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IXP400 Software
Buffer Management
Programmer’s Guide IXP400 Software Version 2.0 April 2005
Document Number: 252539, Revision: 007 45
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.
20 ix_rsvd
24
ix_pktlen
28
ix_priv(Reserved)
Table 1. Internal IX_MBUF Field Format (Sheet 2 of 2)
0123
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
Parameter type: IX_MBUF *
Return type: IX_MBUF *
Description: Returns a 32-bit pointer to the
next buffer in the packet
32-bit pointer to the next buffer in a
chain (linked list) of buffers. NULL
entry marks end of chain.
Yes, where buffer chaining is
supported.
IX_OSAL_MBUF_NEXT_PKT_IN_CHAIN_
PTR
Parameter type: IX_MBUF *
Return type: IX_MBUF *
Description: Returns a 32-bit pointer to the
first buffer in the next packet in the packet
chain
32-bit pointer to the next packet in a
chain (linked list) of packets. NULL
entry marks end of chain. Each
packet in the chain may consist of a
chain of buffers.
No. Packet chaining is not supported
by IXP400 Software.
IX_OSAL_MBUF_MDATA
Parameter type: IX_MBUF *
Return type: char *
Description: Returns a pointer to the first
byte of the buffer data
32-bit pointer to the data section of a
buffer. The data section typically
contains the payload of a network
buffer.
Yes. But does not get modified by the
access-layer
IX_OSAL_MBUF_MLEN
Parameter type: IX_MBUF *
Return type: int
Description: Returns the number of octets of
valid data in the data section of the buffer
Lengths (octets) of valid data in the
data section of the buffer.
Yes.
IX_OSAL_MBUF_TYPE
Parameter type: IX_MBUF *
Return type: unsigned char
Description: Returns the type field of the
buffer
Buffer type Yes, by some components.