第十六周课堂测试补充

测试中错误部分的理解和学习

地址的定义部分错误

*(volatile unsigned int *)0x500

(unsigned int *)0x500

0x500

*(unsigned int *)0x500=0x10

0x500

0x10

详见嵌入式中的 (volatile unsigned int )理解

#define DATA_Addr  0xFFFFC0000
#define DATA    *(volatile int *) DATA_Addr

void SetHours(int hours)
{
unsigned short time;
time = (unsigned short)(DATA);
time &= 0x07FF;//将hous小时所在的比特位置0
DATA = ((unsigned short))(hours<<11)|time;//将要设置的hours变量通过移位变换到time变量中hours所在的比特位置，再与time以或运算合并

}
int getHours()
{
unsigned short time;
time = (unsigned short)(DATA);
return (int)((time>>11)&0x001f);//直接将time向右移动11位清除掉分钟和秒的比特位上的数据，再将hours之前的位清零；

}

对于秒部分的提取和置位的学习

#define DATA_Addr  0xFFFFC0000
#define DATA    *(volatile int *) DATA_Addr

void SetSeconds(int seconds)
{
unsigned short time;
time = (unsigned short)(DATA);
time &= 0xffe0;
DATA = ((unsigned short))(seconds)|time;

}
int getSeconds()
{
unsigned short time;
time = (unsigned short)(DATA);
return (int)(time&0x001f);

}