auri.ee
keyboard stuff
1/* Copyright 2021 QMK
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 "utf8.h"
18
19// Borrowed from https://nullprogram.com/blog/2017/10/06/
20const char *decode_utf8(const char *str, int32_t *code_point) {
21 const char *next;
22
23 if (str[0] < 0x80) { // U+0000-007F
24 *code_point = str[0];
25 next = str + 1;
26 } else if ((str[0] & 0xE0) == 0xC0) { // U+0080-07FF
27 *code_point = ((int32_t)(str[0] & 0x1F) << 6) | ((int32_t)(str[1] & 0x3F) << 0);
28 next = str + 2;
29 } else if ((str[0] & 0xF0) == 0xE0) { // U+0800-FFFF
30 *code_point = ((int32_t)(str[0] & 0x0F) << 12) | ((int32_t)(str[1] & 0x3F) << 6) | ((int32_t)(str[2] & 0x3F) << 0);
31 next = str + 3;
32 } else if ((str[0] & 0xF8) == 0xF0 && (str[0] <= 0xF4)) { // U+10000-10FFFF
33 *code_point = ((int32_t)(str[0] & 0x07) << 18) | ((int32_t)(str[1] & 0x3F) << 12) | ((int32_t)(str[2] & 0x3F) << 6) | ((int32_t)(str[3] & 0x3F) << 0);
34 next = str + 4;
35 } else {
36 *code_point = -1;
37 next = str + 1;
38 }
39
40 // part of a UTF-16 surrogate pair - invalid
41 if (*code_point >= 0xD800 && *code_point <= 0xDFFF) {
42 *code_point = -1;
43 }
44
45 return next;
46}