Intel IXP400 manual Internal Ixmbuf Field Format Sheet 2, Ixmbuf Field Details Sheet 1

Intel® IXP400 Software

Buffer Management

Table 1. Internal IX_MBUF Field Format (Sheet 2 of 2)

20

24

28

0 1 2 3

ix_rsvd

ix_pktlen

ix_priv(Reserved)

A set of macros are provided for the IXP400 software to access each of the fields in the buffer structure. Each macro takes a single parameter – a pointer to the buffer itself. Each macro returns the value stored in the field. More detail on the field, their usage, and the macros are detailed in the table below.

Note: The data pointer IX_OSAL_MBUF_MDATA could be aligned on a 16 bit boundary to help align an IP header on a 32 bit boundary.

Table 2. IX_MBUF Field Details (Sheet 1 of 2)

Field / MACRO	Purpose	Used by Access-Layer?
IX_OSAL_MBUF_NEXT_BUFFER_IN_PK
T_PTR	32-bit pointer to the next buffer in a
Parameter type: IX_MBUF *		Yes, where buffer chaining is
	chain (linked list) of buffers. NULL
Return type: IX_MBUF *		supported.
	entry marks end of chain.
Description: Returns a 32-bit pointer to the
next buffer in the packet
IX_OSAL_MBUF_NEXT_PKT_IN_CHAIN_
PTR	32-bit pointer to the next packet in a
Parameter type: IX_MBUF *
	chain (linked list) of packets. NULL	No. Packet chaining is not supported
Return type: IX_MBUF *	entry marks end of chain. Each
		by IXP400 Software.
Description: Returns a 32-bit pointer to the	packet in the chain may consist of a
	chain of buffers.
first buffer in the next packet in the packet
chain
IX_OSAL_MBUF_MDATA	32-bit pointer to the data section of a
Parameter type: IX_MBUF *		Yes. But does not get modified by the
	buffer. The data section typically
Return type: char *
	contains the payload of a network	access-layer
Description: Returns a pointer to the first	buffer.
byte of the buffer data
IX_OSAL_MBUF_MLEN
Parameter type: IX_MBUF *	Lengths (octets) of valid data in the	Yes.
Return type: int
	data section of the buffer.
Description: Returns the number of octets of
valid data in the data section of the buffer
IX_OSAL_MBUF_TYPE
Parameter type: IX_MBUF *	Buffer type	Yes, by some components.
Return type: unsigned char
Description: Returns the type field of the
buffer

Programmer’s Guide	IXP400 Software Version 2.0	April 2005
	Document Number: 252539, Revision: 007	45