process_key_lock.c
6599 bytes
1/* Copyright 2017 Fredric Silberberg
2 *
3 * This program is free software: you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation, either version 2 of the License, or
6 * (at your option) any later version.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program. If not, see <http://www.gnu.org/licenses/>.
15 */
16
17#include <inttypes.h>
18#include <stdint.h>
19#include "process_key_lock.h"
20
21#define BV_64(shift) (((uint64_t)1) << (shift))
22#define GET_KEY_ARRAY(code) (((code) < 0x40) ? key_state[0] : ((code) < 0x80) ? key_state[1] : ((code) < 0xC0) ? key_state[2] : key_state[3])
23#define GET_CODE_INDEX(code) (((code) < 0x40) ? (code) : ((code) < 0x80) ? (code)-0x40 : ((code) < 0xC0) ? (code)-0x80 : (code)-0xC0)
24#define KEY_STATE(code) (GET_KEY_ARRAY(code) & BV_64(GET_CODE_INDEX(code))) == BV_64(GET_CODE_INDEX(code))
25#define SET_KEY_ARRAY_STATE(code, val) \
26 do { \
27 switch (code) { \
28 case 0x00 ... 0x3F: \
29 key_state[0] = (val); \
30 break; \
31 case 0x40 ... 0x7F: \
32 key_state[1] = (val); \
33 break; \
34 case 0x80 ... 0xBF: \
35 key_state[2] = (val); \
36 break; \
37 case 0xC0 ... 0xFF: \
38 key_state[3] = (val); \
39 break; \
40 } \
41 } while (0)
42#define SET_KEY_STATE(code) SET_KEY_ARRAY_STATE(code, (GET_KEY_ARRAY(code) | BV_64(GET_CODE_INDEX(code))))
43#define UNSET_KEY_STATE(code) SET_KEY_ARRAY_STATE(code, (GET_KEY_ARRAY(code)) & ~(BV_64(GET_CODE_INDEX(code))))
44#define IS_STANDARD_KEYCODE(code) ((code) <= 0xFF)
45
46// Locked key state. This is an array of 256 bits, one for each of the standard keys supported qmk.
47uint64_t key_state[4] = {0x0, 0x0, 0x0, 0x0};
48bool watching = false;
49
50// Translate any OSM keycodes back to their unmasked versions.
51static inline uint16_t translate_keycode(uint16_t keycode) {
52 if (keycode > QK_ONE_SHOT_MOD && keycode <= QK_ONE_SHOT_MOD_MAX) {
53 return keycode ^ QK_ONE_SHOT_MOD;
54 } else {
55 return keycode;
56 }
57}
58
59void cancel_key_lock(void) {
60 watching = false;
61 UNSET_KEY_STATE(0x0);
62}
63
64bool process_key_lock(uint16_t *keycode, keyrecord_t *record) {
65 // We start by categorizing the keypress event. In the event of a down
66 // event, there are several possibilities:
67 // 1. The key is not being locked, and we are not watching for new keys.
68 // In this case, we bail immediately. This is the common case for down events.
69 // 2. The key was locked, and we need to unlock it. In this case, we will
70 // reset the state in our map and return false. When the user releases the
71 // key, the up event will no longer be masked and the OS will observe the
72 // released key.
73 // 3. QK_LOCK was just pressed. In this case, we set up the state machine
74 // to watch for the next key down event, and finish processing
75 // 4. The keycode is below 0xFF, and we are watching for new keys. In this case,
76 // we will send the key down event to the os, and set the key_state for that
77 // key to mask the up event.
78 // 5. The keycode is above 0xFF, and we're wathing for new keys. In this case,
79 // the user pressed a key that we cannot "lock", as it's a series of keys,
80 // or a macro invocation, or a layer transition, or a custom-defined key, or
81 // or some other arbitrary code. In this case, we bail immediately, reset
82 // our watch state, and return true.
83 //
84 // In the event of an up event, there are these possibilities:
85 // 1. The key is not being locked. In this case, we return true and bail
86 // immediately. This is the common case.
87 // 2. The key is being locked. In this case, we will mask the up event
88 // by returning false, so the OS never sees that the key was released
89 // until the user pressed the key again.
90
91 // We translate any OSM keycodes back to their original keycodes, so that if the key being
92 // one-shot modded is a standard keycode, we can handle it. This is the only set of special
93 // keys that we handle
94 uint16_t translated_keycode = translate_keycode(*keycode);
95
96 if (record->event.pressed) {
97 // Non-standard keycode, reset and return
98 if (!(IS_STANDARD_KEYCODE(translated_keycode) || translated_keycode == QK_LOCK)) {
99 watching = false;
100 return true;
101 }
102
103 // If we're already watching, turn off the watch.
104 if (translated_keycode == QK_LOCK) {
105 watching = !watching;
106 return false;
107 }
108
109 if (IS_STANDARD_KEYCODE(translated_keycode)) {
110 // We check watching first. This is so that in the following scenario, we continue to
111 // hold the key: QK_LOCK, KC_F, QK_LOCK, KC_F
112 // If we checked in reverse order, we'd end up holding the key pressed after the second
113 // KC_F press is registered, when the user likely meant to hold F
114 if (watching) {
115 watching = false;
116 SET_KEY_STATE(translated_keycode);
117 // We need to set the keycode passed in to be the translated keycode, in case we
118 // translated a OSM back to the original keycode.
119 *keycode = translated_keycode;
120 // Let the standard keymap send the keycode down event. The up event will be masked.
121 return true;
122 }
123
124 if (KEY_STATE(translated_keycode)) {
125 UNSET_KEY_STATE(translated_keycode);
126 // The key is already held, stop this process. The up event will be sent when the user
127 // releases the key.
128 return false;
129 }
130 }
131
132 // Either the key isn't a standard key, or we need to send the down event. Continue standard
133 // processing
134 return true;
135 } else {
136 // Stop processing if it's a standard key and we're masking up.
137 return !(IS_STANDARD_KEYCODE(translated_keycode) && KEY_STATE(translated_keycode));
138 }
139}