OSDev.org

Code: Select all

volatile shift_locks shifts;
volatile unsigned int keycount=0;
volatile unsigned char keys[128];

unsigned char get_kbd_buffer(unsigned char *scan_buf,unsigned char *asc_buf){
   keycount--;
     *scan_buf=keys[keycount];
   keycount--;
   *asc_buf=keys[keycount];
   return *asc_buf;
}


char getkey(char *buf){ 
   //char tmp[1]; error! allocated on stack
   
   while(keycount==0){}
   get_kbd_buffer(&buf[0],&buf[1]);
   return buf[1];
}

void waitkey(){
   char tmp[1];
   while(keycount==0){}
   get_kbd_buffer(&tmp[0],&tmp[1]);
}

/*F6-F10 are reserved for window functions and are not useable in applications*/
extern int TextUI;
extern WINDOW mcon;
void kbd_handler(r){
   unsigned char scancode;unsigned char tmp;
   if (keycount==128){return 0;}
     scancode = inportb(0x60);
     if (scancode & 0x80) { //this i thought meant that the key was released
          switch (scancode) {
               case 42|0x80:
               shifts.shift=0;
               break;
               case 54|0x80:
               shifts.shift=0;
               break;
               case 29|0x80:
               shifts.ctrl=0;
               break;
               case 56|0x80:
               shifts.alt=0;
               break;
          }
     }else{

     switch (scancode){
        case 42: 
        shifts.shift=1;
        break;
        case 54:
        shifts.shift=1;
        break;
        case 29:
        shifts.ctrl=1;
        break;
        case 56:
          shifts.alt=1;
          break;
          case 58:
          shifts.caps=shifts.caps ^ 1;
          break;
          case 69:
          shifts.num=shifts.num ^ 1;
          break;
          case 70:
          shifts.scroll=shifts.scroll ^ 1;
          break;
          
     }
     if (TextUI==1){
        switch(scancode){
           case 0x40:
           cwin=def_console;
           break;
           case 0x41:
           cwin=&mcon;
           break;
           case 0x42:
           
           break;
           case 0x43:
           
           break;
           case 0x44:
           
           break;
        }
     }
          
     tmp=scan2asc(scancode);
     put_kbd_buffer(scancode,tmp);


     }
     
}

Code: Select all

void kbd_interrupt()
{
   //our new Keyboard Interrupt
   unsigned char kbd_ascii_code=0;
   
   disable(); //Let an interrupt not interrupt another
   kbd_scancode = inportb(0x60);
   outportb(0x20,0x20); //Acknowledge it
   kbd_shift=0,kbd_caps=0;
   if(1/*!kbd_special(kbd_scancode)*/)
   {
      if(kbd_shift)
      {
         if(!kbd_caps)
            kbd_ascii_code = kbd_shifted[kbd_scancode];
         else
            kbd_ascii_code = kbd_caps_shifted[kbd_scancode];
      }
      else 
      {
         if(!kbd_caps)
            kbd_ascii_code = kbd_normal[kbd_scancode];
         else
            kbd_ascii_code = kbd_capsnormal[kbd_scancode];
      }
      
      if(kbd_buffer_pos != eob)
         kbd_buffer[kbd_buffer_pos++]=kbd_ascii_code;
      else
      {
         kbd_buffer[kbd_buffer_pos]  =kbd_ascii_code;
         kbd_buffer_pos=0;
      }
   }
   outportb(0x20,0x20);
   enable();
   kbd_flush_buffer(); //flush
   interrupted = 1;
}      

unsigned char kbd_getch()      // Waits for a key to enter the buffer and returns it
{
   int i = 0;
   //print((unsigned char *)"I am here");
   loop:
   if(interrupted == 0) goto loop;
   //print((unsigned char *)"Done!");
   interrupted=0;      
         
   disable(); //something in the buffer... Disable all other interrupts
   for(i=0; i < kbd_buffer_pos; i++)
   {
      kbd_buffer[i] = kbd_buffer[i + 1];
   }
   kbd_buffer_pos--; //immediately Shift the buffer back
   enable();
   
   return (unsigned char)kbd_buffer[0];
}

Code: Select all

- interrupt received, kp_buffer_pos == 0.
- decoded keystroke is stored in kb_buffer[0]
- interupted is set to 1, which "unlocks" the "goto loop" (i suppose the reason you're not using "while (!interrupted)" is just that you had trouble with it.
- getch() will now find kb_buffer_pos==1 and will do the "for" loop with i=0
- that means kb_buffer[0] <-- kb_buffer[1];
- and then you return kb_buffer[1] (which is likely to be zero unless you managed to receive two bytes.

Code: Select all

loc_sme number:
mov eax,ds:[some address of the kbd_buffer_pos]
cmp eax,0 ;or some equivalent of this.
je loc_sme number

Code: Select all

cmp eax,1

Code: Select all

test eax,eax