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adding some comments

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Gered 2018-05-27 13:15:58 -04:00
parent 048fd83331
commit fc44d4de73
1 changed files with 27 additions and 7 deletions
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34
DGLKBRD.C
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@ -216,6 +216,8 @@ static void push_keyboard_event(KEY key, EVENT_ACTION action) {
}
}
// returns TRUE if the key interrupt event should not be handled (at least
// as far as updating key state is concerned)
static boolean handler_filter_keys(void) {
if (BIT_ISSET(KEYBRD_MOD_EXTENDED, key_mod)) {
// extended key + leftshift comes with cursor key presses when
@ -226,6 +228,7 @@ static boolean handler_filter_keys(void) {
return FALSE;
}
// maintains BIOS keyboard flags/led toggle states (caps/num/scroll lock)
static void handler_update_flags_and_leds(void) {
switch (_key_scan) {
case (KEY)KEY_CAPSLOCK:
@ -248,6 +251,7 @@ static void handler_update_flags_and_leds(void) {
}
}
// updates modifier state based on current BIOS flags and/or key states
static void handler_update_modifiers(void) {
if (BIT_ISSET(KEYBRD_FLAGS_NUMLOCK, key_flags))
BIT_SET(KEYBRD_MOD_NUMLOCK, key_mod);
@ -266,13 +270,24 @@ static void handler_update_modifiers(void) {
}
// keyboard interrupt handler
// TODO: handle 'Pause' key... it's kind of a weird one and this all doesn't
// take care of it at all.
// also, i suspect this may all have issues with international keyboards
// but i don't own any so cannot test...
void interrupt far kb_int_handler(void) {
// read scan code of key that was just pressed
_key_scan = inp(KEYBRD_DATA_PORT);
if (_key_scan == KEY_EXTENDED) {
// extended key scan
BIT_SET(KEYBRD_MOD_EXTENDED, key_mod);
// handle updating key state and flags/modifiers ...
if (_key_scan == KEY_EXTENDED) {
// "extended key" events come in as two events to this interrupt
// handler. the first has _key_scan = 0xe0 (0x60 in a released state).
// so we catch this "weird" _key_scan value and set the extended
// modifier here and skip updating any other keyboard state.
// for the key event that will follow immediately after this, _key_scan
// will have the _actual_ key that was pressed, but the modifier will
// be set correctly and we can handle it specially if needed.
BIT_SET(KEYBRD_MOD_EXTENDED, key_mod);
} else {
if (!handler_filter_keys()) {
if (_key_scan & 0x80) {
@ -283,10 +298,12 @@ void interrupt far kb_int_handler(void) {
handler_update_modifiers();
push_keyboard_event(_key_scan, EVENT_ACTION_RELEASED);
} else {
if (keys[(int)_key_scan])
if (keys[(int)_key_scan]) {
// nothing interesting to do for held (repeat) events...
push_keyboard_event(_key_scan, EVENT_ACTION_HELD);
else {
} else {
keys[(int)_key_scan] = 1;
// toggle states only need to be handled for a down event
handler_update_flags_and_leds();
handler_update_modifiers();
push_keyboard_event(_key_scan, EVENT_ACTION_PRESSED);
@ -295,6 +312,7 @@ void interrupt far kb_int_handler(void) {
_key_last_scan = _key_scan;
}
// clear extended modifier for the following event(s) in any case
BIT_CLEAR(KEYBRD_MOD_EXTENDED, key_mod);
}
@ -356,12 +374,12 @@ char key_to_char(KEY key, uword modifiers) {
if (BIT_ISSET(KEYBRD_MOD_EXTENDED, modifiers)) {
return lookup_key_to_char_extended[(int)key];
}
else if ((key >= (KEY)0x47) && (key <= (KEY)0x53)) {
if (BIT_ISSET(KEYBRD_MOD_NUMLOCK, modifiers) &&
!BIT_ISSET(KEYBRD_MOD_SHIFT, modifiers))
return lookup_key_to_char_numpad[(int)key];
else
return 0;
} else {
if (BIT_ISSET(KEYBRD_MOD_CAPSLOCK, modifiers)) {
if (BIT_ISSET(KEYBRD_MOD_SHIFT, modifiers))
@ -375,5 +393,7 @@ char key_to_char(KEY key, uword modifiers) {
return lookup_key_to_char[(int)key];
}
}
return 0;
}