KSSTREAM_POINTER_OFFSET structure (ks.h)

The KSSTREAM_POINTER_OFFSET structure indexes bytes or mappings within a frame.

Syntax

typedef struct _KSSTREAM_POINTER_OFFSET {
  union {
    PUCHAR     Data;
    PKSMAPPING Mappings;
  };
  PUCHAR Data;
  PVOID  Alignment;
  ULONG  Count;
  ULONG  Remaining;
} KSSTREAM_POINTER_OFFSET, *PKSSTREAM_POINTER_OFFSET;

Members

Data

A pointer to a buffer containing input data or a buffer to which data is to be output. Specify Data if the minidriver does not set the KSPIN_FLAG_GENERATE_MAPPINGS flag in the Flags member of KSPIN_DESCRIPTOR_EX.

Mappings

A pointer to the first element in an array of KSMAPPING structures. Specify Mappings if the minidriver sets the KSPIN_FLAG_GENERATE_MAPPINGS flag in the Flags member of KSPIN_DESCRIPTOR_EX. In this case, the Mappings array describes contiguous chunks of physical memory that the client can use to set up a scatter/gather DMA operation with hardware.

Alignment

Count

If Data is specified above, Count contains the total number of bytes of data available in the Data buffer. If Mappings is specified above, Count contains the total number of mappings in the Mappings table. Count does not change unless the stream pointer moves to a different Frame.

Remaining

This member specifies a value of type ULONG that indicates the number of bytes or mappings remaining at and ahead of the given stream pointer. This value is equal to Count minus the number of bytes or mappings that have been processed. Remaining starts equal to Count and decreases as the stream pointer moves forward.

Remarks

See also AVStream DMA Services.

Requirements

See also

KSMAPPING

KSSTREAM_POINTER