signed portBASE_TYPE xTaskGenericCreate( pdTASK_CODE pxTaskCode, const signed char * const pcName, unsigned short usStackDepth, void *pvParameters, unsigned portBASE_TYPE uxPriority, xTaskHandle *pxCreatedTask, portSTACK_TYPE *puxStackBuffer, const xMemoryRegion * const xRegions )
{
signed portBASE_TYPE xReturn;
tskTCB * pxNewTCB;
configASSERT( pxTaskCode );
configASSERT( ( uxPriority < configMAX_PRIORITIES ) );
//分配任务TCB和堆栈
pxNewTCB = prvAllocateTCBAndStack( usStackDepth, puxStackBuffer );
if( pxNewTCB != NULL )
{
portSTACK_TYPE *pxTopOfStack;
#if( portUSING_MPU_WRAPPERS == 1 )
portBASE_TYPE xRunPrivileged;
if( ( uxPriority & portPRIVILEGE_BIT ) != 0U )
{
xRunPrivileged = pdTRUE;
}
else
{
xRunPrivileged = pdFALSE;
}
uxPriority &= ~portPRIVILEGE_BIT;
#endif
//判断堆栈增长方式是否是由高到低增长
#if( portSTACK_GROWTH < 0 )
{
pxTopOfStack = pxNewTCB->pxStack + ( usStackDepth - ( unsigned short ) 1 );
//保持堆栈为字节对齐？
pxTopOfStack = ( portSTACK_TYPE * ) ( ( ( portPOINTER_SIZE_TYPE ) pxTopOfStack ) & ( ( portPOINTER_SIZE_TYPE ) ~portBYTE_ALIGNMENT_MASK ) );
configASSERT( ( ( ( unsigned long ) pxTopOfStack & ( unsigned long ) portBYTE_ALIGNMENT_MASK ) == 0UL ) );
}
#else
{
pxTopOfStack = pxNewTCB->pxStack;
configASSERT( ( ( ( unsigned long ) pxNewTCB->pxStack & ( unsigned long ) portBYTE_ALIGNMENT_MASK ) == 0UL ) );
pxNewTCB->pxEndOfStack = pxNewTCB->pxStack + ( usStackDepth - 1 );
}
#endif
//TCB初始化
prvInitialiseTCBVariables( pxNewTCB, pcName, uxPriority, xRegions, usStackDepth );
#if( portUSING_MPU_WRAPPERS == 1 )
{
pxNewTCB->pxTopOfStack = pxPortInitialiseStack( pxTopOfStack, pxTaskCode, pvParameters, xRunPrivileged );
}
#else
{
//汇编语言对堆栈进行初始化
pxNewTCB->pxTopOfStack = pxPortInitialiseStack( pxTopOfStack, pxTaskCode, pvParameters );
}
#endif
portALIGNMENT_ASSERT_pxCurrentTCB( ( ( ( unsigned long ) pxNewTCB->pxTopOfStack & ( unsigned long ) portBYTE_ALIGNMENT_MASK ) == 0UL ) );
if( ( void * ) pxCreatedTask != NULL )
{
*pxCreatedTask = ( xTaskHandle ) pxNewTCB;
}
taskENTER_CRITICAL();
{
uxCurrentNumberOfTasks++;//更新系统任务数
if( pxCurrentTCB == NULL )
{
pxCurrentTCB = pxNewTCB;
if( uxCurrentNumberOfTasks == ( unsigned portBASE_TYPE ) 1 )
{
//如果当前任务数为1的话，则证明米有初始化就绪列表，等待列表，挂起列表等
//初始化就绪列表的时候，定义优先级为一个数据数组，则每个数据数组的元素代表一个优先级
//其他列表则没有这么复杂 直接定义 不区分优先级
prvInitialiseTaskLists();
}
}
else
{
//比较，将当前最高的优先级赋给pxCurrentTCB
if( xSchedulerRunning == pdFALSE )
{
if( pxCurrentTCB->uxPriority <= uxPriority )
{
pxCurrentTCB = pxNewTCB;
}
}
}
//更新uxTopUsedPriority，方便查询的时候直接从uxTopUsedPriority开始查询
if( pxNewTCB->uxPriority > uxTopUsedPriority )
{
uxTopUsedPriority = pxNewTCB->uxPriority;
}
#if ( configUSE_TRACE_FACILITY == 1 )
{
pxNewTCB->uxTCBNumber = uxTCBNumber;
}
#endif
uxTCBNumber++;
//将任务添加到就绪列表中。当任务处于阻塞态的时候，从就绪列表中删除，加入到阻塞列表中。
prvAddTaskToReadyQueue( pxNewTCB );
xReturn = pdPASS;
traceTASK_CREATE( pxNewTCB );
}
taskEXIT_CRITICAL();
}
else
{
xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;
traceTASK_CREATE_FAILED();
}
if( xReturn == pdPASS )
{
if( xSchedulerRunning != pdFALSE )
{
if( pxCurrentTCB->uxPriority < uxPriority )
{
portYIELD_WITHIN_API();
}
}
}
return xReturn;
}