the trigger is initialized to FALSE,
and it will become TRUE when the counter changes from a value less than the
test value to a value greater than or equal to the test value. If the test-type
is NegativeTransition, the trigger is initialize to FALSE, and it will become
TRUE when the counter changes from a value greater than the test value to a
value less than or equal to the test value. If the test-type is
PositiveComparison, the trigger is TRUE if the counter is greater than or equal
to the test value and FALSE otherwise. If the test-type is NegativeComparison,
the trigger is TRUE if the counter is less than or equal to the test value and
FALSE otherwise. If the test-type is not one of the named TESTTYPE constants,
the request that initialized the trigger will return a Value error. A trigger
with a counter value of None and a valid test-type is always TRUE.
The WAITCONDITION type is simply a trigger with an associated event-threshold.
The event threshold is used by the Await request to decide whether or not to
generate an event to the client after the trigger has become TRUE. By setting
the event-threshold to an appropriate value, it is possible to detect the
situation where an Await request was processed after the TRIGGER became TRUE,
which usually indicates that the server is not processing requests as fast as
the client expects.
The SYSTEMCOUNTER type provides the client with information about a
SystemCounter. The name field is the textual name of the counter that
identifies the counter to the client. The counter field is the client-side
handle that should be used in requests that require a counter. The resolution
field gives the approximate step size of the system counter. This is a hint to
the client that the extension may not be able to resolve two wait conditions
with test values that differ by less than this step size. A microsecond clock,
for example, may advance in steps of 64 microseconds, so a counter based on
this clock would have a resolution of 64.
The only system counter that is guaranteed to be present is called SERVERTIME,
which counts milliseconds from some arbitrary starting point. The least
significant 32 bits of this counter track the value of Time used by the server
in Events and Requests. Other system counters may be provided by different
implementations of the extension. The X Consortium will maintain a registry of
system counter names to avoid collisions in the name space.
An ALARM is the client-side handle on an Alarm resource.
The FENCE type defines the client-side handle on a server Fence. A fence can
only be in one of two states, represented by a BOOL. If the value is TRUE, the
fence is in the triggered state. Otherwise, the fence is in the not triggered
state.
Errors
Counter This error is generated if the value for a COUNTER argument in a
request does not name a defined COUNTER.
Alarm This error is generated if the value for an ALARM argument in a request
does not name a defined ALARM.
Fence This error is generated if the value for a FENCE argument in a request
does not name a defined FENCE.
Requests
version-major,version-minor: CARD8
=>
version-major,version-minor: CARD8
This request must be executed before any other requests for
this extension. If a client violates this rule, the results
of all SYNC requests that it issues are undefined. The
request takes the version number of the extension that the
client wishes to use and returns the actual version number
being implemented by the extension for this client. The
extension may return different version numbers to a client
Initialize depending of the version number supplied by that client.
This request should be executed only once for each client
connection.
Given two different versions of the SYNC protocol, v1 and
v2, v1 is compatible with v2 if and only if v1.version_major
= v2.version_major and v1.version_minor <= v2.version_minor.
Compatible means that the functionality is fully supported
in an identical fashion in the two versions.
This document describes major version 3, minor version 1 of
the SYNC protocol.
=>
system-counters: LISTofSYSTEMCOUNTER
Errors: Alloc
ListSystemCounters This request returns a list of all the system counters that
are available at the time the request is executed, which
includes the system counters that are maintained by other
extensions. The list returned by this request may change as
counters are created and destroyed by other extensions.
id: COUNTER
initial-value: INT64
Errors: IDChoice,Alloc
CreateCounter
This request creates a counter and assigns the specified id
to it. The counter value is initialized to the specified
initial-value and there are no clients waiting on the
counter.
counter: COUNTER
Errors: Counter,Access
This request destroys the given counter and sets the counter
fields for all triggers that specify this counter to None.
