ucos 初始化OSTaskCreate() 源码分析 2
//系统任务创建
OSTaskCreate 任务创建
INT8U OSTaskCreate (void (*task)(void *p_arg), //任务函数地址
void *p_arg, //任务函数传递参数
OS_STK *ptos, //任务的栈底
INT8U prio) //任务优先级
{
OS_STK *psp;
INT8U err;
#if OS_CRITICAL_METHOD == 3u /* 中断模式 */
OS_CPU_SR cpu_sr = 0u;
#endif
//基本上不用
#ifdef OS_SAFETY_CRITICAL_IEC61508
// 不允许创建任务
if (OSSafetyCriticalStartFlag == OS_TRUE) {
OS_SAFETY_CRITICAL_EXCEPTION();
}
#endif
#if OS_ARG_CHK_EN > 0u
if (prio > OS_LOWEST_PRIO) { /* 确定任务优先级范围正确 */
return (OS_ERR_PRIO_INVALID);
}
#endif
OS_ENTER_CRITICAL();
if (OSIntNesting > 0u) { /* 确定没有嵌套中断 */
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_CREATE_ISR);
}
if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* 当前优先级任务没有存在 */
OSTCBPrioTbl[prio] = OS_TCB_RESERVED;
OS_EXIT_CRITICAL();
psp = OSTaskStkInit(task, p_arg, ptos, 0u); /* 任务堆栈初始化 并给赋给psp */
//OS_TCBInit(优先级指针,堆栈指针,栈底指针,任务标志符,堆栈容量,扩展指针,选择项)
err = OS_TCBInit(prio, psp, (OS_STK *)0, 0u, 0u, (void *)0, 0u);
if (err == OS_ERR_NONE) { //
if (OSRunning == OS_TRUE) { /*运行状态 */
OS_Sched(); //系统调度
}
} else {
OS_ENTER_CRITICAL();
//创建失败，当前优先级任务清零
OSTCBPrioTbl[prio] = (OS_TCB *)0;/* Make this priority available to others */
OS_EXIT_CRITICAL();
}
return (err);
}
OS_EXIT_CRITICAL();
return (OS_ERR_PRIO_EXIST);
}
查询cortex-M3手册 可以知道为什么寄存器这么配置这么配置
OSTaskStkInit() 任务栈初始化
OS_STK *OSTaskStkInit (void (*task)(void *p_arg), void *p_arg, OS_STK *ptos, INT16U opt)
{
OS_STK *stk;
(void)opt; /* 'opt' is not used, prevent warning */
stk = ptos; /* Load stack pointer */
/* Registers stacked as if auto-saved on exception */
*(stk) = (INT32U)0x01000000L; /* xPSR */
*(--stk) = (INT32U)task; /* Entry Point */
*(--stk) = (INT32U)0xFFFFFFFEL; /* R14 (LR) */
*(--stk) = (INT32U)0x12121212L; /* R12 12代表寄存器12 */
*(--stk) = (INT32U)0x03030303L; /* R3 03代表寄存器3 */
*(--stk) = (INT32U)0x02020202L; /* R2 */
*(--stk) = (INT32U)0x01010101L; /* R1 */
*(--stk) = (INT32U)p_arg; /* R0 : argument */
/* Remaining registers saved on process stack */
*(--stk) = (INT32U)0x11111111L; /* R11 */
*(--stk) = (INT32U)0x10101010L; /* R10 */
*(--stk) = (INT32U)0x09090909L; /* R9 */
*(--stk) = (INT32U)0x08080808L; /* R8 */
*(--stk) = (INT32U)0x07070707L; /* R7 */
*(--stk) = (INT32U)0x06060606L; /* R6 */
*(--stk) = (INT32U)0x05050505L; /* R5 */
*(--stk) = (INT32U)0x04040404L; /* R4 */
return (stk);
}
//单个TCB 初始化
OS_TCBInit() TCB块初始化
INT8U OS_TCBInit (INT8U prio, //优先级
OS_STK *ptos, //栈顶
OS_STK *pbos, //栈底
INT16U id, //任务id
INT32U stk_size, //任务大小
void *pext, //任务数据扩展
INT16U opt)
{
OS_TCB *ptcb;
#if OS_CRITICAL_METHOD == 3u /* 进入临界区模式Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#if OS_TASK_REG_TBL_SIZE > 0u
INT8U i;
#endif
OS_ENTER_CRITICAL();
ptcb = OSTCBFreeList;
if (ptcb != (OS_TCB *)0) { //空闲任务链表中取出一个
OSTCBFreeList = ptcb->OSTCBNext; /* 更新空闲TCB列表 */
OS_EXIT_CRITICAL();
ptcb->OSTCBStkPtr = ptos; /* 堆栈指针 */
