Reference Guide

ZCOM Tables and Data Structures
Queue Header
Chapter 3 101
Queue Header
The queue header area contains the descriptor block for all the ZCOM
subsystem queues. The first queue is used to link the free buffers in the
buffer pool.
Figure 3-7 Queue Header Area
Free Queue Header (zfqh_type), queue 0, basically is the same as the
other buffer queues. However, its fields are viewed and used slightly
differently from the other queues. Its size is the same as a buffer queue.
Queue Header 0 (Free Queue)
Queue Header 1
…
…
Queue Header n
Table 3-27 Free Queue Header Structure (zfqh_type)
Field Name Field Description Field Type
Size
(Bytes)
QNMSG Number of messages on queue uns.int 4
QALLOC Number of allocated messages uns.int 4
QHEAD Pointer to first message on queue pointer 8
QTAIL Pointer to last message on queue pointer 8
QMMAX Historical max number of messages uns.int 4
QTMSG Total messages through queue uns.int 4
QBYTES Number of bytes on queue uns.int 4
QWAITER Number of waiters on this queue uns.short 2
QFLAG Queue flags uns.short 2