该代码首先对ECG信号进行消噪过滤，并且对信号进行平方，加窗等处理-The code first ECG signal denoising filter, and the square of the signal, windowing and other processing

《SDL入门教程》，SDL是一款C语言图形库，能用来进行窗口化图形等一系列开发，这是一本入门的书。-SDL introductory tutorial SDL graphics library is a C language can be used to windowing graphical development, this is an introductory book.