sys/phydat: add functions for Unix time conversion to phydat

sys/include/phydat.h

@@ -288,6 +288,35 @@ void phydat_fit(phydat_t *dat, const int32_t *values, unsigned int dim);
  */
 size_t phydat_to_json(const phydat_t *data, size_t dim, char *buf);
 
+/**
+ * @brief   Convert a date and time contained in phydat structs to a Unix timestamp.
+ *          See phydat_unix() for the date notation and peculiarities.
+ *
+ * @param date              Date to use in the timestamp.
+ * @param time              Time to use in the timestamp.
+ * @param offset_seconds    Timezone offset in seconds to use in the timestamp.
+ *
+ * @return  A unix timestamp
+ */
+int64_t phydat_date_time_to_unix(phydat_t *date, phydat_t *time, int32_t offset_seconds);
+
+/**
+ * @brief   Convert a date and time (per ISO8601) to a Unix timestamp (seconds since 1970).
+ *
+ * @param year      Year in the Common Era (CE). Note that 0 is 1 BCE, 1 is 2 BCE, etc.
+ * @param month     Month of the year.
+ * @param day       Day of the month.
+ * @param hour      Hour of the day.
+ * @param minute    Minute of the hour.
+ * @param second    Second of the minute.
+ * @param offset    Timezone offset in seconds.
+ *
+ * @return          A Unix timestamp (seconds since 1970).
+ */
+int64_t phydat_unix(int16_t year, int16_t month, int16_t day,
+                    int16_t hour, int16_t minute, int16_t second,
+                    int32_t offset);
+
 #ifdef __cplusplus
 }
 #endif

sys/phydat/phydat_unix.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2023 Silke Hofstra
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+#include <stdint.h>
+#include <math.h>
+
+#include "phydat.h"
+
+/**
+ * Offsets of the first day of the month starting with January.
+ * Months after February have a negative offset to efficiently handle leap years.
+ */
+static int16_t month_to_yday[] = { 0,      31, -306, -275, -245, -214,
+                                   -184, -153, -122,  -92,  -61,  -31 };
+
+static inline int16_t phydat_unscale(int16_t value, int16_t scale)
+{
+    if (scale > 0) {
+        return value * pow(10, scale);
+    }
+
+    if (scale < 0) {
+        return value / pow(10, -scale);
+    }
+
+    return value;
+}
+
+int64_t phydat_date_time_to_unix(phydat_t *date, phydat_t *time, int32_t offset_seconds)
+{
+    return phydat_unix(
+        phydat_unscale(date->val[2], date->scale),
+        phydat_unscale(date->val[1], date->scale),
+        phydat_unscale(date->val[0], date->scale),
+        phydat_unscale(time->val[2], time->scale),
+        phydat_unscale(time->val[1], time->scale),
+        phydat_unscale(time->val[0], time->scale),
+        offset_seconds);
+}
+
+int64_t phydat_unix(int16_t year, int16_t month, int16_t day,
+                    int16_t hour, int16_t minute, int16_t second,
+                    int32_t offset_seconds)
+{
+    /* Make the year relative to 1900. */
+    /* Add a year for months after Feb to deal with leap years. */
+    year += (month > 2 ? 1 : 0) - 1900;
+
+    /* Calculate the day of the year based on the month */
+    day += month_to_yday[(month - 1) % 12] - 1;
+
+    /* POSIX calculation of a UNIX timestamp. */
+    /* See section 4.16 of The Open Group Base Specifications Issue 7. */
+    int16_t leap_days = ((year - 69) / 4) - ((year - 1) / 100) + ((year + 299) / 400);
+
+    return (int64_t)(day + leap_days) * 86400 +
+           (int64_t)(year - 70) * 31536000 +
+           (int64_t)(hour) * 3600 +
+           (int64_t)(minute) * 60 +
+           (int64_t)(second) -
+           offset_seconds;
+}

tests/phydat_unix/Makefile

@@ -0,0 +1,6 @@
+include ../Makefile.tests_common
+
+USEMODULE += phydat
+USEMODULE += embunit
+
+include $(RIOTBASE)/Makefile.include

tests/phydat_unix/Makefile.ci

@@ -0,0 +1,10 @@
+BOARD_INSUFFICIENT_MEMORY := \
+    arduino-duemilanove \
+    arduino-nano \
+    arduino-uno \
+    atmega328p \
+    atmega328p-xplained-mini \
+    nucleo-l011k4 \
+    samd10-xmini \
+    stm32f030f4-demo \
+    #

