static void
dequeue_key(struct bregs *regs, int incr, int extended)
{
yield();
u16 buffer_head;
u16 buffer_tail;
for (;;) {
buffer_head = GET_BDA(kbd_buf_head);
buffer_tail = GET_BDA(kbd_buf_tail);
if (buffer_head != buffer_tail)
break;
if (!incr) {
regs->flags |= F_ZF;
return;
}
yield_toirq();
}
u16 keycode = GET_FARVAR(SEG_BDA, *(u16*)(buffer_head+0));
u8 ascii = keycode & 0xff;
if (!extended) {
// Translate extended keys
if (ascii == 0xe0 && keycode & 0xff00)
keycode &= 0xff00;
else if (keycode == 0xe00d || keycode == 0xe00a)
// Extended enter key
keycode = 0x1c00 | ascii;
else if (keycode == 0xe02f)
// Extended '/' key
keycode = 0x352f;
// Technically, if the ascii value is 0xf0 or if the
// 'scancode' is greater than 0x84 then the key should be
// discarded. However, there seems no harm in passing on the
// extended values in these cases.
}
if (ascii == 0xf0 && keycode & 0xff00)
keycode &= 0xff00;
regs->ax = keycode;
if (!incr) {
regs->flags &= ~F_ZF;
return;
}
u16 buffer_start = GET_BDA(kbd_buf_start_offset);
u16 buffer_end = GET_BDA(kbd_buf_end_offset);
buffer_head += 2;
if (buffer_head >= buffer_end)
buffer_head = buffer_start;
SET_BDA(kbd_buf_head, buffer_head);
}
static void
dequeue_key(struct bregs *regs, int incr, int extended)
{
yield();
u16 buffer_head;
u16 buffer_tail;
for (;;) {
buffer_head = GET_BDA(kbd_buf_head);
buffer_tail = GET_BDA(kbd_buf_tail);
if (buffer_head != buffer_tail)
break;
if (!incr) {
regs->flags |= F_ZF;
return;
}
yield_toirq();
}
u8 ascii_code = GET_FARVAR(SEG_BDA, *(u8*)(buffer_head+0));
u8 scan_code = GET_FARVAR(SEG_BDA, *(u8*)(buffer_head+1));
if ((ascii_code == 0xF0 && scan_code != 0)
|| (ascii_code == 0xE0 && !extended))
ascii_code = 0;
regs->ax = (scan_code << 8) | ascii_code;
if (!incr) {
regs->flags &= ~F_ZF;
return;
}
u16 buffer_start = GET_BDA(kbd_buf_start_offset);
u16 buffer_end = GET_BDA(kbd_buf_end_offset);
buffer_head += 2;
if (buffer_head >= buffer_end)
buffer_head = buffer_start;
SET_BDA(kbd_buf_head, buffer_head);
}