kbd.c

从网上下载的一个自己编写的简单的操作系统源代码,对底层了解很有好处的

#include <arch.h>




void kb_wait();
void kb_readall();
void kb_write(unsigned char val);



unsigned char readchar()
{
  //dead loop (because origin is if(da&1) )
  unsigned char data,da;
  wait:
  da =inb(0x64); // read , 8042 status
  if(!(da&1)) 
     goto wait; //没有数据,等待 (kbd to host)

  
  data = inb_p(0x60);
 
  return data;
  
}


void kb_write(unsigned char val)
{
   unsigned char da;

   wait:
   da =inb(0x64); // read , 8042 status
   if(da&2) //输出缓冲区满 ( host to kbd )
     goto wait;
   outb(0x60, val);
}



int kb_reset()
{
  int iwait =3000;
    
  kb_wait();
  outb(0x64,0xaa);
  while(readchar()!= 0x55&&iwait--);

  if(iwait==-1)return 0;

  return 1;
   
}

void kb_readall()
{
   unsigned char data;
   unsigned char da;

   

   wait:
   	da =inb(0x64); // read , 8042 status
   if(da&2) //输出缓冲区满 (kbd to host)
     goto read;

   return;

   read:
   data = inb(0x60); //port 0x60 ,data
    goto wait; 
}

////////////////////////////////////////////////////////////////
//下面的开启键盘leds的方法引起计算机重启, why