rcv_mbx

Outline

Receive from mailbox (waiting forever).

C format

 ER      rcv_mbx (ID mbxid, T_MSG **ppk_msg);

Parameter(s)

I/O	Parameter	Description
I	ID mbxid;	ID number of the mailbox from which a message is received.
O	T_MSG **ppk_msg;	Start address of the message packet received from the mailbox.

[Message packet: T_MSG]

typedef struct t_msg { struct t_msg *msgnext; /*Reserved for future use*/ } T_MSG;

[Message packet: T_MSG_PRI]

typedef struct t_msg_pri { struct t_msg msgque; /*Reserved for future use*/ PRI msgpri; /*Message priority*/ } T_MSG_PRI;

Explanation

This service call receives a message from the mailbox specified by parameter mbxid, and stores its start address in the area specified by parameter ppk_msg.

If no message could be received from the target mailbox (no messages were queued to the wait queue) when this service call is issued, this service call does not receive messages but queues the invoking task to the target mailbox wait queue and moves it from the RUNNING state to the WAITING state (message reception wait state).

The receiving WAITING state for a mailbox is cancelled in the following cases, and then moved to the READY state.

Receiving WAITING State for a Mailbox Cancel Operation	Return Value
A message was transmitted to the target mailbox as a result of issuing snd_mbx.	E_OK
A message was transmitted to the target mailbox as a result of issuing isnd_mbx.	E_OK
Forced release from waiting (accept rel_wai while waiting).	E_RLWAI
Forced release from waiting (accept irel_wai while waiting).	E_RLWAI

Note 1 Invoking tasks are queued to the target mailbox wait queue in the order defined during configuration (FIFO order or priority order).

Note 2 If the receiving WAITING state for a mailbox is forcibly released by issuing rel_wai or irel_wai, the contents of the area specified by parameter ppk_msg will be undefined.

Note 3 For details about the message packet, refer to "15.2.6 Message packet".

Return value

Macro	Value	Description
E_OK	0	Normal completion.
E_ID	-18	Invalid ID number. - mbxid < 0x0 - mbxid > Maximum ID number
E_CTX	-25	Context error. - 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 dispatching disabled state.
E_NOEXS	-42	Non-existent object. - Specified mailbox is not registered.
E_RLWAI	-49	Forced release from the WAITING state. - Accept rel_wai/irel_wai while waiting.