From 10ca03aab35f1203122e0b39f587e287451aed6e Mon Sep 17 00:00:00 2001
From: Martine Lenders <m.lenders@fu-berlin.de>
Date: Sat, 4 Mar 2017 22:04:59 +0100
Subject: [PATCH] sntp: extend API for UNIX timestamp

---
 sys/include/net/ntp_packet.h |  6 ++++++
 sys/include/net/sntp.h       | 15 +++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/sys/include/net/ntp_packet.h b/sys/include/net/ntp_packet.h
index 3484d54f64..51cd659744 100644
--- a/sys/include/net/ntp_packet.h
+++ b/sys/include/net/ntp_packet.h
@@ -46,6 +46,12 @@ extern "C" {
 #define NTP_VERSION          (4U)       /**< NTP version */
 #define NTP_PORT             (123U)     /**< NTP port number */
 
+/**
+ * @brief   Offset in seconds of NTP timestamp (seconds from 1990-01-01 00:00:00 UTC)
+ *          to UNIX timestamp (seconds from 1970-01-01 00:00:00 UTC).
+ */
+#define NTP_UNIX_OFFSET      (2208988800)
+
 /**
  * @brief NTP modes
  */
diff --git a/sys/include/net/sntp.h b/sys/include/net/sntp.h
index 23594a75a7..8e8d80a8ac 100644
--- a/sys/include/net/sntp.h
+++ b/sys/include/net/sntp.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2016 Luminița Lăzărescu <cluminita.lazarescu@gmail.com>
+ * 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
@@ -23,7 +24,11 @@
 #define SNTP_H
 
 #include <stdint.h>
+#include <time.h>
+
+#include "net/ntp_packet.h"
 #include "net/sock/udp.h"
+#include "xtimer.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -47,6 +52,16 @@ int sntp_sync(sock_udp_ep_t *server, uint32_t timeout);
  */
 int64_t sntp_get_offset(void);
 
+/**
+ * @brief   Get time in microseconds from 1970-01-01 00:00:00 UTC.
+ *
+ * @return  Time in microseconds from 1970-01-01 00:00:00 UTC
+ */
+static inline uint64_t sntp_get_unix_usec(void)
+{
+    return (uint64_t)(sntp_get_offset() - (NTP_UNIX_OFFSET * US_PER_SEC) + xtimer_now_usec64());
+}
+
 #ifdef __cplusplus
 }
 #endif