All clients waiting on the counter are released and a
CounterNotify event with the destroyed field set to TRUE is
DestroyCounter sent to each waiting client, regardless of the
event-threshold. All alarms specifying the counter become
Inactive and an AlarmNotify event with a state field of
Inactive is generated. A counter is destroyed automatically
when the connection to the creating client is closed down if
the close-down mode is Destroy. An Access error is generated
if counter is a system counter. A Counter error is generated
if counter does not name a valid counter.
counter: COUNTER
=>
value: INT64
QueryCounter Errors: Counter
This request returns the current value of the given counter
or a generates Counter error if counter does not name a
valid counter.
wait-list: LISTofWAITCONDITION
Errors: Counter,Alloc,Value
When this request is executed, the triggers in the wait-list
are initialized using the wait-value and value-type fields,
as described in the definition of TRIGGER above. The
processing of further requests for the client is blocked
until one or more of the triggers becomes TRUE. This may
happen immediately, as a result of the initialization, or at
some later time, as a result of a subsequent SetCounter,
ChangeCounter or DestroyCounter request.
A Value error is generated if wait-list is empty.
When the client becomes unblocked, each trigger is checked
to determine whether a CounterNotify event should be
generated. The difference between the counter and the test
Await value is calculated by subtracting the test value from the
value of the counter. If the test-type is PositiveTransition
or PositiveComparison, a CounterNotify event is generated if
the difference is at least event-threshold. If the test-type
is NegativeTransition or NegativeComparison, a CounterNotify
event is generated if the difference is at most
event-threshold. If the difference lies outside the range
for an INT64, an event is not generated.
This threshold check is made for each trigger in the list
and a CounterNotify event is generated for every trigger for
which the check succeeds. The check for CounterNotify events
is performed even if one of the triggers is TRUE when the
request is first executed. Note that a CounterNotify event
may be generated for a trigger that is FALSE if there are
multiple triggers in the request. A CounterNotify event with
the destroyed flag set to TRUE is always generated if the
counter for one of the triggers is destroyed.
counter: COUNTER
amount: INT64
Errors: Counter,Access,Value
This request changes the given counter by adding amount to
the current counter value. If the change to this counter
satisfies a trigger for which a client is waiting, that
client is unblocked and one or more CounterNotify events may
be generated. If the change to the counter satisfies the
ChangeCounter trigger for an alarm, an AlarmNotify event is generated and
the alarm is updated. An Access error is generated if
counter is a system counter. A Counter error is generated if
counter does not name a valid counter. If the resulting
value for the counter would be outside the range for an
INT64, a Value error is generated and the counter is not
changed.
It should be noted that all the clients whose triggers are
satisfied by this change are unblocked, so this request
cannot be used to implement mutual exclusion.
counter: COUNTER
value: INT64
Errors: Counter,Access
SetCounter This request sets the value of the given counter to value.
The effect is equivalent to executing the appropriate
ChangeCounter request to change the counter value to value.
An Access error is generated if counter names a system
counter. A Counter error is generated if counter does not
name a valid counter.
id: ALARM
values-mask: CARD32
values-list: LISTofVALUE
left">Errors: IDChoice,Counter,Match,Value,Alloc
This request creates an alarm and assigns the identifier id
to it. The values-mask and values-list specify the
attributes that are to be explicitly initialized. The
attributes for an Alarm and their defaults are:
Attribute Type Default
trigger TRIGGER counter None
value-type Absolute
value 0
test-type PositiveComparison
delta INT64 1
events BOOL TRUE
The trigger is initialized as described in the definition of
TRIGGER, with an error being generated if necessary.
If the counter is None, the state of the alarm is set to
Inactive, else it is set to Active.
Whenever the trigger becomes TRUE, either as a result of
CreateAlarm this request or as the result of a SetCounter,
ChangeCounter, DestroyCounter, or ChangeAlarm request, an
AlarmNotify event is generated and the alarm is updated. The
alarm is updated by repeatedly adding delta to the value of
the trigger and reinitializing it until it becomes FALSE. If
this update would cause value to fall outside the range for
an INT64, or if the counter value is None, or if the delta
is 0 and test-type is PositiveComparison or
NegativeComparison, no change is made to value and the alarm
state is changed to Inactive before the event is generated.
No further events are generated by an Inactive alarm until a
ChangeAlarm or DestroyAlarm request is executed.
If the test-type is PositiveComparison or PositiveTransition
and delta is less than zero, or if the test-type is
NegativeComparison or NegativeTransition and delta is
greater than zero, a Match error is generated.
The events value enables or disables delivery of AlarmNotify
events to the requesting client. The alarm keeps a separate
event flag for each client so that other clients may select
to receive events from this alarm.
