ZCOM Tables and Data Structures

ZLU Tables

Table 3-7

Individual ZLU Data Structure (zlu_type) (Continued)

Field NameField DescriptionField Type

Size

(Bytes)

spare1

Reserved, not used

int

4

ZCKSUM - ZLU checksum

The checksum is used as an integrity check to ensure that a ZLU has not been altered while it is active. It is the 16-bit binary sum of bytes 3 to 18 of the ZLU entry (with any overflow discarded). It is calculated when the ZLU table entry is created.

ZLTYPE - Type of ZLU

The ZLU type values are shown in Table 3-8. The type value is also used to indicate whether the ZLU is defined.

Table 3-8 ZLU Type Values

Type

Description

 

 

0ZLU is not defined

1ZLU is local terminal (ZPOINT is a logical terminal number *)

2ZLU is a local program (ZPOINT is a queue number)

3ZLU is mapped (ZPOINT is a mapped ZLU node number)

*The logical terminal number is allocated by TTGEN from the TTGEN configuration file.

ZPOINT - ZLU pointer or mapped node number

The field is used to link the ZLU with the entity it represents. The meaning of the field is given in the table under ZLTYPE.

ZMPZLU - Mapped ZLU number

If the ZLU is type 3 (mapped ZLU), then this is the ZLU number (on the node as given by ZPOINT) onto which this ZLU is being mapped. If ZLU is not type 3, ZMPZLU is set to zero.

ZMPZCS - Mapped ZLU checksum

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Chapter 3