求大神指导不懂如何画出来的。求解释。。

uchar i;
uchar xdata y_sin[128]; //定义屏幕上要打的正弦波的纵坐标
uchar code v[128]={32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,
32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,
32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,
32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,};
float y;
for(i=0;i<128;i++)
{
y=31*sin(0.09*i)+0.5; //此处系数为31比较好
y_sin[i]=32-y;
}
for(i=0;i<64;i++)
LCD_draw_word(y_sin, i); //绘图 一行一行绘
LCD_draw_word(v, 32);