Thread attribute block

Each SylixOS thread has its own properties, including thread priority, stack information, thread parameters, etc. Each thread attribute block consists of a structure LW_CLASS_THREADATTR is composed of the following members:

typedef struct {
 PLW_STACK 	THREADATTR_pstkLowAddr; /* Low memory start address of all stack areas */
 size_t 	THREADATTR_stGuardSize; /* Stack alert area size */
 size_t 	THREADATTR_stStackByteSize;/* Total stack size (bytes) */
 UINT8 		THREADATTR_ucPriority; /* thread priority  */
 ULONG 		THREADATTR_ulOption; /* Task options */
 PVOID 		THREADATTR_pvArg; /* Thread parameters */
 PVOID 		THREADATTR_pvExt; /* Extended segment pointer */
} LW_CLASS_THREADATTR;

Users of SylixOS application development usually only need to care about the stack size, thread priority, task options and thread parameters. Other member operating systems will set them by default.

• The parameter stStackByteSize is the stack size (bytes);

• Parameter ucPriority is thread priority;
  In order to reasonably use thread priority, SylixOS sets some common priority values (the smaller the value, the higher the thread priority, and the system gives priority to scheduling), as shown above. In application development, generally, the priority of tasks should be between lw_prio_high and LW_PRIO_LOW, so as not to affect the system kernel threads as much as possible.

  Macro name	value
  LW_PRIO_HIGHEST	0
  LW_PRIO_LOWEST	255
  LW_PRIO_EXTREME	LW_PRIO_HIGHEST
  LW_PRIO_CRITICAL	50
  LW_PRIO_REALTIME	100
  LW_PRIO_HIGH	150
  LW_PRIO_NORMAL	200
  LW_PRIO_LOW	250
  LW_PRIO_IDLE	LW_PRIO_LOWEST

• Parameter ulOption is thread option;

  Macro name	explain
  LW_OPTION_THREAD_STK_CHK	Check the thread stack at run time
  LW_OPTION_THREAD_STK_CLR	The stack data is cleared when the thread is established
  LW_OPTION_THREAD_USED_FP	Save floating point arithmetic unit
  LW_OPTION_THREAD_SUSPEND	Blocking after thread creation
  LW_OPTION_THREAD_INIT	Initialize thread
  LW_OPTION_THREAD_SAFE	The established thread is in safe mode
  LW_OPTION_THREAD_DETACHED	Threads are not allowed to be merged
  LW_OPTION_THREAD_UNSELECT	This thread does not use the select function
  LW_OPTION_THREAD_NO_MONITOR	The kernel tracker has no effect on this thread
  LW_OPTION_THREAD_ UNPREEMPTIVE	Tasks cannot be preempted (currently not supported)
  LW_OPTION_THREAD_SCOPE_PROCESS	In process contention (currently not supported)

• Parameter pvArg is a thread parameter;

Thread attribute block operation interface

LW_API  
LW_CLASS_THREADATTR     API_ThreadAttrGetDefault(VOID);                 /*  Get default thread attribute block          */

LW_API  
LW_CLASS_THREADATTR     API_ThreadAttrGet(LW_OBJECT_HANDLE  ulId);      /*  Gets the current attribute block of the specified thread      */

LW_API ULONG            API_ThreadAttrBuild(PLW_CLASS_THREADATTR    pthreadattr,
                                            size_t                  stStackByteSize, 
                                            UINT8                   ucPriority, 
                                            ULONG                   ulOption, 
                                            PVOID                   pvArg);
                                                                        /*  Generate a thread attribute block          */
                                            
LW_API ULONG            API_ThreadAttrBuildEx(PLW_CLASS_THREADATTR    pthreadattr,
                                              PLW_STACK               pstkStackTop, 
                                              size_t                  stStackByteSize, 
                                              UINT8                   ucPriority, 
                                              ULONG                   ulOption, 
                                              PVOID                   pvArg,
                                              PVOID                   pvExt);
                                                                        /*  Generate an advanced thread attribute block      */

LW_API ULONG            API_ThreadAttrBuildFP(PLW_CLASS_THREADATTR    pthreadattr,
                                              PVOID                   pvFP);
                                                                        /*  Configure floating point operator context        */

LW_API ULONG            API_ThreadAttrBuildDefault(PLW_CLASS_THREADATTR    pthreadattr);
                                                                        /*  Generate a thread default attribute block      */
LW_API ULONG            API_ThreadAttrSetGuardSize(PLW_CLASS_THREADATTR    pthreadattr,
                                                   size_t                  stGuardSize);
                                                                        /*  Set stack alert size          */
LW_API ULONG            API_ThreadAttrSetStackSize(PLW_CLASS_THREADATTR    pthreadattr,
                                                   size_t                  stStackByteSize);
                                                                        /*  Set stack size                */
LW_API ULONG            API_ThreadAttrSetArg(PLW_CLASS_THREADATTR    pthreadattr,
                                             PVOID                   pvArg);
                                                                        /*  Set thread startup parameters            */

• API_ The threadattrget function is used to obtain the thread attribute block, and other interfaces are used to set the thread attribute block.

• API_ThreadAttrGetDefault returns a default value of the thread attribute block, while the API_ThreadAttrBuildDefault is to set a thread attribute block as the default value. In fact, the effect is the same.

• Other interfaces are a member that sets the thread attribute block separately.

• It is also possible to assign values directly through structure members without using these thread attribute block operation functions.

• The default thread attribute block values are as follows:

  Thread attribute block member	Default value
  THREADATTR_pstkLowAddr	LW_NULL
  THREADATTR_stGuardSize	LW_CFG_THREAD_DEFAULT_GUARD_SIZE
  THREADATTR_stStackByteSize	LW_CFG_THREAD_DEFAULT_STK_SIZE
  THREADATTR_ucPriority	LW_PRIO_NORMAL
  THREADATTR_ulOption	LW_OPTION_THREAD_STK_CHK
  THREADATTR_pvArg	LW_NULL
  THREADATTR_pvExt	LW_NULL

Sample code

    LW_CLASS_THREADATTR     threadattr  = API_ThreadAttrGetDefault();
    
    API_ThreadAttrBuild(&threadattr,
                        LW_CFG_THREAD_DISKCACHE_STK_SIZE,
                        LW_PRIO_T_SERVICE,
                        LW_CFG_DISKCACHE_OPTION | LW_OPTION_OBJECT_GLOBAL,
                        pdiskc);

	API_ThreadAttrSetStackSize(&threakattr, __LW_THREAD_MAIN_STK_SIZE);