,QWHJUDWLRQ ZLWK 2SHUDWLQJ 6\VWHPV

7LJKW ,QWHJUDWLRQ
6LJQDOV
The signal header consists of a struct with information needed to handle
the signal inside an SDL system. The signal header struct is defined in
the RTOS-specific file sct.h.
typedef struct xSignalHeaderStruct *xSignalHeader;
typedef struct xSignalHeaderStruct {
int SignalCode;
xSignalHeader Pre, Suc;
SDL_PId Sender;
void *SigP;
#ifdef X_ONE_TASK_PER_INSTANCE_SET
SDL_PId Receiver;
#endif
#ifdef XMSC_TRACE
int SignalId;
int IsTimer;
#endif
} xSignalHeaderRec;
The signal header stores SignalCode, in this case an integer, two pointers
Pre and Suc used when saving the signal in the save queue, and
Sender, holding the SDL_PId of the sending SDL process. In the Instance
Set Model there is an extra parameter Receiver, necessary to
make a distinction between the SDL processes in an instance set task.
If the signal contains parameters they are allocated in the same function
call. Example:
OutputSignalPtr = xAlloc (sizeof (xSignalHeaderRec)
+ sizeof(yPDef_z05_s2));
The second parameter to the xAlloc function is a struct representing the
signal parameters of the signal. In this case, with one integer, it is defined
in the following way:
typedef struct {
SIGNAL_VARS
SDL_Integer Param1;
} yPDef_z05_s2;
The macro SIGNAL_VARS is in most RTOS empty.
There is an extra element in the SignalHeader defined as a void pointer.
This pointer SigP is set to point to the parameter area.
OutputSignalPtr->SigP = OutputSignalPtr+1;
July 2003 Telelogic Tau 4.5 User’s Manual ,um-st1