Add libc time functions

Merging https://github.com/igrr/axtls-8266/pull/1 by @Juppit into the core

cores/esp8266/Arduino.h

@@ -271,6 +271,8 @@ long random(long, long);
 void randomSeed(unsigned long);
 long map(long, long, long, long, long);
 
+extern "C" void configTime(int timezone, int daylightOffset_sec,
+    const char* server1, const char* server2 = nullptr, const char* server3 = nullptr);
 
 #endif
 

cores/esp8266/libc_replacements.c

@@ -393,24 +393,6 @@ int* __errno(void) {
     return &errno_var;
 }
 
-
-char * ctime(const time_t *clock) {
-    return 0;
-}
-
-time_t time(time_t * t) {
-    return 0;
-}
-
-int gettimeofday(void *tp, void *tzp) {
-    return 0;
-}
-
-time_t mktime(struct tm *timp) {
-    return 0;
-}
-
-
 /*
  * begin newlib/string/strlcpy.c
  *

cores/esp8266/time.c

@@ -0,0 +1,128 @@
+/*
+ * time.c - ESP8266-specific functions for SNTP
+ * Copyright (c) 2015 Peter Dobler. All rights reserved.
+ * This file is part of the esp8266 core for Arduino environment.
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU Lesser General Public License for more details.
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+#include <time.h>
+#include "sntp.h"
+
+
+#ifndef _TIMEVAL_DEFINED
+#define _TIMEVAL_DEFINED
+struct timeval {
+  time_t      tv_sec;
+  suseconds_t tv_usec;
+};
+#endif
+
+extern char* sntp_asctime(const struct tm *t);
+extern struct tm* sntp_localtime(const time_t *clock);
+
+// time gap in seconds from 01.01.1900 (NTP time) to 01.01.1970 (UNIX time)
+#define DIFF1900TO1970 2208988800UL
+
+static int s_daylightOffset_sec = 0;
+static int s_timezone_sec = 0;
+static time_t s_bootTime = 0;
+
+// calculate offset used in gettimeofday
+static void ensureBootTimeIsSet()
+{
+    if (!s_bootTime)
+    {
+        time_t now = sntp_get_current_timestamp();
+        if (now)
+        {
+            s_bootTime =  - millis() / 1000;
+        }
+    }
+}
+
+static void setServer(int id, const char* name_or_ip)
+{
+    if (name_or_ip)
+    {
+        //TODO: check whether server is given by name or IP
+        sntp_setservername(0, (char*) name_or_ip);
+    }
+}
+
+void configTime(int timezone, int daylightOffset_sec, const char* server1, const char* server2, const char* server3)
+{
+    sntp_stop();
+
+    setServer(0, server1);
+    setServer(1, server2);
+    setServer(2, server3);
+
+    s_timezone_sec = timezone;
+    s_daylightOffset_sec = daylightOffset_sec;
+    sntp_set_timezone(timezone/3600);
+    sntp_init();
+}
+
+int clock_gettime(clockid_t unused, struct timespec *tp)
+{
+    tp->tv_sec  = millis() / 1000;
+    tp->tv_nsec = micros() * 1000;
+    return 0;
+}
+
+// seconds since 1970
+time_t mktime(struct tm *t)
+{
+    // system_mktime expects month in range 1..12
+    #define START_MONTH 1
+    return DIFF1900TO1970 + system_mktime(t->tm_year, t->tm_mon + START_MONTH, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec);
+}
+
+time_t time(time_t * t)
+{
+    time_t seconds = sntp_get_current_timestamp();
+    ensureBootTimeIsSet();
+    if (t)
+    {
+        *t = seconds;
+    }
+    return seconds;
+}
+
+char* asctime(const struct tm *t)
+{
+    return sntp_asctime(t);
+}
+
+struct tm* localtime(const time_t *clock)
+{
+    return sntp_localtime(clock);
+}
+
+char* ctime(const time_t *t)
+{
+    struct tm* p_tm = localtime(t);
+    char* result = asctime(p_tm);
+    return result;
+}
+
+int gettimeofday(struct timeval *tp, void *tzp)
+{
+    if (tp)
+    {
+        ensureBootTimeIsSet();
+        tp->tv_sec  = (s_bootTime + millis()) / 1000;
+        tp->tv_usec = micros() * 1000;
+    }
+}

tests/Time/Time.ino

@@ -0,0 +1,35 @@
+#include <ESP8266WiFi.h>
+#include <time.h>
+
+const char* ssid = "..........";
+const char* password = "..........";
+
+int timezone = 3;
+int dst = 0;
+
+void setup() {
+  Serial.begin(115200);
+  Serial.setDebugOutput(true);
+
+  WiFi.mode(WIFI_STA);
+  WiFi.begin(ssid, password);
+  Serial.println("\nConnecting to WiFi");
+  while (WiFi.status() != WL_CONNECTED) {
+    Serial.print(".");
+    delay(1000);
+  }
+
+  configTime(3 * 3600, 0, "pool.ntp.org", "time.nist.gov");
+  Serial.println("\nWaiting for time");
+  while (!time(nullptr)) {
+    Serial.print(".");
+    delay(1000);
+  }
+  Serial.println("");
+}
+
+void loop() {
+  time_t now = time(nullptr);
+  Serial.println(ctime(&now));
+  delay(1000);
+}