F28335-qep使用问题

请ti人帮忙解释一下这段代码，我自己有很多疑惑，十分感谢

#define QEP_MACRO(m,v)                   \
                        \
/* Check the rotational direction */               \
     v.DirectionQep = (*eQEP[m]).QEPSTS.bit.QDF;            \
                        \
/* Check the position counter for EQEP1 */              \
     v.RawTheta = (*eQEP[m]).QPOSCNT + v.CalibratedAngle;          \
                            \
     if (v.RawTheta < 0)                  \
       v.RawTheta = v.RawTheta + (*eQEP[m]).QPOSMAX;           \
     else if (v.RawTheta > (*eQEP[m]).QPOSMAX)             \
       v.RawTheta = v.RawTheta – (*eQEP[m]).QPOSMAX;           \
                              \
/* Compute the mechanical angle */                \
 v.MechTheta= v.MechScaler*v.RawTheta;              \
/* Compute the electrical angle  */                \
    v.ElecTheta = (v.PolePairs*v.MechTheta) -floor(v.PolePairs*v.MechTheta); /* Q24 = Q0*Q24 */ \
                           \
/* Check an index occurrence*/                 \
     if ((*eQEP[m]).QFLG.bit.IEL == 1)                  \
     {                        \
      v.IndexSyncFlag = 0x00F0;                \
        v.QepCountIndex = (*eQEP[m]).QPOSILAT;             \
     (*eQEP[m]).QCLR.bit.IEL = 1; /* Clear interrupt flag */        \
     }                       \
                        \
/* Check unit Time out-event for speed calculation: */           \
/* Unit Timer is configured for 100Hz in INIT function*/          \
 if((*eQEP[m]).QFLG.bit.UTO == 1)               \
    {                       \
       /***** Low Speed Calculation   ****/            \
     if(((*eQEP[m]).QEPSTS.bit.COEF || (*eQEP[m]).QEPSTS.bit.CDEF))       \
    { /* Capture Counter overflowed, hence do no compute speed*/       \
     (*eQEP[m]).QEPSTS.all = 0x000C;              \
     }                      \
     else if((*eQEP[m]).QCPRDLAT!=0xffff)             \
      /* Compute lowspeed using capture counter value*/         \
      v.QepPeriod = (*eQEP[m]).QCPRDLAT;             \
    }

#endif // __F2833X_QEP_H__