An AlarmNotify event is always generated at some time after
the execution of a CreateAlarm request. This will happen
immediately if the trigger is TRUE, or it will happen later
when the trigger becomes TRUE or the Alarm is destroyed.
id: ALARM
values-mask: CARD32
values-list: LISTofVALUE
Errors: Alarm,Counter,Value,Match
This request changes the parameters of an Alarm. All of the
parameters specified for the CreateAlarm request may be
changed using this request. The trigger is reinitialized and
an AlarmNotify event is generated if appropriate, as
ChangeAlarm explained in the description of the CreateAlarm request.
Changes to the events flag affect the event delivery to the
requesting client only and may be used by a client to select
or deselect event delivery from an alarm created by another
client.
The order in which attributes are verified and altered is
server-dependent. If an error is generated, a subset of the
attributes may have been altered.
alarm: ALARM
Errors: Alarm
DestroyAlarm This request destroys an alarm. An alarm is automatically
destroyed when the creating client is closed down if the
close-down mode is Destroy. When an alarm is destroyed, an
AlarmNotify event is generated with a state value of
Destroyed.
alarm: ALARM
=>
trigger: TRIGGER
delta: INT64
QueryAlarm events: ALARMEVENTMASK
state: ALARMSTATE
Errors: Alarm
This request retrieves the current parameters for an Alarm.
client-resource: XID
priority: INT32
Errors: Match
This request changes the scheduling priority of the client
that created client-resource. If client-resource is None,
then the priority for the client making the request is
changed. A Match error is generated if client-resource is
not None and does not name an existing resource in the
server. For any two priority values, A and B, A is higher
priority if and only if A is greater than B.
The priority of a client is set to 0 when the initial client
connection is made.
SetPriority The effect of different client priorities depends on the
particular implementation of the extension, and in some
cases it may have no effect at all. However, the intention
is that higher priority clients will have their requests
executed before those of lower priority clients.
For most animation applications, it is desirable that
animation clients be given priority over nonrealtime
clients. This improves the smoothness of the animation on a
loaded server. Because a server is free to implement very
strict priorities, processing requests for the highest
priority client to the exclusion of all others, it is
important that a client that may potentially monopolize the
whole server, such as an animation that produces continuous
output as fast as it can with no rate control, is run at low
rather than high priority.
client-resource: XID
=>
priority: INT32
Errors: Match
GetPriority This request returns the scheduling priority of the client
that created client-resource. If client-resource is None,
then the priority for the client making the request is
returned. A Match error is generated if client-resource is
not None and does not name an existing resource in the
server.
drawable: DRAWABLE
id: FENCE
initially-triggered: BOOL
Errors: IDChoice,Alloc
CreateFence
This request creates a fence on the screen associated with
drawable and assigns the specified id to it. The fence is in
the triggered state iff initially-triggered is TRUE. There
are no clients waiting on the fence.
fence: FENCE
Errors: Fence
This request puts the given fence in the triggered state
after all rendering from previous requests that affects
resources owned by the fence's screen has completed. This
includes requests from other clients if those requests have
been dispatched. This request has no visible effects if the
fence was already in the triggered state. A Fence error is
TriggerFence generated if fence does not name a valid fence.
Note that the given fence's state is not necessarily
directly modified by this request. The state change need
only be queued to occur after the required rendering has
completed. Clients should take care to not assume the fence
will be in the triggered state in subsequent requests, such
as those that operate on the given fence immediately.
AwaitFence should first be issued if subsequent requests
require the fence to be in the triggered state.
fence: FENCE
Errors: Fence,Match
This request immediately puts the given fence in the not
triggered state. A Match error is generated if the fence is
not in the triggered state. A Fence error is generated if
ResetFence fence does not name a valid fence.
