ucos sem信號量 源碼分析
信號量的建立操做
OS_EVENT *OSSemCreate (INT16U cnt)
{
OS_EVENT *pevent;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#ifdef OS_SAFETY_CRITICAL_IEC61508
if (OSSafetyCriticalStartFlag == OS_TRUE) {
OS_SAFETY_CRITICAL_EXCEPTION();
return ((OS_EVENT *)0);
}
#endif
if (OSIntNesting > 0u) { /* See if called from ISR ... */
return ((OS_EVENT *)0); /* ... can't CREATE from an ISR */
}
OS_ENTER_CRITICAL();
pevent = OSEventFreeList; /* Get next free event control block */
if (OSEventFreeList != (OS_EVENT *)0) { /* 判斷是否爲還有 事件塊 若是還有鏈表就日後移動，指向下一個 事件塊 */
OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;
}
OS_EXIT_CRITICAL();
if (pevent != (OS_EVENT *)0) { /* 當前事件塊不爲空就進行賦值 */
pevent->OSEventType = OS_EVENT_TYPE_SEM;
pevent->OSEventCnt = cnt; /* Set semaphore value */
pevent->OSEventPtr = (void *)0; /* Unlink from ECB free list */
#if OS_EVENT_NAME_EN > 0u
pevent->OSEventName = (INT8U *)(void *)"?";
#endif
OS_EventWaitListInit(pevent); /* Initialize to 'nobody waiting' on sem. */
}
return (pevent);
}
OS_EventWaitListInit() 清空事件表
void OS_EventWaitListInit (OS_EVENT *pevent)
{
INT8U i;
pevent->OSEventGrp = 0u; /* No task waiting on event */
for (i = 0u; i < OS_EVENT_TBL_SIZE; i++) {
pevent->OSEventTbl[i] = 0u;
}
}
OSSemPend() 任務 添加到 事件任務
void OSSemPend (OS_EVENT *pevent,
INT32U timeout, //多少時間沒有接收到 也添加到就緒隊列
INT8U *perr)
{
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#ifdef OS_SAFETY_CRITICAL //這個是留給本身寫的
if (perr == (INT8U *)0) {
OS_SAFETY_CRITICAL_EXCEPTION();
return;
}
#endif
#if OS_ARG_CHK_EN > 0u
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*perr = OS_ERR_PEVENT_NULL;
return;
}
#endif
if (pevent->OSEventType != OS_EVENT_TYPE_SEM) { /* 非法的事件塊類型 */
*perr = OS_ERR_EVENT_TYPE;
return;
}
if (OSIntNesting > 0u) { /* See if called from ISR ... */
*perr = OS_ERR_PEND_ISR; /* ... can't PEND from an ISR */
return;
}
if (OSLockNesting > 0u) { /* See if called with scheduler locked ... */
*perr = OS_ERR_PEND_LOCKED; /* ... can't PEND when locked */
return;
}
OS_ENTER_CRITICAL();
if (pevent->OSEventCnt > 0u) { /* 信號量大於0 有效.. */
pevent->OSEventCnt--; /* ... decrement semaphore only if positive. */
OS_EXIT_CRITICAL();
*perr = OS_ERR_NONE;
return;
}
/* Otherwise, must wait until event occurs */
OSTCBCur->OSTCBStat |= OS_STAT_SEM; /* Resource not available, pend on semaphore */
OSTCBCur->OSTCBStatPend = OS_STAT_PEND_OK;
OSTCBCur->OSTCBDly = timeout; /* Store pend timeout in TCB */
OS_EventTaskWait(pevent); /*將任務 變爲阻塞狀態 */
OS_EXIT_CRITICAL();
OS_Sched(); /* 找到最高優先級運行 */
/************************************************************************
** 爲何會到這裏，勉強猜想 OSTimeTick() 當時間到了時，任務恢復
** 接着上次到這裏運行，感受不對
************************************************************************/
OS_ENTER_CRITICAL();
switch (OSTCBCur->OSTCBStatPend) { /* See if we timed-out or aborted */
case OS_STAT_PEND_OK:
*perr = OS_ERR_NONE;
break;
case OS_STAT_PEND_ABORT:
*perr = OS_ERR_PEND_ABORT; /* Indicate that we aborted */
break;
case OS_STAT_PEND_TO: //time out TO 時間溢出
default:
OS_EventTaskRemove(OSTCBCur, pevent); //時間到了，從事件中移除
*perr = OS_ERR_TIMEOUT; /* Indicate that we didn't get event within TO */
break;
}
OSTCBCur->OSTCBStat = OS_STAT_RDY; /* Set task status to ready */
OSTCBCur->OSTCBStatPend = OS_STAT_PEND_OK; /* Clear pend status */
OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0; /* Clear event pointers */
#if (OS_EVENT_MULTI_EN > 0u)
OSTCBCur->OSTCBEventMultiPtr = (OS_EVENT **)0;
#endif
OS_EXIT_CRITICAL();
}
OSPost()發送消息 將事件中的任務 添加到就緒隊列中
INT8U OSSemPost (OS_EVENT *pevent)
{
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#if OS_ARG_CHK_EN > 0u
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent'*/
return (OS_ERR_PEVENT_NULL);
}
#endif
if (pevent->OSEventType != OS_EVENT_TYPE_SEM) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0u) { /* See if any task waiting for semaphore */
