File time.c

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/* Copyright (c) Kuba Szczodrzyński 2022-09-03. */

#include <Arduino.h>
#include <errno.h>

static uint32_t reset_epoch  = 0; // epoch corresponding to millis() == 0
static uint32_t reset_millis = 0; // millis() when epoch reset was performed

int __wrap_gettimeofday(struct timeval *tv, void *tz) {
    if (millis() < reset_millis) {
        // the clock overflowed
        reset_epoch += UINT32_MAX / 1000;
        reset_millis = millis();
    }
    if (!tv) {
        errno = EINVAL;
        return -1;
    }
    unsigned long m = millis();
    tv->tv_sec      = reset_epoch + (m / 1000);
    tv->tv_usec     = (m % 1000) * 1000;
    return 0;
}

int __wrap_settimeofday(const struct timeval *tv, const struct timezone *tz) {
    if (!tv) {
        errno = EINVAL;
        return -1;
    }
    unsigned long m = millis();
    reset_epoch     = tv->tv_sec - (m / 1000);
    reset_millis    = m;
    return 0;
}

int gettimeofday(struct timeval *tv, void *tz) {
    return __wrap_gettimeofday(tv, tz);
}

int settimeofday(const struct timeval *tv, const struct timezone *tz) {
    return __wrap_settimeofday(tv, tz);
}

int _gettimeofday(struct timeval *tv, void *tz) {
    return __wrap_gettimeofday(tv, tz);
}

int _settimeofday(const struct timeval *tv, const struct timezone *tz) {
    return __wrap_settimeofday(tv, tz);
}