See the warnings above regarding TriggerFence's delayed
effect. In particular, a TriggerFence request immediately
followed by a ResetFence request is likely to result in a
Match error. An AwaitFence request should be issued between
the two.
fence: FENCE
Errors: Fence
This request destroys the given fence. All clients waiting
DestroyFence on this fence are released. A fence is destroyed
automatically when the connection to the client that created
the fence is closed if the close-down mode is DestroyAll. A
Fence error is generated if fence does not name a valid
fence.
fence: FENCE
=>
triggered: BOOL
QueryFence Errors: Fence
This request returns TRUE if the given fence is triggered,
or FALSE if it is not triggered. A Fence error is generated
if fence does not name a valid fence.
fence-list: LISTofFENCE
Errors: Fence,Alloc
When this request is executed, the processing of further
AwaitFence requests for the client is blocked until one or more of the
fences in fence-list reaches the triggered state. If any of
the fences are already in the triggered state, request
processing resumes immediately. A Fence error is generated
if any member of fence-list does not name a valid fence.
Events
counter: COUNTER
wait-value: INT64
counter-value: INT64
time: TIME
count: CARD16
destroyed: BOOL
CounterNotify events may be generated when a client becomes
unblocked after an Await request has been processed. The
CounterNotify wait-value is the value being waited for, and counter-value is
the actual value of the counter at the time the event was
generated. The destroyed flag is TRUE if this request was
generated as the result of the destruction of the counter and
FALSE otherwise. The time is the server time at which the event
was generated.
When a client is unblocked, all the CounterNotify events for the
Await request are generated contiguously. If count is 0, there
are no more events to follow for this request. If count is n,
there are at least n more events to follow.
alarm: ALARM
counter-value: INT64
alarm-value: INT64
state: ALARMSTATE
time: TIME
AlarmNotify An AlarmNotify event is generated when an alarm is triggered.
alarm-value is the test value of the trigger in the alarm when it
was triggered, counter-value is the value of the counter that
triggered the alarm, and time is the server time at which the
event was generated. The state is the new state of the alarm. If
state is Inactive, no more events will be generated by this alarm
until a ChangeAlarm request is executed, the alarm is destroyed,
or the counter for the alarm is destroyed.
Chapter 2. Encoding
Table of Contents
Encoding New Types
Encoding Errors
Encoding Requests
Encoding Events
Please refer to the X11 Protocol Encoding document as this section uses
syntactic conventions established there and references types defined there.
The name of this extension is "SYNC".
Encoding New Types
The following new types are used by the extension.
ALARM: CARD32
ALARMSTATE:
0 Active
1 Inactive
2 Destroyed
COUNTER: CARD32
INT64: 64-bit signed integer
SYSTEMCOUNTER:
4 COUNTER counter
8 INT64 resolution
2 n length of name in bytes
n STRING8 name
p pad,p=pad(n+2)
TESTTYPE:
0 PositiveTransition
1 NegativeTransition
2 PositiveComparison
3 NegativeComparison
TRIGGER:
4 COUNTER counter
4 VALUETYPE wait-type
8 INT64 wait-value
4 TESTTYPE test-type VALUETYPE:
0 Absolute
1 Relative
WAITCONDITION:
20 TRIGGER trigger
8 INT64 event threshold
FENCE: CARD32
An INT64 is encoded in 8 bytes with the most significant 4 bytes first followed
by the least significant 4 bytes. Within these 4-byte groups, the byte ordering
determined during connection setup is used.
