kbd.c

   1 #include "kbd.h"
   2 #include "console.h"
   3 #include "io.h"
   4
   5 #define KBD_DATA 0x60
   6 #define KBD_STATUS 0x64
   7
   8 #define KBD_BUF_SIZE 16
   9 static int kbd_buf[KBD_BUF_SIZE];
  10 static int kbd_buf_head, kbd_buf_tail;
  11
  12 void kbd_cmd(unsigned char cmd)
  13 {
  14     while (inb(KBD_STATUS) & 0x2);
  15     outb(KBD_DATA, cmd);
  16
  17     while ((inb(KBD_STATUS) & 0x1) == 0);
  18     inb(KBD_DATA);
  19 }
  20
  21 void kbd_init(void)
  22 {
  23     while (inb(KBD_STATUS) & 0x1) {
  24         inb(KBD_DATA);
  25     }
  26
  27     kbd_cmd(0xf4);
  28 }
  29
  30 static void kbd_queue_key(int scancode)
  31 {
  32     if ((kbd_buf_head + 1) % KBD_BUF_SIZE == kbd_buf_tail) {
  33         /* Buffer full, ignore keypress */
  34         return;
  35     }
  36
  37     kbd_buf[kbd_buf_head] = scancode;
  38     kbd_buf_head = (kbd_buf_head + 1) % KBD_BUF_SIZE;
  39 }
  40
  41 int kbd_wait_key(void)
  42 {
  43     int ret;
  44
  45     while (kbd_buf_head == kbd_buf_tail) {
  46         asm volatile("hlt");
  47     }
  48
  49     ret = kbd_buf[kbd_buf_tail];
  50     kbd_buf_tail = (kbd_buf_tail + 1) % KBD_BUF_SIZE;
  51     return ret;
  52 }
  53
  54 void kbd_intr(void)
  55 {
  56     static enum {
  57         KBD_STATE_NORMAL,
  58         KBD_STATE_E0,
  59     } kbd_state = KBD_STATE_NORMAL;
  60
  61     int scancode = inb(KBD_DATA);
  62
  63     switch (kbd_state) {
  64         case KBD_STATE_NORMAL:
  65             if (scancode == 0xe0) {
  66                 kbd_state = KBD_STATE_E0;
  67                 return;
  68             }
  69             if (scancode & 0x80) {
  70                 /* Ignore break codes */
  71                 return;
  72             }
  73             kbd_queue_key(scancode);
  74             break;
  75
  76         case KBD_STATE_E0:
  77             kbd_state = KBD_STATE_NORMAL;
  78             if (scancode & 0x80) {
  79                 /* Ignore break codes */
  80                 return;
  81             }
  82             kbd_queue_key(0x100 | scancode);
  83             break;
  84     }
  85 }