ptcb->OSTCBPrio = prio; /* 优先级 */
ptcb->OSTCBStat = OS_STAT_RDY; /* 状态就绪 */
ptcb->OSTCBStatPend = OS_STAT_PEND_OK; /* 清除阻塞状态 */
ptcb->OSTCBDly = 0u; /* 不延时 */
/*****************************************************************
************************ 一般用不到 ******************************/
#if OS_TASK_CREATE_EXT_EN > 0u
ptcb->OSTCBExtPtr = pext; /* Store pointer to TCB extension */
ptcb->OSTCBStkSize = stk_size; /* Store stack size */
ptcb->OSTCBStkBottom = pbos; /* Store pointer to bottom of stack */
ptcb->OSTCBOpt = opt; /* Store task options */
ptcb->OSTCBId = id; /* Store task ID */
#else
pext = pext; /* Prevent compiler warning if not used */
stk_size = stk_size;
pbos = pbos;
opt = opt;
id = id;
#endif
#if OS_TASK_DEL_EN > 0u
ptcb->OSTCBDelReq = OS_ERR_NONE; //删除请求清空
#endif
// 将任务优先级转换 存到bitx,bity中
#if OS_LOWEST_PRIO <= 63u /* 进行优先级转换 */
ptcb->OSTCBY = (INT8U)(prio >> 3u);
ptcb->OSTCBX = (INT8U)(prio & 0x07u);
#else
ptcb->OSTCBY = (INT8U)((INT8U)(prio >> 4u) & 0xFFu);
ptcb->OSTCBX = (INT8U) (prio & 0x0Fu);
#endif
/* Pre-compute BitX and BitY */
ptcb->OSTCBBitY = (OS_PRIO)(1uL << ptcb->OSTCBY);
ptcb->OSTCBBitX = (OS_PRIO)(1uL << ptcb->OSTCBX);
#if (OS_EVENT_EN)
ptcb->OSTCBEventPtr = (OS_EVENT *)0; /* Task is not pending on an event */
#if (OS_EVENT_MULTI_EN > 0u)
ptcb->OSTCBEventMultiPtr = (OS_EVENT **)0; /* Task is not pending on any events */
#endif
#endif
#if (OS_FLAG_EN > 0u) && (OS_MAX_FLAGS > 0u) && (OS_TASK_DEL_EN > 0u)
ptcb->OSTCBFlagNode = (OS_FLAG_NODE *)0; /* Task is not pending on an event flag */
#endif
#if (OS_MBOX_EN > 0u) || ((OS_Q_EN > 0u) && (OS_MAX_QS > 0u))
ptcb->OSTCBMsg = (void *)0; /* No message received */
#endif
#if OS_TASK_PROFILE_EN > 0u
ptcb->OSTCBCtxSwCtr = 0uL; /* Initialize 分析 variables */
ptcb->OSTCBCyclesStart = 0uL;
ptcb->OSTCBCyclesTot = 0uL;
ptcb->OSTCBStkBase = (OS_STK *)0;
ptcb->OSTCBStkUsed = 0uL;
#endif
#if OS_TASK_NAME_EN > 0u
ptcb->OSTCBTaskName = (INT8U *)(void *)"?";
#endif
#if OS_TASK_REG_TBL_SIZE > 0u /* Initialize the task variables */
for (i = 0u; i < OS_TASK_REG_TBL_SIZE; i++) {
ptcb->OSTCBRegTbl[i] = 0u;
}
#endif
OSTCBInitHook(ptcb); //用户钩子初始化
OSTaskCreateHook(ptcb); /* Call user defined hook */
OS_ENTER_CRITICAL();
OSTCBPrioTbl[prio] = ptcb; //将创建好的TCB 赋给 当前任务优先级TCB
//连接以前创建的tcb
ptcb->OSTCBNext = OSTCBList; /* 添加到TCB链表中 */
ptcb->OSTCBPrev = (OS_TCB *)0;
if (OSTCBList != (OS_TCB *)0) {
OSTCBList->OSTCBPrev = ptcb; //建立双向连接
}
OSTCBList = ptcb; //新链表添加到TCB链表
OSRdyGrp |= ptcb->OSTCBBitY; /* Make task ready to run */
OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;
OSTaskCtr++; /* Increment the #tasks counter */
OS_EXIT_CRITICAL();
return (OS_ERR_NONE);
}
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_NO_MORE_TCB);
}
任务创建主要做的事情：判断优先级范围是否正常、判断是否有中断嵌套、判断当前优先级TCB是否存在、将参数写入任务栈中，初始化TCB，将值赋给TCB中，将新建的TCB添加到TCB链表中。