NET_RING structure (ring.h)

Specifies a buffer comprised of one or more NET_PACKET or NET_FRAGMENT structures.

Syntax

typedef struct _NET_RING {
  UINT16        OSReserved1;
  UINT16        ElementStride;
  UINT32        NumberOfElements;
  UINT32        ElementIndexMask;
  UINT32        EndIndex;
  union {
    UINT32 OSReserved0;
    void   *OSReserved2[4];
  } DUMMYUNIONNAME;
  UINT32        BeginIndex;
  UINT32        NextIndex;
  void          *Scratch;
  unsigned char Buffer[ANYSIZE_ARRAY];
} NET_RING;

Members

OSReserved1

Reserved. Client drivers must not read or write to this value.

ElementStride

A read-only byte offset from the start of one element to the start of the next. Use ((BYTE*)p + ElementStride) to obtain the address of the next element.

NumberOfElements

A read-only value that indicates the number of packets in the ring buffer, which is always a power of two, and greater than one.

ElementIndexMask

A read-only UINT32 mask that can be used to efficiently clamp an index to [0, NumberOfElements). The client can use this value to calculate an index that wraps around the ring buffer. Use the identity (x % NumberofElements) == (x & ElementIndexMask).

EndIndex

Specifies the read-only index of the last element that is owned by the client driver in the inclusive range [0, NumberOfElements - 1].

DUMMYUNIONNAME

A union that contains the OSReserved0 and OSReserved2 members.

DUMMYUNIONNAME.OSReserved0

Reserved. Client drivers must not read or write to this value.

DUMMYUNIONNAME.OSReserved2[4]

Reserved. Client drivers must not read or write to this value.

BeginIndex

Specifies the index of the first element owned by the client driver in the inclusive range [0, NumberOfElements - 1].

NextIndex

Specifies the index of the next element that needs processing. For optional use by the client driver.

Scratch

A pointer to a buffer that the client driver may use for any purpose.

Buffer[ANYSIZE_ARRAY]

A byte array that contains the elements in the net ring. Typically, a client driver calls NetRingGetPacketAtIndex or NetRingGetFragmentAtIndex to access the elements of the ring buffer.

Remarks

The NET_RING structure is a generic ring buffer, optimized for efficient access from a single thread. A NET_RING contains NET_PACKET or NET_FRAGMENT elements.

For more info about packet and fragment ring buffers, see Packet descriptors and extensions.

For more info about using net rings, see Introduction to net rings.

Requirements