官方例程中编码器测速程序高低速怎么区分

如下是官方编码器测速的程序：

//**** High Speed Calculation using QEP Position counter ****//
// Check unit Time out-event for speed calculation:
// Unit Timer is configured for 100Hz in INIT function

if(EQep1Regs.QFLG.bit.UTO==1) // If unit timeout (one 100Hz period)
{
/** Differentiator **/
// The following lines calculate position = (x2-x1)/4000 (position in 1 revolution)
pos16bval=(unsigned int)EQep1Regs.QPOSLAT; // Latched POSCNT value
tmp = (long)((long)pos16bval*(long)p->mech_scaler); // Q0*Q26 = Q26
tmp &= 0x03FFF000;
tmp = (int)(tmp>>11); // Q26 -> Q15
tmp &= 0x7FFF;
newp=_IQ15toIQ(tmp);
oldp=p->oldpos;

if (p->DirectionQep==0) // POSCNT is counting down
{
if (newp>oldp)
Tmp1 = - (_IQ(1) - newp + oldp); // x2-x1 should be negative
else
Tmp1 = newp -oldp;
}
else if (p->DirectionQep==1) // POSCNT is counting up
{
if (newp<oldp)
Tmp1 = _IQ(1) + newp - oldp;
else
Tmp1 = newp - oldp; // x2-x1 should be positive
}

if (Tmp1>_IQ(1))
p->Speed_fr = _IQ(1);
else if (Tmp1<_IQ(-1))
p->Speed_fr = _IQ(-1);
else
p->Speed_fr = Tmp1;

// Update the electrical angle
p->oldpos = newp;

// Change motor speed from pu value to rpm value (Q15 -> Q0)
// Q0 = Q0*GLOBAL_Q => _IQXmpy(), X = GLOBAL_Q
p->SpeedRpm_fr = _IQmpy(p->BaseRpm,p->Speed_fr);
//=======================================

EQep1Regs.QCLR.bit.UTO=1; // Clear interrupt flag
}

//**** Low-speed computation using QEP capture counter ****//
if(EQep1Regs.QEPSTS.bit.UPEVNT==1) // Unit position event
{
if(EQep1Regs.QEPSTS.bit.COEF==0) // No Capture overflow
temp1=(unsigned long)EQep1Regs.QCPRDLAT; // temp1 = t2-t1
else // Capture overflow, saturate the result
temp1=0xFFFF;

p->Speed_pr = _IQdiv(p->SpeedScaler,temp1); // p->Speed_pr = p->SpeedScaler/temp1
Tmp1=p->Speed_pr;

if (Tmp1>_IQ(1))
p->Speed_pr = _IQ(1);
else
p->Speed_pr = Tmp1;

// Convert p->Speed_pr to RPM
if (p->DirectionQep==0) // Reverse direction = negative
p->SpeedRpm_pr = -_IQmpy(p->BaseRpm,p->Speed_pr); // Q0 = Q0*GLOBAL_Q => _IQXmpy(), X = GLOBAL_Q
else // Forward direction = positive
p->SpeedRpm_pr = _IQmpy(p->BaseRpm,p->Speed_pr); // Q0 = Q0*GLOBAL_Q => _IQXmpy(), X = GLOBAL_Q

EQep1Regs.QEPSTS.all=0x88; // Clear Unit position event flag
// Clear overflow error flag
}

高速是采用M法测量速度  低速采用T法测速  

问题是怎么判断是用M法还是T法呢？在程序中没有进行判断啊，仅靠这两个状态标志位够用用吗？不需要人为在程序中添加其他判断条件吗？

如果不是，那么是不是在eQEP初始化的时候做了哪些小技巧？多谢指教！

 if(EQep1Regs.QFLG.bit.UTO==1) // If unit timeout (one 100Hz period)

 if(EQep1Regs.QEPSTS.bit.UPEVNT==1) // Unit position event