读书笔记《30天自制操作系统》day07

http://blog.csdn.net/ltbylc/article/details/8309257

1. 键盘中断的处理：产生中断后中断处理程序应该向PIC发出OCW2发出0x60+IRQ号码的out指令，并发出in指令从0x0060读取键盘信息，该键盘信息保存到FIFO缓冲区中。

#define PORT_KEYDATA 0x0060
struct FIFO8 keyfifo;
void inthandler21(int* esp)
{
    unsigned char data;
    io_out8(PIC0_OCW2,0x61);
    data=io_in8(PORT_KEYDATA);
    fifo8_put(&keyfifo,data);
    return ;
}

 

2. 主程序在没事干的时候即执行HLT循环时查看缓冲区有无数据，有则取出显示

/* in MariMain*/
char s[40],mcursor[256],keybuf[32];
fifo8_init(&keyfifo,32,keybuf);
for(;;)
{
    io_cli();
    if(fifo8_status(&keyfifo)==0)
    {
        io_stihlt();
    }
   else
    {
        i=fifo8_get(&keyfifo);
        io_sti();
        /*显示i值*/
    }
}

3. FIFO缓冲区，能有效处理Ctrl键的问题

 

#define FLAGS_OVERRUN       0x0001

void fifo8_init(struct FIFO8 *fifo, int size, unsigned char *buf)
{
    fifo->size = size;
    fifo->buf = buf;
    fifo->free = size;
    fifo->flags = 0;
    fifo->p = 0;
    fifo->q = 0;
    return;
}

int fifo8_put(struct FIFO8 *fifo, unsigned char data)
{
    if (fifo->free == 0) {

        fifo->flags |= FLAGS_OVERRUN;
        return -1;
    }
    fifo->buf[fifo->p] = data;
    fifo->p++;
    if (fifo->p == fifo->size) {
        fifo->p = 0;
    }
    fifo->free--;
    return 0;
}

int fifo8_get(struct FIFO8 *fifo)
{
    int data;
    if (fifo->free == fifo->size) {
        return -1;
    }
    data = fifo->buf[fifo->q];
    fifo->q++;
    if (fifo->q == fifo->size) {
        fifo->q = 0;
    }
    fifo->free++;
    return data;
}

int fifo8_status(struct FIFO8 *fifo)
{
    return fifo->size - fifo->free;
}