U0 PutKey(I64 ch=0, I64 sc=0)
{//See Keyboard Devices.
    CKeyDevEntry *tmpk;

    if (ch || sc)
    {
        tmpk = keydev.put_key_head.next;
        if (!Bt(&Fs->display_flags, DISPLAYf_SILENT))
        {
            if (kbd.scan_code & SCF_SCROLL && sys_focus_task == Fs)
                while (kbd.scan_code & SCF_SCROLL)
                    Yield; //Wait on SCROLL LOCK Key
            while (tmpk != &keydev.put_key_head)
            {
                if ((!(sc & SCF_KEY_DESC) || tmpk->flags & KDF_HAS_DESCS) && (*tmpk->put_key)(ch, sc))
                    break;
                tmpk = tmpk->next;
            }
        }
    }
}

U0 PutChars(U64 ch)
{//Output chars. Up to 8 chars in a single U64.
//Don't use this.  See Print() shortcut.
    while (ch)
    {
        PutKey(ch & 255, 0);
        ch >>= 8;
    }
}

U0 PutS(U8 *st)
{//Use Print(). See Keyboard Devices.
//Don't use this.  See Print() shortcut.
    I64              ch;
    U8              *ptr;
    Bool             cont = TRUE;
    if (!st) return;
    CKeyDevEntry    *tmpk = keydev.put_key_head.next;

    if (!Bt(&Fs->display_flags, DISPLAYf_SILENT))
    {
        if (kbd.scan_code & SCF_SCROLL && sys_focus_task == Fs)
            while (kbd.scan_code & SCF_SCROLL)
                Yield;
        while (cont && tmpk != &keydev.put_key_head)
        {
            if (tmpk->put_s)
            {
                if ((*tmpk->put_s)(st))
                    break;
            }
            else
            {
                ptr = st;
                while (ch = *ptr++)
                    if ((*tmpk->put_key)(ch, 0))
                        cont = FALSE;
            }
            tmpk = tmpk->next;
        }
    }
}

U0 KeyDescSet(U8 *format, ...)
{//Call this from key handler to report description in KeyMap().
    U8 *buf = StrPrintJoin(NULL, format, argc, argv);

    StrCopy(keydev.desc, buf);
    keydev.handler = Caller;
    Free(buf);
}

U0 KeyDevRemove(CKeyDevEntry *tmpk)
{//Remove StdOut hook and free.
    QueueRemove(tmpk);
    Free(tmpk);
}

CKeyDevEntry *KeyDevAdd(Bool (*fp_put_key)(I64 ch, I64 sc), Bool (*fp_puts)(U8 *st), I64 priority, Bool key_descs=FALSE)
{//Places hook in StdOut chain. See Keyboard Devices.
    CKeyDevEntry *tmpk = keydev.put_key_head.last, *tmpk1 = SysCAlloc(sizeof(CKeyDevEntry));

    tmpk1->put_key  = fp_put_key;
    tmpk1->put_s    = fp_puts;
    tmpk1->priority = priority;
    if (key_descs)
        tmpk1->flags |= KDF_HAS_DESCS;
    while (tmpk->priority > priority)
        tmpk = tmpk->last;
    QueueInsert(tmpk1, tmpk);
    if (tmpk->priority == priority)
        KeyDevRemove(tmpk);

    return tmpk1;
}

Bool KDRawPutKey(I64 ch, I64)
{
    if (IsRaw)
    {
        RawPutChar(ch);
        return TRUE;
    }
    else
        return FALSE;
}

Bool KDRawPutS(U8 *st)
{
    I64 ch;

    if (IsRaw)
    {
        while (ch = *st++)
            RawPutChar(ch);
        return TRUE;
    }
    else
        return FALSE;
}

Bool KDInputFilterPutKey(I64 ch, I64 scan_code)
{
    if (Bt(&Fs->task_flags, TASKf_INPUT_FILTER_TASK))
    {
        Message(MESSAGE_KEY_DOWN, ch, scan_code);
        return TRUE;
    }
    else
        return FALSE;
}

