// PC keyboard interface constants
//
// The scancode tables themselves are no longer here. They moved to
// kernel/dev/keymap.c when there became more than one of them -- a header
// full of `static` arrays gives every file that includes it its own private
// copy, which was harmless while exactly one file did.

#ifndef KBD_H
#define KBD_H

#define KBSTATP         0x64    // kbd controller status port(I)
#define KBS_DIB         0x01    // kbd data in buffer
#define KBDATAP         0x60    // kbd data port(I)

#define NO              0

#define SHIFT           (1<<0)
#define CTL             (1<<1)
#define ALT             (1<<2)

#define CAPSLOCK        (1<<3)
#define NUMLOCK         (1<<4)
#define SCROLLLOCK      (1<<5)

#define E0ESC           (1<<6)

// Right Alt, tracked apart from left Alt.
//
// They used to be the same bit, which is fine for typing -- neither is used to
// look up a character -- and wrong for chords. On a Polish layout AltGr is how
// you type a c e l n o s x z with their diacritics, and it is held constantly.
// Nothing the kernel binds may involve it.
#define RALT            (1<<7)

// Special keycodes.
//
// **Above every Unicode codepoint, deliberately**, and they did not use to be:
// KBD_UP was 0xE2 and its neighbours filled 0xE0..0xE9. Those are exactly the
// UTF-8 lead bytes for three-byte characters, so typing any of U+0800..U+FFFF
// -- which is most punctuation, every arrow, every maths symbol, and the whole
// of CJK -- produced a keycode the console read as an arrow key and turned
// into `ESC [ A`. `∞`, `→`, `≤` and `'` all vanished from the input line while
// `ą` and `ę` came through, because those are two-byte sequences whose lead
// byte is 0xC4 and nothing claimed 0xC4.
//
// The chord codes below already knew this rule and said so; the navigation
// keys predate them and were never brought in line. The rule, stated once: a
// value that a key produces is either a Unicode codepoint or it is above
// 0x10FFFF, and nothing in between means anything.
#define KBD_SPECIAL     0x110000

#define KBD_HOME        (KBD_SPECIAL + 0x00)
#define KBD_END         (KBD_SPECIAL + 0x01)
#define KBD_UP          (KBD_SPECIAL + 0x02)
#define KBD_DN          (KBD_SPECIAL + 0x03)
#define KBD_LF          (KBD_SPECIAL + 0x04)
#define KBD_RT          (KBD_SPECIAL + 0x05)
#define KBD_PGUP        (KBD_SPECIAL + 0x06)
#define KBD_PGDN        (KBD_SPECIAL + 0x07)
#define KBD_INS         (KBD_SPECIAL + 0x08)
#define KBD_DEL         (KBD_SPECIAL + 0x09)
// F1..F12, consecutive: KBD_F1 + n is F(n+1).
#define KBD_F1          (KBD_SPECIAL + 0x10)
#define KBD_F12         (KBD_SPECIAL + 0x1B)

// Switch virtual terminal.
//
// *Which* chord is a runtime setting, not a constant here, and that is the
// interesting part. Three separate parties have a claim on every candidate:
//
//   the HOST, which sees the keystroke first and may never pass it on
//     Alt+F4, Alt+F2            window manager
//     Ctrl+Alt+F1..F6           display manager, and it matches loosely --
//                               adding Shift does not get past it
//     Ctrl+Alt+<digit>          QEMU's own console tabs
//
//   APPLICATIONS, which lose the key permanently if the kernel eats it
//     Alt+<anything>            Meta. zsh binds Meta-digit as digit-argument
//     Ctrl+<letter>             control characters
//     Ctrl+Shift+<digit>        types a character -- Ctrl+Shift+2 is ^@
//     F1..F6 alone              help, and full-screen programs
//
//   the KEYBOARD LAYOUT
//     AltGr+<letter>            Polish diacritics, and on some setups AltGr
//                               arrives as Ctrl+Alt
//
// There is no combination that is free for everyone on every host, and the
// guest cannot find out what its host grabs -- the keystroke simply never
// arrives, which is indistinguishable from a chord nobody pressed. So the
// kernel ships a default and lets it be changed: VT_SETCHORD, and `chvt -c`
// in userspace. Setting it to no modifiers disables the chord entirely and
// leaves `chvt N` as the only way to switch, which is a legitimate choice on
// a machine whose host takes everything.
//
// The default is Ctrl+Alt+F1..F12: the keys X switches with, so the console
// and the desktop answer the same chord. It used to be AltGr+F-key, which
// nothing else claims -- Right Alt being a separate modifier bit here is what
// makes that expressible, and `chvt -c altgr+F` still sets it.
#define KBD_VT_SWITCH   (KBD_SPECIAL + 0x20)

// Previous / next terminal, on the same modifiers as the chord above. The
// minus and equals keys, which sit together and read as - and + -- a relative
// move for when you have two terminals and do not care which number they are.
#define KBD_VT_PREV     (KBD_SPECIAL + 0x30)
#define KBD_VT_NEXT     (KBD_SPECIAL + 0x31)

#define SCAN_MINUS      0x0C      // - / _
#define SCAN_EQUALS     0x0D      // = / +

#define SCAN_F1         0x3B      // F1..F6 are scancodes 0x3B..0x40
#define SCAN_1          0x02      // 1..6 are scancodes 0x02..0x07

// C('A') == Control-A
#define C(x) (x - '@')

#endif /* KBD_H */