tests/phydat_unix/app.config.test

@@ -0,0 +1,2 @@
+CONFIG_MODULE_PHYDAT=y
+CONFIG_MODULE_EMBUNIT=y

tests/phydat_unix/main.c

@@ -0,0 +1,213 @@
+/*
+ * Copyright (C) 2023 Silke Hofstra
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     tests
+ * @{
+ *
+ * @file
+ * @brief       Phydat Unix timestamp tests
+ *
+ * @author      Silke Hofstra <silke@slxh.eu>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+
+#include "phydat.h"
+#include "embUnit.h"
+
+#define ENABLE_DEBUG 0
+#include "debug.h"
+
+#ifndef PRIi64
+#define PRIi64 "lli"
+#endif
+
+typedef struct {
+    phydat_t date;
+    phydat_t time;
+    int32_t offset;
+    int64_t ts;
+} test_t;
+
+static test_t tests[] = {
+    /* Test various ways of writing 0 */
+    {
+        .date = { { 1, 1, 1970 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = 0,
+    },
+    {
+        .date = { { 1, 1, 1970 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 2 }, UNIT_TIME, 0 },
+        .offset = 7200,     /* UTC +0200 */
+        .ts = 0,
+    },
+    {
+        .date = { { 31, 12, 1969 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 22 }, UNIT_TIME, 0 },
+        .offset = -7200,     /* UTC -0200 */
+        .ts = 0,
+    },
+    {
+        .date = { { 1, 1, 1970 }, UNIT_DATE, 0 },
+        .time = { { 3600, 60, 0 }, UNIT_TIME, 0 },
+        .offset = 7200,       /* UTC +0200 */
+        .ts = 0,
+    },
+    {
+        .date = { { 31, 12, 1969 }, UNIT_DATE, 0 },
+        .time = { { 3600, 120, 19 }, UNIT_TIME, 0 },
+        .offset = -7200,       /* UTC -0200 */
+        .ts = 0,
+    },
+
+    /* Test well-known dates */
+    {
+        .date = { { 28, 4, 2021 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = 1619568000,
+    },
+    {
+        .date = { { 29, 2, 2020 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = 1582934400,
+    },
+    {
+        .date = { { 1, 3, 2020 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = 1583020800,
+    },
+
+    /* Test the first of every month */
+    {
+        .date = { { 1, 1, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2208988800,
+    },
+    {
+        .date = { { 1, 2, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2206310400,
+    },
+    {
+        .date = { { 1, 3, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2203891200,
+    },
+    {
+        .date = { { 1, 4, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2201212800,
+    },
+    {
+        .date = { { 1, 5, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2198620800,
+    },
+    {
+        .date = { { 1, 6, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2195942400,
+    },
+    {
+        .date = { { 1, 7, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2193350400,
+    },
+    {
+        .date = { { 1, 8, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2190672000,
+    },
+    {
+        .date = { { 1, 9, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2187993600,
+    },
+    {
+        .date = { { 1, 10, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2185401600,
+    },
+    {
+        .date = { { 1, 11, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2182723200,
+    },
+    {
+        .date = { { 1, 12, 1900 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = -2180131200,
+    },
+
+    /* Test scale correction */
+    {
+        .date = { { 1, 1, 197 }, UNIT_DATE, 1 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = 24364800,
+    },
+    {
+        .date = { { 10, 10, 19700 }, UNIT_DATE, -1 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = 0,
+    },
+    {
+        .date = { { 1, 1, 1970 }, UNIT_DATE, 0 },
+        .time = { { 36, 0, 0 }, UNIT_TIME, 2 },
+        .ts = 3600,
+    },
+
+    /* An invalid date that might go out of bounds on the day of the year lookup table */
+    {
+        .date = { { 1, 13, 1969 }, UNIT_DATE, 0 },
+        .time = { { 0, 0, 0 }, UNIT_TIME, 0 },
+        .ts = 0,
+    },
+};
+
+void test_phydat_date_time_to_unix(void)
+{
+    for (size_t i = 0; i < ARRAY_SIZE(tests); i++) {
+        int64_t result = phydat_date_time_to_unix(
+            &(tests[i].date),  &(tests[i].time), tests[i].offset);
+
+        int32_t offset_hours = tests[i].offset / 3600;
+        int32_t offset_minutes = (tests[i].offset % 3600) / 60;
+
+        DEBUG("Datetime: %04" PRIi16 "-%02" PRIi16 "-%02" PRIi16 "e%" PRIi16 " "
+              "%02" PRIi16 ":%02" PRIi16 ":%02" PRIi16 "e%" PRIi16 " "
+              "%+03" PRIi32 ":%02" PRIi32 " -> %" PRIi64 "\n",
+              tests[i].date.val[2], tests[i].date.val[1], tests[i].date.val[0], tests[i].date.scale,
+              tests[i].time.val[2], tests[i].time.val[1], tests[i].time.val[0], tests[i].time.scale,
+              offset_hours, offset_minutes, result);
+
+        TEST_ASSERT_EQUAL_INT(tests[i].ts, result);
+    }
+}
+
+Test *tests_phydat_unix(void)
+{
+    EMB_UNIT_TESTFIXTURES(fixtures) {
+        new_TestFixture(test_phydat_date_time_to_unix),
+    };
+    EMB_UNIT_TESTCALLER(senml_tests, NULL, NULL, fixtures);
+    return (Test *)&senml_tests;
+}
+
+int main(void)
+{
+    TESTS_START();
+    TESTS_RUN(tests_phydat_unix());
+    TESTS_END();
+    return 0;
+}

tests/phydat_unix/tests/01-run.py

@@ -0,0 +1,14 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2017 Freie Universität Berlin
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+import sys
+from testrunner import run_check_unittests
+
+
+if __name__ == "__main__":
+    sys.exit(run_check_unittests())