目录
- 内核:调度(oc_core.c文件的函数)
- OS_TCB(任务控制块)初始化
- 任务控制块列表(ucos_ii.h文件的函数)
- 系统调用,主动让渡CPU
- 发生中断,强制当前任务让渡CPU
- 就绪表(ucos_ii.h文件的函数)
- 设置任务进入就绪态
- 设置任务脱离就绪态
- 在就绪表中找到优先级最高(数最小)的任务
内核:调度(oc_core.c文件的函数)
OS_TCB(任务控制块)初始化
INT8U OS_TCBInit (
INT8U prio,
OS_STK *ptos,
OS_STK *pbos,
INT16U id,
INT32U stk_size,
void *pext,
INT16U opt
);
任务控制块列表(ucos_ii.h文件的函数)
OS_EXT OS_TCB OSTCBTbl[OS_MAX_TASKS + OS_N_SYS_TASKS];
系统调用,主动让渡CPU
void OS_Sched (void)
{
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
OS_ENTER_CRITICAL();
if (OSIntNesting == 0u) /* Schedule only if all ISRs done and ... */
{
if (OSLockNesting == 0u) /* ... scheduler is not locked */
{
OS_SchedNew();
OSTCBHighRdy = OSTCBPrioTbl[OSPrioHighRdy];
if (OSPrioHighRdy != OSPrioCur) /* No Ctx Sw if current task is highest rdy */
{
#if OS_TASK_PROFILE_EN > 0u
OSTCBHighRdy->OSTCBCtxSwCtr++; /* Inc. # of context switches to this task */
#endif
OSCtxSwCtr++; /* Increment context switch counter */
OS_TASK_SW(); /* Perform a context switch */
}
}
}
OS_EXIT_CRITICAL();
}
发生中断,强制当前任务让渡CPU
void OSIntExit (void)
{
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
if (OSRunning == OS_TRUE)
{
OS_ENTER_CRITICAL();
if (OSIntNesting > 0u) /* Prevent OSIntNesting from wrapping */
{
OSIntNesting--;
}
if (OSIntNesting == 0u) /* Reschedule only if all ISRs complete ... */
{
if (OSLockNesting == 0u) /* ... and not locked. */
{
OS_SchedNew();
OSTCBHighRdy = OSTCBPrioTbl[OSPrioHighRdy];
if (OSPrioHighRdy != OSPrioCur) /* No Ctx Sw if current task is highest rdy */
{
#if OS_TASK_PROFILE_EN > 0u
OSTCBHighRdy->OSTCBCtxSwCtr++; /* Inc. # of context switches to this task */
#endif
OSCtxSwCtr++; /* Keep track of the number of ctx switches */
OSIntCtxSw(); /* Perform interrupt level ctx switch */
}
}
}
OS_EXIT_CRITICAL();
}
}
就绪表(ucos_ii.h文件的函数)
OS_EXT OS_PRIO OSRdyTbl[OS_RDY_TBL_SIZE]; /* Table of tasks which are ready to run */