17.5.4 Data queue information

The data queue information defines ID number: dtqid, Attribute: dtqatr, Data count: dtqcnt, memory area name: sec_nam, Reserved for future use: dtq for a data queue.

The number of items that can be defined as data queue information is limited to one for each ID number.

The following shows the data queue information format.

CRE_DTQ (dtqid, { dtqatr, dtqcnt[:sec_nam], dtq });

The items constituting the data queue information are as follows.

1 ) ID number: dtqid

Specifies the ID number for a data queue.
A value from 0x1 to 0xff, or a name, can be specified for dtqid.

Note When a name is specified, the CF850V4 automatically assigns an ID number.
The CF850V4 outputs the relationship between a name and an ID number to the system information header file in the following format:

 #define dtqid   value

2 ) Attribute: dtqatr

Specifies the task queuing method for a data queue.
The keyword that can be specified for dtqatr is TA_TFIFO or TA_TPRI.

TA_TFIFO: Task wait queue is in FIFO order.

TA_TPRI: Task wait queue is in task priority order.

3 ) Data count: dtqcnt, memory area name: sec_nam

Specifies the maximum number of data units that can be queued to the data queue area of a data queue, and the name of the memory area secured for the data queue area.
Only values from 0x0 to 0xff can be specified for dtqcnt, and only memory area name sec_nam defined in Memory area information" can be specified for sec_nam.

Note If specification of sec_nam is omitted, the data queue is allocated to ".kernel_work" section.

4 ) Reserved for future use: dtq

System-reserved area.
Values that can be specified for dtq are limited to NULL characters.