add support code for future modifications;

src/Clock.cpp

@@ -0,0 +1,212 @@
+/**
+* Digital Voice Modem - Host Software
+* GPLv2 Open Source. Use is subject to license terms.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* @package DVM / Host Software
+*
+*/
+/*
+*   Copyright (C) 2023 Bryan Biedenkapp N2PLL
+*
+*   This program 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; version 2 of the License.
+*
+*   This program 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.
+*/
+#include "Defines.h"
+#include "Clock.h"
+
+using namespace system_clock;
+
+#include <stdio.h>
+
+// ---------------------------------------------------------------------------
+//  Constants
+// ---------------------------------------------------------------------------
+
+static const uint64_t EPOCH = 2208988800ULL;
+static const uint64_t NTP_SCALE_FRAC = 4294967296ULL;
+
+// ---------------------------------------------------------------------------
+//  Global Functions
+// ---------------------------------------------------------------------------
+
+/// <summary>
+///
+/// </summary>
+/// <param name="older"></param>
+/// <param name="newer"></param>
+/// <returns></returns>
+static inline uint32_t ntpDiffMS(uint64_t older, uint64_t newer)
+{
+    if (older > newer) {
+        // LOG_ERROR("Older timestamp is actually newer");
+    }
+
+    uint32_t s1  = (older >> 32) & 0xffffffff;
+    uint32_t s2  = (newer >> 32) & 0xffffffff;
+    uint64_t us1 = ((older & 0xffffffff) * 1000000UL) / NTP_SCALE_FRAC;
+    uint64_t us2 = ((newer & 0xffffffff) * 1000000UL) / NTP_SCALE_FRAC;
+
+    uint64_t r = (((uint64_t)(s2 - s1) * 1000000) + ((us2 - us1))) / 1000;
+
+    if (r > UINT32_MAX) {
+        // LOG_ERROR("NTP difference is too large: %llu. Limiting value", r);
+        r = UINT32_MAX;
+    }
+
+    return (uint32_t)r;
+}
+
+/// <summary>
+/// Get current time in NTP units.
+/// </summary>
+/// <returns>NTP timestamp.</returns>
+uint64_t ntp::now()
+{
+    struct timeval tv;
+#ifdef _WIN32
+    gettimeofday(&tv, NULL);
+#else
+    gettimeofday(&tv, NULL);
+#endif
+
+    uint64_t tv_ntp = tv.tv_sec + EPOCH;
+    uint64_t tv_usecs = (uint64_t)((float)(NTP_SCALE_FRAC * tv.tv_usec) / 1000000.f);
+
+    return (tv_ntp << 32) | tv_usecs;
+}
+
+/// <summary>
+/// Calculate the time difference of two NTP times.
+/// </summary>
+/// <param name="ntp1">First NTP timestamp</param>
+/// <param name="ntp2">Second NTP timestamp</param>
+/// <returns>Difference of the timestamps in milliseconds.</returns>
+uint64_t ntp::diff(uint64_t ntp1, uint64_t ntp2)
+{
+    return ntpDiffMS(ntp1, ntp2);
+}
+
+/// <summary>
+/// Calculate the time difference of two NTP times.
+///
+/// This function calls clock::ntp::now() and then subtracts the input 
+/// parameter from that timestamp value.
+/// </summary>
+/// <param name="then">NTP timestamp</param>
+/// <returns>Difference of the timestamps in milliseconds.</returns>
+uint64_t ntp::diffNow(uint64_t then)
+{
+    uint64_t now = ntp::now();
+    return ntpDiffMS(then, now);
+}
+
+/// <summary>
+/// Get current time in HRC units.
+/// </summary>
+/// <returns>NTP timestamp.</returns>
+hrc::hrc_t hrc::now()
+{
+    return std::chrono::high_resolution_clock::now();
+}
+
+/// <summary>
+/// Calculate the time difference of two HRC times.
+/// </summary>
+/// <param name="hrc1">First HRC timestamp</param>
+/// <param name="hrc2">Second HRC timestamp</param>
+/// <returns>Difference of the timestamps in milliseconds.</returns>
