diff options
Diffstat (limited to 'watch-library/watch/watch_utility.c')
| -rw-r--r-- | watch-library/watch/watch_utility.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/watch-library/watch/watch_utility.c b/watch-library/watch/watch_utility.c new file mode 100644 index 00000000..a0f361b4 --- /dev/null +++ b/watch-library/watch/watch_utility.c @@ -0,0 +1,35 @@ +/* + * MIT License + * + * Copyright (c) 2021 Joey Castillo + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in all + * copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include "watch_utility.h" + +const char * watch_utility_get_weekday(watch_date_time date_time) { + static const char weekdays[7][3] = {"SA", "SU", "MO", "TU", "WE", "TH", "FR"}; + date_time.unit.year += 20; + if (date_time.unit.month <= 2) { + date_time.unit.month += 12; + date_time.unit.year--; + } + return weekdays[(date_time.unit.day + 13 * (date_time.unit.month + 1) / 5 + date_time.unit.year + date_time.unit.year / 4 + 525) % 7]; +} |