17.5.5 Mailbox information

The mailbox information defines ID number: mbxid, Attribute: mbxatr, Maximum message priority: maxmpri, Reserved for future use: mprihd for a mailbox.

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

The following shows the mailbox information format.

CRE_MBX (mbxid, { mbxatr, maxmpri, mprihd });

The items constituting the mailbox information are as follows.

1 ) ID number: mbxid

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

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 mbxid   value

2 ) Attribute: mbxatr

Specifies the attribute for a mailbox.
The keyword that can be specified for mbxatr is TA_TFIFO, TA_TPRI, TA_MFIFO and TA_MPRI.

[Task queuing method]

TA_TFIFO: Task wait queue is in FIFO order.

TA_TPRI: Task wait queue is in task priority order.

[Message queuing method]

TA_MFIFO: Message wait queue is in FIFO order.

TA_MPRI: Message wait queue is in message priority order.

3 ) Maximum message priority: maxmpri

Specifies the maximum message priority for a mailbox.
A value from 0x1 to 0x7fff can be specified for maxmpri.

Note maxmpri is valid only when TA_MPRI is specified for mqueue.
It is invalid when TA_MFIFO is specified for mqueue.

4 ) Reserved for future use: mprihd

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