/* Ready HPT waiting on event */
(void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_SEM, OS_STAT_PEND_OK);
OS_EXIT_CRITICAL();
OS_Sched(); /* Find HPT ready to run */
return (OS_ERR_NONE);
}
if (pevent->OSEventCnt < 65535u) { /* Make sure semaphore will not overflow */
pevent->OSEventCnt++; /* Increment semaphore count to register event */
OS_EXIT_CRITICAL();
return (OS_ERR_NONE);
}
OS_EXIT_CRITICAL(); /* 通常不太可能到這裏 */
return (OS_ERR_SEM_OVF);
}
等待事件的任務 轉到 就緒任務 OS_EventTaskRdy( );
INT8U OS_EventTaskRdy (OS_EVENT *pevent, //事件
void *pmsg, //消息 只在MAILBOXEs and QUEUEs時應用
INT8U msk, //清除OS_STAT_SEM OS_STAT_MBOX標誌
INT8U pend_stat) //任務狀態
{
OS_TCB *ptcb;
INT8U y;
INT8U x;
INT8U prio;
#if OS_LOWEST_PRIO > 63u
OS_PRIO *ptbl;
#endif
//這裏 得到事件隊列中的任務的優先級 而後賦給到 TCB 就緒任務中 這樣就能夠被系統調度
#if OS_LOWEST_PRIO <= 63u
y = OSUnMapTbl[pevent->OSEventGrp]; /* Find HPT waiting for message */
x = OSUnMapTbl[pevent->OSEventTbl[y]];
prio = (INT8U)((y << 3u) + x); /* Find priority of task getting the msg */
#else
if ((pevent->OSEventGrp & 0xFFu) != 0u) { /* Find HPT waiting for message */
y = OSUnMapTbl[ pevent->OSEventGrp & 0xFFu];
} else {
y = OSUnMapTbl[(OS_PRIO)(pevent->OSEventGrp >> 8u) & 0xFFu] + 8u;
}
ptbl = &pevent->OSEventTbl[y];
if ((*ptbl & 0xFFu) != 0u) {
x = OSUnMapTbl[*ptbl & 0xFFu];
} else {
x = OSUnMapTbl[(OS_PRIO)(*ptbl >> 8u) & 0xFFu] + 8u;
}
prio = (INT8U)((y << 4u) + x); /* Find priority of task getting the msg */
#endif
ptcb = OSTCBPrioTbl[prio]; /* Point to this task's OS_TCB */
ptcb->OSTCBDly = 0u; /* Prevent OSTimeTick() from readying task */
#if ((OS_Q_EN > 0u) && (OS_MAX_QS > 0u)) || (OS_MBOX_EN > 0u)
ptcb->OSTCBMsg = pmsg; /* Send message directly to waiting task */
#else
pmsg = pmsg; /* Prevent compiler warning if not used */
#endif
ptcb->OSTCBStat &= (INT8U)~msk; /* Clear bit associated with event type */
ptcb->OSTCBStatPend = pend_stat; /* Set pend status of post or abort */
/* See if task is ready (could be susp'd) */
if ((ptcb->OSTCBStat & OS_STAT_SUSPEND) == OS_STAT_RDY) {
//這裏就是 傳值到 就緒任務表中 系統就能夠調度了
OSRdyGrp |= ptcb->OSTCBBitY; /* Put task in the ready to run list */
OSRdyTbl[y] |= ptcb->OSTCBBitX;
}
//這裏 把事件任務刪除 他的做用(恢復源任務優先級)已經完成，全部刪除
OS_EventTaskRemove(ptcb, pevent); /* Remove this task from event wait list */
#if (OS_EVENT_MULTI_EN > 0u)
if (ptcb->OSTCBEventMultiPtr != (OS_EVENT **)0) { /* Remove this task from events' wait lists */
OS_EventTaskRemoveMulti(ptcb, ptcb->OSTCBEventMultiPtr);
ptcb->OSTCBEventPtr = (OS_EVENT *)pevent;/* Return event as first multi-pend event ready*/
}
#endif
return (prio);
}
事件任務 刪除 OS_EventTaskRemove
void OS_EventTaskRemove (OS_TCB *ptcb,
OS_EVENT *pevent)
{
INT8U y;
y = ptcb->OSTCBY;
pevent->OSEventTbl[y] &= (OS_PRIO)~ptcb->OSTCBBitX; /* Remove task from wait list */
if (pevent->OSEventTbl[y] == 0u) {
pevent->OSEventGrp &= (OS_PRIO)~ptcb->OSTCBBitY;
}
}
任務 添加到 事件任務 OS_EventTaskWait
void OS_EventTaskWait (OS_EVENT *pevent)
{
INT8U y;
OSTCBCur->OSTCBEventPtr = pevent; /* Store ptr to ECB in TCB */
//將事件表中任務優先級 置1 即將 任務 添加到 事件任務表（這裏優先級同樣是爲了在得到信號量是，還原到就緒任務 隊列中
pevent->OSEventTbl[OSTCBCur->OSTCBY] |= OSTCBCur->OSTCBBitX; /* Put task in waiting list */
pevent->OSEventGrp |= OSTCBCur->OSTCBBitY;
y = OSTCBCur->OSTCBY; /* Task no longer ready */
OSRdyTbl[y] &= (OS_PRIO)~OSTCBCur->OSTCBBitX;
// 這裏將 OSRdyGrp 清零 即從就緒任務表中 將任務 刪除（這樣就不會被調度了）
if (OSRdyTbl[y] == 0u) { /* Clear event grp bit if this was only task pending */
OSRdyGrp &= (OS_PRIO)~OSTCBCur->OSTCBBitY;
}
}
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相關文章
- 1. ucos 互斥信號量 源碼分析
- 2. 信號量sem
- 3. linux sem信號量使用
- 4. 轉：ucos信號量理解
- 5. FreeRTOS-信號量源碼分析
- 6. IPC主題二：信號量（sem）
- 7. 信號量分析
- 8. ucos 初始化OSTaskCreate() 源碼分析 2
- 9. Linux的信號量semaphore源碼解析
- 10. Sidekiq 信號處理源碼分析