Encoding Errors
Counter
1 0 Error
1 Base + 0 code
2 CARD16 sequence number
4 CARD32 bad counter
2 CARD16 minor opcode
1 CARD8 major opcode
21 unused
Alarm
1 0 Error
1 Base + 1 code
2 CARD16 sequence number
4 CARD32 bad alarm
2 CARD16 minor opcode
1 CARD8 major opcode
21 unused
Fence
1 0 Error
1 Base + 2 code
2 CARD16 sequence number
4 CARD32 bad fence
2 CARD16 minor opcode
1 CARD8 major opcode
21 unused
Encoding Requests
Initialize
1 CARD8 major opcode
1 0 minor opcode
2 2 request length
1 CARD8 major version
1 CARD8 minor version
2 unused
=>
1 1 Reply
1 unused
2 CARD16 sequence number
4 0 reply length
1 CARD8 major version
1 CARD8 minor version
2 unused
20 unused
ListSystemCounters
1 CARD8 major opcode
1 1 minor opcode
2 1 request length
=>
1 1 Reply
1 unused
2 CARD16 sequence number
4 0 reply length
4 INT32 list length
20 unused
4n list of SYSTEMCOUNTER system counters
CreateCounter
1 CARD8 major opcode
1 2 minor opcode
2 4 request length
4 COUNTER id
8 INT64 initial value
DestroyCounter
1 CARD8 major opcode
1 6 minor opcode^[1]
2 2 request length
4 COUNTER counter
=>
1 1 Reply
1 unused
2 CARD16 sequence number
4 0 reply length
8 INT64 counter value
16 unused
Await
1 CARD8 major opcode
1 7 minor opcode^[2]
2 1 + 7*n request length
28n LISTofWAITCONDITION wait conditions
ChangeCounter
1 CARD8 major opcode
1 4 minor opcode^[3]
2 4 request length
4 COUNTER counter
8 INT64 amount
SetCounter
1 CARD8 major opcode
1 3 minor opcode^[4]
2 4 request length
4 COUNTER counter
8 INT64 value
CreateAlarm
1 CARD8 major opcode
1 8 minor opcode
2 3+n request length
4 ALARM id
4 BITMASK values mask
#x00000001 counter
#x00000002 value-type
#x00000004 value
#x00000008 test-type
#x00000010 delta
#x00000020 events
4n LISTofVALUE values
VALUES
4 COUNTER counter
4 VALUETYPE value-type
8 INT64 value
4 TESTTYPE test-type
8 INT64 delta
4 BOOL events
ChangeAlarm
1 CARD8 major opcode
1 9 minor opcode
2 3+n request length
4 ALARM id
4 BITMASK values mask
encodings as for CreateAlarm
4n LISTofVALUE values
encodings as for CreateAlarm
DestroyAlarm
1 CARD8 major opcode
1 11 minor opcode^[5]
2 2 request length
4 ALARM alarm
QueryAlarm
1 CARD8 major opcode
1 10 minor opcode^[6]
2 2 request length
4 ALARM alarm
=>
1 1 Reply
1 unused
2 CARD16 sequence number
4 2 reply length
20 TRIGGER trigger
8 INT64 delta
1 BOOL events
1 ALARMSTATE state
2 unused
SetPriority
1 CARD8 major opcode
1 12 minor opcode
2 3 request length
4 CARD32 id
4 INT32 priority
GetPriority
1 CARD8 major opcode
1 13 minor opcode
2 1 request length
4 CARD32 id
=>
1 1 Reply
1 unused
2 CARD16 sequence number
4 0 reply length
4 INT32 priority
20 unused
CreateFence
1 CARD8 major opcode
1 14 minor opcode
2 4 request length
4 DRAWABLE drawable
4 FENCE id
1 BOOL initially triggered
3 unused
TriggerFence
1 CARD8 major opcode
1 15 minor opcode
2 2 request length
4 FENCE id
ResetFence
1 CARD8 major opcode
1 16 minor opcode
2 2 request length
4 FENCE id
DestroyFence
1 CARD8 major opcode
1 17 minor opcode
2 2 request length
4 FENCE id
QueryFence
1 CARD8 major opcode
1 18 minor opcode
2 2 request length
4 FENCE id
=>
1 1 Reply
1 unused
2 CARD16 sequence number
4 0 reply length
1 BOOL triggered
23 unused
AwaitFence
1 CARD8 major opcode
1 19 minor opcode
2 1 + n request length
4*n LISTofFENCE wait conditions
Encoding Events
CounterNotify
1 Base + 0 code
1 0 kind
2 CARD16 sequence number
4 COUNTER counter
8 INT64 wait value
8 INT64 counter value
4 TIME timestamp
2 CARD16 count
1 BOOL destroyed
1 unused
AlarmNotify
1 Base + 1 code
1 1 kind
2 CARD16 sequence number
4 ALARM alarm
8 INT64 counter value
8 INT64 alarm value
4 TIME timestamp
1 ALARMSTATE state
3 unused
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^[1] A previous version of this document gave an incorrect minor opcode
^[2] A previous version of this document gave an incorrect minor opcode.
^[3] A previous version of this document gave an incorrect minor opcode.
^[4] A previous version of this document gave an incorrect minor opcode.
^[5] A previous version of this document gave an incorrect minor opcode.
^[6] A previous version of this document gave an incorrect minor opcode.
Generated by dwww version 1.15 on Wed Jun 26 01:55:51 CEST 2024.