PxMsgRequest()

Create a message object together with a data area.

APPLIES TO

8.2.0

SYNOPSIS

PxMsg_t PxMsgRequest (PxSize_t msgsize, PxMc_t McId, PxOpool_t OpoolId);

ARGUMENTS

msgsize: Size of the message

McId: Memory class where to take the data area from

OpoolId: Object pool where to take the message object from

RETURN VALUES

Valid message handle on success
Invalid message handle on failure

ERROR CODES

PXERR_OPOOL_ILLOPOOL

The passed object pool handle is invalid

PXERR_MC_ILLMC

The passed memory class handle is invalid

PXERR_MC_NOMEM

Not enough memory

PXERR_ACCESS_RIGHT

The calling task has not the right to access the object pool or the memory class

PXERR_GLOBAL_ILLEGAL_CORE

The passed memory class is not on the same core

PXERR_OBJ_NOOBJ

No free object is available

PXERR_EVENT_ZERO

The given event mask is zero

PXERR_OBJ_ABORTED

Request aborted by an event

PXERR_OBJ_ILLOBJ

The passed object handle is not valid

PXERR_MC_ILLTYPE

Illegal MC type

PXERR_MC_SIZETOOBIG

Fixed block size too small to satisfy the request

PXERR_INIT_ILLMCTYPE

The type for PXMcSystemdefault is different from PXMcVarsized, PXMcVarsizedAdjusted and PXMcVarsizedAligned

PXERR_REQUEST_ABORTED

Request aborted

PXERR_MC_DAMAGED_BLOCK

The block in the memory class has been damaged

PXERR_MC_INCONSISTENCY

Inconsistency in memory class: blk

PXERR_MC_ILLSIZE

Insufficient block size

PXERR_MC_ILLALIGN

Invalid memory block or size alignment in memory insert

PXERR_INTERNAL_INCONSISTENCY

Inconsistency of internal structures

DESCRIPTION

The PxMsgRequest function creates a message with a data area of size msgsize specified in byte units. The data area is taken from memory class mc, and the message object is taken from object pool opool. The message object handle is returned. If there is no free object available, the PxMsgRequest waits until a free object is available.

The calling task becomes the (permanent) owner and the (temporary) user of the created message. The call fails, if the memory class does not contain sufficient memory to meet the request. A fatal PXROS error occurs, if mc is fixsized and its block size is smaller than msgsize. If msgsize is zero, no data buffer is requested and only the metadata of the message object can be used.

IMPLEMENTATION GUIDELINES

Before call

msgsize must be a plausible value given as a constant (V) or a variable (C).
McId must be a valid PXROS-HR memory class and the calling task must have the access right to take memory from this memory class (V). The validity of McId may also be checked by the PxMcIsValid macro (F). The memory class must be created on the same core as the caller runs on. The creator core id can be read with the macro PxMcCoreId and the own core id with PxGetCoreId (C). Typically the task’s default memory class PXMcTaskdefault is used for this purpose.
OpoolId must be a valid PXROS-HR object pool and the calling task must have the access right to take objects from this object pool (V). The validity of OpoolId may also be checked by the PxOpoolIsValid macro (F). The object pool must be created on the same core as the caller runs on. The creator core id can be read with the macro PxOpoolCoreId and the own core id with PxGetCoreId (C). Typically the task’s default object pool PXOpoolTaskdefault is used for this purpose.

After call

The returned value is the id of type PxMsg_t. This id may be checked with one of the following macros:
- PxMsgIdIsValid() must be true.
- PxMsgIdGet() must not be _PXIllegalObjId.
- PxMsgIdError() must be PXERR_NOERROR otherwise the returned error code has to be interpreted (C).

Best Practice

PxMsgRequest may block, if no PXROS-HR object or memory is available. If blocking calls are prohibited, PxMsgRequest_NoWait() should be used instead.

SEE ALSO

USAGE

#include "pxdef.h"

PxMsg_t msgHnd = PxMsgRequest (64, McId, OpoolId)

if (!PxMsgIdIsValid (msgHnd)) {
    // Report error;
}