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prcv_mbf
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Receive from message buffer (polling).
ER_UINT prcv_mbf (ID mbfid, VP msg);
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ID mbfid;
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ID number of the message buffer.
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VP msg;
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Pointer to store the message.
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- There is a message in the message buffer.
This service call takes out the oldest message from the message buffer and stores the message to the area specified by
msg and return the size of the message. As a result, the size of available space in the target message buffer increases by the amount calculated by the following expression.
The amount of increase = up4( Return value ) +
VTSZ_MBFTBL
In addition, this service call repeats the following processing until task in the transmission wait queue is lost or it becomes impossible to store the message in the message buffer.
- When there is a task in the transmission wait queue and there is available space in the message buffer for the message specified by the task in the top of the transmission wait queue, the task is unlinked from the transmission wait queue and moves from the WAITING state (message transmission wait state) to the READY state, or from the WAITING-SUSPENDED state to the SUSPENDED state. As a result, the size of available space in the target message buffer decreases by the amount calculated by the following expression.
The amount of decrease =up4( The message size sent by the task ) +
VTSZ_MBFTBL
- There is no message in the message buffer and there is a task in the transmission wait queue.
This service call stores the message specified by the task in the top of the transmission wait queue to the area pointed by the parameter
msg. As a result, the task is unlinked from the transmission wait queue and moves from the WAITING state (message transmission wait state) to the READY state, or from the WAITING-SUSPENDED state to the SUSPENDED state.
Note, this situation is caused only when the size of the message buffer is 0.
- There is no message in the message buffer and there is no task in the transmission wait queue.
This service call returns "E_TMOUT".
Note The
Maximum message size (max_msgsz) is defined during configuration. The size of the area pointed by msg must be larger than or equal to the maximum message size.
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- This service call was issued from a non-task.
- This service call was issued in the CPU locked state.
- This service call was issued in the status "PSW.IPL > kernel interrupt mask level".
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Normal completion (the size of the received message).
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