最长的那个句子，求sum的赋值语句就是FIR滤波器的计算过程，将二进制乘法转化为移位运算。对于小数点后的乘数是向左移，小数点前的乘数是往右移位。

-The longest sentence, find the sum of the assignment statement is the calculation of the FIR filter, the binary multiplication into shift operation. Multiplier after the decimal point to the left, in front of the decimal point multiplier is shifted to the right.