udi_buf_tag_t(3udi)

---

Buffer tag structure

SYNOPSIS

#include <udi.h>

typedef struct {

	udi_tagtype_t tag_type;

	udi_ubit32_t tag_value;

	udi_size_t tag_off;

	udi_size_t tag_len;

} udi_buf_tag_t;
 

MEMBERS tag_type is the type of tag represented by this tag structure. Although udi_tagtype_t is a bitmask type only one tag type may be specified in the udi_buf_tag_t structure (i.e. only one bit may be set).

tag_value is the value associated with this tag.

tag_off is the starting buffer data offset for which the tag applies.

tag_len is the length of data (in bytes) for which the tag applies. The tag_len value must not be zero.

DESCRIPTION The udi_buf_tag_t structure is used to describe a buffer tag. The range of data to which the tag applies is specified by the tag_off and tag_len fields; the tag_type specifies which type of tag is being described. The tag_value is the associated value for this tag (if any) as defined by the tag_type.

Table 13-2 Tag structure field usage

tag_typeUDI_BUFTAG_xxx	tag_value	tag_off	tag_len
BE16_CHECKSUM	16-bit checksum	start of region checksummed as big-endian 16-bit values	number of bytes to checksum (if odd, an extra byte value of 0 is assumed: 16-bit array length = (tag_len+1)/2)
SET_iBE16_CHECKSUM	buffer offset at which to write the 16-bit big-endian checksum of the buffer data	start of region to generate a 16-bit big-endian checksum over	number of bytes to checksum
SET_TCP_CHECKSUM	unused	start of IP header (including options) followed by TCP header and TCP data	total byte length of IP header (including options), TCP header, and TCP data
SET_UDP_CHECKSUM	unused	start of IP header (including options) followed by UDP header and UDP data	total byte length of IP header (including options), UDP header, and UDP data
TCP_CKSUM_GOOD	checksum value (if known, otherwise zero)	start of TCP header	total byte length of TCP header and TCP data
UDP_CKSUM_GOOD	checksum value (if known, otherwise zero)	start of UDP header	total byte length of UDP header and UDP data
IP_CKSUM_GOOD	checksum value (if known, otherwise zero)	start of IP header	total byte length of IP header including options
TCP_CKSUM_BAD	unused	start of TCP header	total byte length of TCP header and TCP data
UDP_CKSUM_BAD	unused	start of UDP header	total byte length of UDP header and UDP data
IP_CKSUM_BAD	unused	start of IP header	total byte length of IP header including options
DRIVER1...DRIVER8	driver-defined	driver-defined	driver-defined

REFERENCES udi_buf_tag_set, udi_buf_tag_get