28335 求助

哪位大侠帮我解释下：  （contronsuit 里面 2833xqep.h )

v.ElecTheta = (v.PolePairs*v.MechTheta) -floor(v.PolePairs*v.MechTheta); /* Q24 = Q0*Q24 */

为什么要减去后面的floor部分？

为什么前面的 v.MechTheta= v.MechScaler*v.RawTheta; 中 v.MechScaler 要定义成q30 格式？？

部分代码是这样的：：：

#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 */ \