diff options
| -rw-r--r-- | src/fsm/common.c | 17 | ||||
| -rw-r--r-- | src/fsm/common.h | 9 |
2 files changed, 26 insertions, 0 deletions
diff --git a/src/fsm/common.c b/src/fsm/common.c index ca4c009..517eb80 100644 --- a/src/fsm/common.c +++ b/src/fsm/common.c @@ -26,6 +26,7 @@ #include "FreeRTOS.h" #include "timers.h" #include <stm32f4xx.h> +#include <time.h> static uint64_t common_timestamp = 0; // milliseconds since startup static TimerHandle_t common_timer; @@ -60,6 +61,22 @@ uint64_t timestamp_now(void) return common_timestamp; } +int dayofweek(uint8_t day, uint8_t month, uint16_t year) +{ + /* Zeller's congruence for the Gregorian calendar. + * With 0=Monday, ... 5=Saturday, 6=Sunday + */ + if (month < 3) { + month += 12; + year--; + } + int k = year % 100; + int j = year / 100; + int h = day + 13*(month+1)/5 + k + k/4 + j/4 + 5*j; + return (h + 5) % 7 + 1; +} + + // Return either 0 or 1, somewhat randomly int random_bool(void) { diff --git a/src/fsm/common.h b/src/fsm/common.h index b33f1f8..a2d20ab 100644 --- a/src/fsm/common.h +++ b/src/fsm/common.h @@ -37,6 +37,15 @@ void common_init(void); // wall clock time. uint64_t timestamp_now(void); +/* Convert date to day of week. + * day: 1-31 + * month: 1-12 + * year: 1900 to 3000 + * + * Returns 1=Monday, ... 6=Saturday, 7=Sunday + */ +int dayofweek(uint8_t day, uint8_t month, uint16_t year); + // Return either 0 or 1, somewhat randomly int random_bool(void); |