关于官方例程中__meallow()函数的问题

各位大师，我发现电机控制库关于IDDK实现FCL的官方例程中好像__meallow();函数缺失，我把鼠标放在这个函数的地方然后按住F3键，CCS软件弹出Could not find symbol'_meallow' in index.那么问题来了，例程又是如何实现他的功能的呢，会不会是这个__meallow()函数已经是内置到芯片里面，然后这个函数直接调用的呢，还是其他什么原因呢？

else if(lsw == ENC_WAIT_FOR_INDEX) //ENC_WAIT_FOR_INDEX = 1 ENC等待索引状态
{
//
// lsw = ENC_WAIT_FOR_INDEX ---> Waiting for QEP index as rotor spins
// Detect the offset angle between alpha axis and QEP index location
// If QEP index pulse is found :-
// POSILAT captures POSCNT at the first INDEX pulse.
// Load POSINIT with POSILAT, so that at every future INDEX event,
// POSCNT is loaded (reset) with POSINIT
//

__meallow();

//
// Check the index occurrence
//
if(ClaQep.ptr->QFLG.all & CLA_QEP_FLAG_IEL_EVENT) // QFLG.bit.IEL
{
__mdebugstop();

//
// QPOSILAT updates on Index edge(IEL) - capture it into QPOSINIT
//
ClaQep.ptr->QPOSINIT = ClaQep.ptr->QPOSILAT;

//
// make QPOSCNT = QPOSINIT on future Index edge(s)
// ClaQep.ptr->QEPCTL.bit.IEI = IEI_RISING;
//
ClaQep.ptr->QEPCTL.all |= IEI_RISING;

//
// if QEP index pulse is found, change lsw to 'ENC_CALIBRATION_DONE'
//
lsw = ENC_CALIBRATION_DONE;
}