CCS/UCD3138PFCEVM-026: PWR026_PFC: In the following codes .What 4096 and 32768 mean?

Those are all to support integer math.  The numbers we are dealing with are fractional numbers, so we could use floating point math.  But integer math is much faster on the ARM7.  So instead of using fractions, we multiply everything by powers of 2, in this case 2**15 and 2**12.  Then after we multiply by these constants, we do a shift right by 15 or 12 to scale back down to the correct result.  It's a standard trick, especially with integer DSPs.