Add TAI handling for EDI with TIST

1 files changed, 220 insertions, 0 deletions

diff --git a/src/ClockTAI.cpp b/src/ClockTAI.cpp
new file mode 100644
index 0000000..1b2d4ef
--- /dev/null
+++ b/src/ClockTAI.cpp
@@ -0,0 +1,220 @@
+/*
+   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
+   2011, 2012 Her Majesty the Queen in Right of Canada (Communications
+   Research Center Canada)
+
+   Copyright (C) 2016
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+    http://www.opendigitalradio.org
+   */
+/*
+   This file is part of ODR-DabMux.
+
+   ODR-DabMux is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as
+   published by the Free Software Foundation, either version 3 of the
+   License, or (at your option) any later version.
+
+   ODR-DabMux 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with ODR-DabMux.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifdef HAVE_CONFIG_H
+#   include "config.h"
+#endif
+
+#include "ClockTAI.h"
+
+#include <stdio.h>
+#include <errno.h>
+#include <sys/timex.h>
+#include <curl/curl.h>
+#include <string>
+#include <iostream>
+#include <algorithm>
+#include <regex>
+
+/* Last line from bulletin, example:
+ 2015 JUL  1 =JD 2457204.5  TAI-UTC=  36.0       S + (MJD - 41317.) X 0.0      S
+ */
+
+ClockTAI::ClockTAI()
+{
+    m_offset = 0;
+    m_bulletin_download_time.tv_nsec = 0;
+    m_bulletin_download_time.tv_sec = 0;
+}
+
+int ClockTAI::get_offset()
+{
+    struct timespec time_now;
+
+    int err = clock_gettime(CLOCK_REALTIME, &time_now);
+    if (err) {
+        throw std::runtime_error("ClockTAI::get_offset() clock_gettime failed");
+    }
+
+    if (time_now.tv_sec - m_bulletin_download_time.tv_sec >
+            3600 * 24 * 31) {
+        // Refresh if it's older than one month. Leap seconds are
+        // announced several months in advance
+
+        if (download_tai_utc_bulletin(tai_data_url1) == 0) {
+            m_offset = parse_tai_offset();
+        }
+        else if (download_tai_utc_bulletin(tai_data_url2) == 0) {
+            m_offset = parse_tai_offset();
+        }
+    }
+
+    return m_offset;
+
+    throw std::runtime_error("Could not fetch TAI-UTC offset");
+}
+
+#if SUPPORT_SETTING_CLOCK_TAI
+int ClockTAI::update_local_tai_clock(int offset)
+{
+    struct timex timex_request;
+    timex_request.modes = ADJ_TAI;
+    timex_request.constant = offset;
+
+    int err = adjtimex(&timex_request);
+    if (err == -1) {
+        perror("adjtimex");
+    }
+
+    printf("adjtimex: %d, tai %d\n", err, timex_request.tai);
+
+    return err;
+}
+#endif
+
+int ClockTAI::parse_tai_offset()
+{
+    std::regex regex_offset("TAI-UTC= *([0-9.]+)");
+
+    int tai_utc_offset = 0;
+
+    int linecount = 0;
+
+    for (std::string line; std::getline(m_bulletin, line); ) {
+        linecount++;
+        auto words_begin =
+            std::sregex_token_iterator(
+                    line.begin(), line.end(), regex_offset, 1);
+        auto words_end = std::sregex_token_iterator();
+
+        for (auto w = words_begin; w != words_end; ++w) {
+            std::string s(*w);
+            tai_utc_offset = std::atoi(s.c_str());
+        }
+
+    }
+
+    if (linecount == 0) {
+        throw std::runtime_error("No data in TAI bulletin");
+    }
+
+    // With the current evolution of the offset, we're probably going
+    // to reach 500 long after DAB gets replaced by another standard.
+    if (tai_utc_offset < 0 or tai_utc_offset > 500) {
+        std::stringstream ss;
+        ss << "TAI offset " << tai_utc_offset << " out of range";
+        throw std::range_error(ss.str());
+    }
+
+    return tai_utc_offset;
+}
+
+size_t ClockTAI::fill_bulletin(char *ptr, size_t size, size_t nmemb)
+{
+    size_t len = size * nmemb;
+    for (size_t i = 0; i < len; i++) {
+        m_bulletin << ptr[i];
+    }
+    return len;
+}
+
+size_t ClockTAI::fill_bulletin_cb(
+        char *ptr, size_t size, size_t nmemb, void *ctx)
+{
+    return ((ClockTAI*)ctx)->fill_bulletin(ptr, size, nmemb);
+}
+
+int ClockTAI::download_tai_utc_bulletin(const char* url)
+{
+    int r = 0;
+
+    CURL *curl;
+    CURLcode res;
+
+    curl = curl_easy_init();
+    if (curl) {
+        curl_easy_setopt(curl, CURLOPT_URL, url);
+        /* example.com is redirected, so we tell libcurl to follow redirection */
+        curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
+        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, ClockTAI::fill_bulletin_cb);
+        curl_easy_setopt(curl, CURLOPT_WRITEDATA, this);
+
+        res = curl_easy_perform(curl);
+        if (res != CURLE_OK) {
+            fprintf(stderr, "curl_easy_perform() failed: %s\n",
+                    curl_easy_strerror(res));
+
+            r = 1;
+        }
+        else {
+            // Save the download time of the bulletin
+            int err = clock_gettime(CLOCK_REALTIME, &m_bulletin_download_time);
+            if (err) {
+                perror("REALTIME clock_gettime failed");
+                r = 1;
+            }
+        }
+
+        /* always cleanup */
+        curl_easy_cleanup(curl);
+    }
+    return r;
+}
+
+#if 0
+// Example testing code
+void debug_tai_clk()
+{
+    struct timespec rt_clk;
+
+    int err = clock_gettime(CLOCK_REALTIME, &rt_clk);
+    if (err) {
+        perror("REALTIME clock_gettime failed");
+    }
+
+    struct timespec tai_clk;
+
+    err = clock_gettime(CLOCK_TAI, &tai_clk);
+    if (err) {
+        perror("TAI clock_gettime failed");
+    }
+
+    printf("RT - TAI = %ld\n", rt_clk.tv_sec - tai_clk.tv_sec);
+
+
+    struct timex timex_request;
+    timex_request.modes = 0; // Do not set anything
+
+    err = adjtimex(&timex_request);
+    if (err == -1) {
+        perror("adjtimex");
+    }
+
+    printf("adjtimex: %d, tai %d\n", err, timex_request.tai);
+}
+#endif
+