KSCLOCK_DISPATCH structure (ks.h)

The KSCLOCK_DISPATCH structure contains the callbacks required for a pin to implement a clock object.

Syntax

typedef struct _KSCLOCK_DISPATCH {
  PFNKSPINSETTIMER       SetTimer;
  PFNKSPINCANCELTIMER    CancelTimer;
  PFNKSPINCORRELATEDTIME CorrelatedTime;
  PFNKSPINRESOLUTION     Resolution;
} KSCLOCK_DISPATCH, *PKSCLOCK_DISPATCH;

Members

SetTimer

Optionally contains a pointer to an alternate function to use in generating DPC timer callbacks based on a presentation time. If this is set, this function is used to set timers based on deltas to the current presentation time in order to generate event notifications. If an alternate function is specified to set timers, a corresponding CancelTimer function must also be provided. This is set to NULL if the default KeSetTimerEx function is used to approximate the next notification time. This would normally be set only if a KeSetTimerEx function was being used. The function must have the same characteristics as the default function.

The function should be prototyped as follows:

BOOLEAN SetTimer (IN PKSPIN Pin,
    IN PKTIMER Timer,
    IN LARGE_INTEGER DueTime,
    IN PKDPC Dpc);

See the documentation for KeSetTimerEx for details on implementation of this function. Any client implementation must behave in a similar manner.

CancelTimer

Optionally contains an alternate function to use in canceling outstanding timer callbacks. If an alternate function is provided to cancel timers, a corresponding SetTimer function must also be provided. This is set to NULL if the default KeCancelTimer function is to be used. The function must have the same characteristics as the default function.

The function should be prototyped as follows:

BOOLEAN CancelTimer (IN PKSPIN Pin,
    IN PKTIMER Timer);

See the documentation for KeCancelTimer for details on the implementation of this function. Any client implementation must behave in a similar manner.

CorrelatedTime

A pointer to a function to retrieve the current clock time and a correlated system time as an atomic operation. The function should be prototyped as follows:

LONGLONG CorrelatedTime (IN PKSPIN Pin,
    OUT PLONGLONG SystemTime);

The current clock time should be returned and the current system time should be placed in SystemTime.

Resolution

A pointer to a function to specify the resolution of the clock. This corresponds to the KS property KSPROPERTY_CLOCK_RESOLUTION. This function should report the granularity in terms of 100-nanosecond units. For more information, see the KS documentation on KSPROPERTY_CLOCK_RESOLUTION.

The function should be prototyped as follows:

void Resolution (IN PKSPIN Pin,
        OUT PKSRESOLUTION Resolution);

Requirements

Requirement	Value
Minimum supported client	Available in Microsoft Windows XP and later operating systems and in Microsoft DirectX 8.0 and later versions.
Header	ks.h (include Ks.h)

See also

KDPC

KSPIN

KSPIN_DISPATCH

KSPROPERTY_CLOCK_RESOLUTION

KSRESOLUTION

KeSetTimerEx