Bool KDInputFilterPutS(U8 *st)
{
    I64 ch;

    if (Bt(&Fs->task_flags, TASKf_INPUT_FILTER_TASK))
    {
        while (ch = *st++)
            Message(MESSAGE_KEY_DOWN, ch, 0);
        return TRUE;
    }
    else
        return FALSE;
}

U0 CtrlAltDel(I64)
{
    LBts(sys_ctrl_alt_flags, CTRL_ALT_DEL);
}

U0 CtrlAltC(I64)
{
    LBts(sys_ctrl_alt_flags, CTRL_ALT_C);
}

U0 CtrlAltD(I64)
{
    if (!IsDebugMode)
    {
        if (Fs == Gs->idle_task)
            BptS(sys_winmgr_task->rip, sys_winmgr_task);
        else
            BptS(*keydev.ctrl_alt_ret_addr);
    }
}

U0 CtrlAltF(I64)
{
    SwapI64(&text.font, &text.aux_font);
}

U0 CtrlAltM(I64)
{
    Mute(!IsMute);
}

U0 CtrlAltN(I64)
{
    LBts(sys_ctrl_alt_flags, CTRL_ALT_TAB);
}

U0 CtrlAltT(I64)
{
    User;
}

U0 CtrlAltV(I64)
{
    LFBFlush;
    text.is_fb_busy = FALSE;
}

U0 CtrlAltX(I64)
{
    LBts(sys_ctrl_alt_flags, CTRL_ALT_X);
}

U0 CtrlAltCBSet(U8 ch, U0 (*fp_handler)(I64 sc), U8 *no_shift_desc=NULL, U8 *shift_desc=NULL, Bool in_irq=FALSE)
{//Set callback for <CTRL-ALT-letter>.
    ch = ToUpper(ch) - 'A';
    if (ch < 26)
    {
        keydev.fp_ctrl_alt_cbs[ch] = fp_handler;

        Free(keydev.ctrl_alt_no_shift_descs[ch]);
        if (no_shift_desc)
            keydev.ctrl_alt_no_shift_descs[ch] = SysStrNew(no_shift_desc);
        else
            keydev.ctrl_alt_no_shift_descs[ch] = NULL;

        Free(keydev.ctrl_alt_shift_descs[ch]);
        if (shift_desc)
            keydev.ctrl_alt_shift_descs[ch] = SysStrNew(shift_desc);
        else
            keydev.ctrl_alt_shift_descs[ch] = NULL;

        BEqual(&keydev.ctrl_alt_in_irq_flags, ch, in_irq);
    }
}

U0 KeyDevInit()
{
    keydev.fp_ctrl_alt_cbs          = CAlloc(26 * sizeof(U8 *));
    keydev.ctrl_alt_no_shift_descs  = CAlloc(26 * sizeof(U8 *));
    keydev.ctrl_alt_shift_descs     = CAlloc(26 * sizeof(U8 *));
    keydev.ctrl_alt_in_irq_flags    = 0;
    MemSet(&keydev.put_key_head, 0, sizeof(CKeyDevEntry));
    QueueInit(&keydev.put_key_head);
    KeyDevAdd(&KDInputFilterPutKey, &KDInputFilterPutS, 0x40000000, FALSE);
    KeyDevAdd(&KDRawPutKey, &KDRawPutS, 0x60000000, FALSE);
    CtrlAltCBSet('C', &CtrlAltC, "Cmd /Break Execution",, TRUE);
    CtrlAltCBSet('D', &CtrlAltD, "Cmd /Enter Debugger",, TRUE);
    CtrlAltCBSet('F', &CtrlAltF, "Cmd /Toggle Aux Font");
    CtrlAltCBSet('M', &CtrlAltM, "Cmd /Toggle Mute");
    CtrlAltCBSet('N', &CtrlAltN, "Cmd /Next Focus Task",, TRUE);
    CtrlAltCBSet('T', &CtrlAltT, "Cmd /Terminal Window");
    CtrlAltCBSet('V', &CtrlAltV, "Cmd /Video Framebuffer Flush",, TRUE);
    CtrlAltCBSet('X', &CtrlAltX, "Cmd /Kill Focused Task",, TRUE);
}