1：任务控制块
首先看看ucos中任务控制块的数据结构为：
typedef struct os_tcb {
OS_STK *OSTCBStkPtr; /* Pointer to current top of stack */
#if OS_TASK_CREATE_EXT_EN > 0
void *OSTCBExtPtr; /* Pointer to user definable data for TCB extension */
OS_STK *OSTCBStkBottom; /* Pointer to bottom of stack */
INT32U OSTCBStkSize; /* Size of task stack (in number of stack elements) */
INT16U OSTCBOpt; /* Task options as passed by OSTaskCreateExt() */
INT16U OSTCBId; /* Task ID (0..65535) */
#endif
struct os_tcb *OSTCBNext; /* Pointer to next TCB in the TCB list */
struct os_tcb *OSTCBPrev; /* Pointer to previous TCB in the TCB list */
#if (OS_EVENT_EN) || (OS_FLAG_EN > 0)
OS_EVENT *OSTCBEventPtr; /* Pointer to event control block */
#endif
#if (OS_EVENT_EN) && (OS_EVENT_MULTI_EN > 0)
OS_EVENT **OSTCBEventMultiPtr; /* Pointer to multiple event control blocks */
#endif
#if ((OS_Q_EN > 0) && (OS_MAX_QS > 0)) || (OS_MBOX_EN > 0)
void *OSTCBMsg; /* Message received from OSMboxPost() or OSQPost() */
#endif
#if (OS_FLAG_EN > 0) && (OS_MAX_FLAGS > 0)
#if OS_TASK_DEL_EN > 0
OS_FLAG_NODE *OSTCBFlagNode; /* Pointer to event flag node */
#endif
OS_FLAGS OSTCBFlagsRdy; /* Event flags that made task ready to run */
#endif
INT16U OSTCBDly; /* Nbr ticks to delay task or, timeout waiting for event */
INT8U OSTCBStat; /* Task status */
INT8U OSTCBStatPend; /* Task PEND status */
INT8U OSTCBPrio; /* Task priority (0 == highest) */
INT8U OSTCBX; /* Bit position in group corresponding to task priority */
INT8U OSTCBY; /* Index into ready table corresponding to task priority */
#if OS_LOWEST_PRIO <= 63
INT8U OSTCBBitX; /* Bit mask to access bit position in ready table */
INT8U OSTCBBitY; /* Bit mask to access bit position in ready group */
#else
INT16U OSTCBBitX; /* Bit mask to access bit position in ready table */
INT16U OSTCBBitY; /* Bit mask to access bit position in ready group */
#endif
#if OS_TASK_DEL_EN > 0
INT8U OSTCBDelReq; /* Indicates whether a task needs to delete itself */
#endif
#if OS_TASK_PROFILE_EN > 0
INT32U OSTCBCtxSwCtr; /* Number of time the task was switched in */
INT32U OSTCBCyclesTot; /* Total number of clock cycles the task has been running */
INT32U OSTCBCyclesStart; /* Snapshot of cycle counter at start of task resumption */
OS_STK *OSTCBStkBase; /* Pointer to the beginning of the task stack */
INT32U OSTCBStkUsed; /* Number of bytes used from the stack */
#endif
#if OS_TASK_NAME_SIZE > 1
INT8U OSTCBTaskName[OS_TASK_NAME_SIZE];
#endif
} OS_TCB;
任务控制块记录了：任务的堆栈指针，任务当前的运行状态，任务的优先级等属性。其中上面结构中任务状态
INT8U OSTCBStat; /* Task status */的可取值范围如下：
2：任务控制块链表
ucso中系统默认创建了：OS_MAX_TASKS + OS_N_SYS_TASKS个任务控制块。
OS_EXT OS_TCB OSTCBTbl[OS_MAX_TASKS + OS_N_SYS_TASKS]; /* Table of TCBs */
当创建任务的时候，执行从已经创建好的任务控制块中取出一个空闲的OS_TCB来使用。其有关初始化函数如下：
static void OS_InitTCBList (void)
{
INT8U i;
OS_TCB *ptcb1;
OS_TCB *ptcb2；
OS_MemClr((INT8U *)&OSTCBTbl[0], sizeof(OSTCBTbl)); /* Clear all the TCBs */
OS_MemClr((INT8U *)&OSTCBPrioTbl[0], sizeof(OSTCBPrioTbl)); /* Clear the priority table */
ptcb1 = &OSTCBTbl[0];
ptcb2 = &OSTCBTbl[1];
for (i = 0; i < (OS_MAX_TASKS + OS_N_SYS_TASKS - 1); i++) { /* Init. list of free TCBs */
ptcb1->OSTCBNext = ptcb2;
#if OS_TASK_NAME_SIZE > 1
ptcb1->OSTCBTaskName[0] = '?'; /* Unknown name */
ptcb1->OSTCBTaskName[1] = OS_ASCII_NUL;
#endif
ptcb1++;
ptcb2++;
}
ptcb1->OSTCBNext = (OS_TCB *)0; /* Last OS_TCB */
#if OS_TASK_NAME_SIZE > 1
ptcb1->OSTCBTaskName[0] = '?'; /* Unknown name */
ptcb1->OSTCBTaskName[1] = OS_ASCII_NUL;
#endif
OSTCBList = (OS_TCB *)0; /* TCB lists initializations */
OSTCBFreeList = &OSTCBTbl[0];
}
其中OSTCBList 中存放的是已经创建的任务的任务控制块即此任务控制块已经配初始化过。
OSTCBFreeList 中存放的是空闲的尚未被使用的任务控制块。
经过上面的函数初始化之后，系统所有的任务控制块形成了一个空闲链表OSTCBFreeList。
在任务创建函数中OS_TCBInit(）函数中如下代码：
和
在ucso代码中定义了多个与TCB相关的全局变量，其定义如下：
其中OSTCBCur表示当前运行的TCB，OSTCBFreeList：指向当前空闲的任务控制块链表，OSTCBHighRdy：指向任务就绪表中任务优先级最高的任务的TCB，OSTCBPrioTbl：指向某个任务优先级的TCB指针。
