基于 CPU 的精确计时器，时钟频率越高，计时越准，用于系统程序运行时间的测试。

CPU 的精确计时器 This class implements an MFC wrapper class for the Pentium-specific (or better) time stamp counter which can be accessed using the "RDTSC" assembly language instruction. This counter has a resolution in terms of PCLKS (processor clocks)

一个可以精确到微妙级别的计时器，c代码编写。利用cpu的主频。-An accurate timer to the subtle level, c coding. Cpu frequency of use.