lib: Move time utility functions to common library.

1 files changed, 211 insertions, 0 deletions

diff --git a/lib/timeutils/timeutils.c b/lib/timeutils/timeutils.c
new file mode 100644
index 0000000000..77e5f043f1
--- /dev/null
+++ b/lib/timeutils/timeutils.c
@@ -0,0 +1,211 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2015 Daniel Campora
+ *
+ * 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 "py/obj.h"
+
+#include "timeutils.h"
+
+// LEAPOCH corresponds to 2000-03-01, which is a mod-400 year, immediately
+// after Feb 29. We calculate seconds as a signed integer relative to that.
+//
+// Our timebase is is relative to 2000-01-01.
+
+#define LEAPOCH ((31 + 29) * 86400)
+
+#define DAYS_PER_400Y (365*400 + 97)
+#define DAYS_PER_100Y (365*100 + 24)
+#define DAYS_PER_4Y   (365*4   + 1)
+
+STATIC const uint16_t days_since_jan1[]= { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
+
+bool timeutils_is_leap_year(mp_uint_t year) {
+    return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
+}
+
+// month is one based
+mp_uint_t timeutils_days_in_month(mp_uint_t year, mp_uint_t month) {
+    mp_uint_t mdays = days_since_jan1[month] - days_since_jan1[month - 1];
+    if (month == 2 && timeutils_is_leap_year(year)) {
+        mdays++;
+    }
+    return mdays;
+}
+
+// compute the day of the year, between 1 and 366
+// month should be between 1 and 12, date should start at 1
+mp_uint_t timeutils_year_day(mp_uint_t year, mp_uint_t month, mp_uint_t date) {
+    mp_uint_t yday = days_since_jan1[month - 1] + date;
+    if (month >= 3 && timeutils_is_leap_year(year)) {
+        yday += 1;
+    }
+    return yday;
+}
+
+void timeutils_seconds_since_2000_to_struct_time(mp_uint_t t, timeutils_struct_time_t *tm) {
+    // The following algorithm was adapted from musl's __secs_to_tm and adapted
+    // for differences in Micro Python's timebase.
+
+    mp_int_t seconds = t - LEAPOCH;
+
+    mp_int_t days = seconds / 86400;
+    seconds %= 86400;
+    tm->tm_hour = seconds / 3600;
+    tm->tm_min = seconds / 60 % 60;
+    tm->tm_sec = seconds % 60;
+
+    mp_int_t wday = (days + 2) % 7;   // Mar 1, 2000 was a Wednesday (2)
+    if (wday < 0) {
+        wday += 7;
+    }
+    tm->tm_wday = wday;
+
+    mp_int_t qc_cycles = days / DAYS_PER_400Y;
+    days %= DAYS_PER_400Y;
+    if (days < 0) {
+        days += DAYS_PER_400Y;
+        qc_cycles--;
+    }
+    mp_int_t c_cycles = days / DAYS_PER_100Y;
+    if (c_cycles == 4) {
+        c_cycles--;
+    }
+    days -= (c_cycles * DAYS_PER_100Y);
+
+    mp_int_t q_cycles = days / DAYS_PER_4Y;
+    if (q_cycles == 25) {
+        q_cycles--;
+    }
+    days -= q_cycles * DAYS_PER_4Y;
+
+    mp_int_t years = days / 365;
+    if (years == 4) {
+        years--;
+    }
+    days -= (years * 365);
+
+    /* We will compute tm_yday at the very end
+    mp_int_t leap = !years && (q_cycles || !c_cycles);
+
+    tm->tm_yday = days + 31 + 28 + leap;
+    if (tm->tm_yday >= 365 + leap) {
+        tm->tm_yday -= 365 + leap;
+    }
+
+    tm->tm_yday++;  // Make one based
+    */
+
+    tm->tm_year = 2000 + years + 4 * q_cycles + 100 * c_cycles + 400 * qc_cycles;
+
+    // Note: days_in_month[0] corresponds to March
+    STATIC const int8_t days_in_month[] = {31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31, 29};
+
+    mp_int_t month;
+    for (month = 0; days_in_month[month] <= days; month++) {
+        days -= days_in_month[month];
+    }
+
+    tm->tm_mon = month + 2;
+    if (tm->tm_mon >= 12) {
+        tm->tm_mon -= 12;
+        tm->tm_year++;
+    }
+    tm->tm_mday = days + 1; // Make one based
+    tm->tm_mon++;   // Make one based
+
+    tm->tm_yday = timeutils_year_day(tm->tm_year, tm->tm_mon, tm->tm_mday);
+}
+
+// returns the number of seconds, as an integer, since 2000-01-01
+mp_uint_t timeutils_seconds_since_2000(mp_uint_t year, mp_uint_t month,
+    mp_uint_t date, mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {
+    return
+        second
+        + minute * 60
+        + hour * 3600
+        + (timeutils_year_day(year, month, date) - 1
+            + ((year - 2000 + 3) / 4) // add a day each 4 years starting with 2001
+            - ((year - 2000 + 99) / 100) // subtract a day each 100 years starting with 2001
+            + ((year - 2000 + 399) / 400) // add a day each 400 years starting with 2001
+            ) * 86400
+        + (year - 2000) * 31536000;
+}
+
+mp_uint_t timeutils_mktime(mp_uint_t year, mp_uint_t month, mp_uint_t mday,
+    mp_uint_t hours, mp_uint_t minutes, mp_uint_t seconds) {
+
+    // Normalize the tuple. This allows things like:
+    //
+    // tm_tomorrow = list(time.localtime())
+    // tm_tomorrow[2] += 1 # Adds 1 to mday
+    // tomorrow = time.mktime(tm_tommorrow)
+    //
+    // And not have to worry about all the weird overflows.
+    //
+    // You can subtract dates/times this way as well.
+
+    minutes += seconds / 60;
+    if ((seconds = seconds % 60) < 0) {
+        seconds += 60;
+        minutes--;
+    }
+
+    hours += minutes / 60;
+    if ((minutes = minutes % 60) < 0) {
+        minutes += 60;
+        hours--;
+    }
+
+    mday += hours / 24;
+    if ((hours = hours % 24) < 0) {
+        hours += 24;
+        mday--;
+    }
+
+    month--; // make month zero based
+    year += month / 12;
+    if ((month = month % 12) < 0) {
+        month += 12;
+        year--;
+    }
+    month++; // back to one based
+
+    while (mday < 1) {
+        if (--month == 0) {
+            month = 12;
+            year--;
+        }
+        mday += timeutils_days_in_month(year, month);
+    }
+    while (mday > timeutils_days_in_month(year, month)) {
+        mday -= timeutils_days_in_month(year, month);
+        if (++month == 13) {
+            month = 1;
+            year++;
+        }
+    }
+    return timeutils_seconds_since_2000(year, month, mday, hours, minutes, seconds);
+}