+uint64_t hrc::diff(hrc::hrc_t hrc1, hrc::hrc_t hrc2)
+{
+    return std::chrono::duration_cast<std::chrono::milliseconds>(hrc1 - hrc2).count();
+}
+
+/// <summary>
+/// Calculate the time difference of two HRC times.
+///
+/// This function calls clock::hrc::now() and then subtracts the input 
+/// parameter from that timestamp value.
+/// </summary>
+/// <param name="then">HRC timestamp</param>
+/// <returns>Difference of the timestamps in milliseconds.</returns>
+uint64_t hrc::diffNow(hrc::hrc_t then)
+{
+    return (uint64_t)std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::high_resolution_clock::now() - then).count();
+}
+
+/// <summary>
+/// Calculate the time difference of two HRC times.
+///
+/// This function calls clock::hrc::now() and then subtracts the input 
+/// parameter from that timestamp value.
+/// </summary>
+/// <param name="then">HRC timestamp</param>
+/// <returns>Difference of the timestamps in microseconds.</returns>
+uint64_t hrc::diffNowUS(hrc::hrc_t& then)
+{
+    return (uint64_t)std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::high_resolution_clock::now() - then).count();
+}
+
+/// <summary>
+///
+/// </summary>
+/// <param name="ms"></param>
+/// <returns></returns>
+uint64_t msToJiffies(uint64_t ms)
+{
+    return (uint64_t)(((double)ms/1000)* 65536);
+}
+
+/// <summary>
+///
+/// </summary>
+/// <param name="ms"></param>
+/// <returns></returns>
+uint64_t jiffiesToMs(uint64_t jiffies)
+{
+    return (uint64_t)(((double)jiffies / 65536) * 1000);
+}
+
+#ifdef _WIN32
+/// <summary>
+///
+/// </summary>
+/// <param name="tp"></param>
+/// <param name="tzp"></param>
+/// <returns></returns>
+int gettimeofday(struct timeval* tp, struct timezone* tzp)
+{
+    if (tzp != nullptr) {
+        // LOG_ERROR("Timezone not supported");
+        return -1;
+    }
+
+    // https://stackoverflow.com/questions/10905892/equivalent-of-gettimeday-for-windows
+
+    // Note: some broken versions only have 8 trailing zero's, the correct epoch has 9 trailing zero's
+    // This magic number is the number of 100 nanosecond intervals since January 1, 1601 (UTC)
+    // until 00:00:00 January 1, 1970
+    static const uint64_t epoch = ((uint64_t) 116444736000000000ULL);
+
+    // TODO: Why do we have two epochs defined?
+
+    SYSTEMTIME system_time;
+    FILETIME file_time;
+    uint64_t time;
+
+    GetSystemTime(&system_time);
+    SystemTimeToFileTime(&system_time, &file_time);
+    time = ((uint64_t)file_time.dwLowDateTime);
+    time += ((uint64_t)file_time.dwHighDateTime) << 32;
+
+    tp->tv_sec = (long)((time - epoch) / 10000000L);
+    tp->tv_usec = (long)(system_time.wMilliseconds * 1000);
+    return 0;
+}
+#endif

src/Clock.h

@@ -0,0 +1,77 @@
+/**
+* Digital Voice Modem - Host Software
+* GPLv2 Open Source. Use is subject to license terms.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* @package DVM / Host Software
+*
+*/
+/*
+*   Copyright (C) 2023 Bryan Biedenkapp N2PLL
+*
+*   This program 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; version 2 of the License.
+*
+*   This program 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.
+*/
+#if !defined(__CLOCK_H__)
+#define __CLOCK_H__
+
+#include "Defines.h"
+
+#ifdef _WIN32
+#include <winsock2.h>
+#else
+#include <sys/time.h>
+#endif
+
+#include <chrono>
+
+namespace system_clock 
+{
+    /* 
+    ** Network Time Protocol
+    */
+    namespace ntp 
+    {
+        /// <summary>Get current time in NTP units.</summary>
+        uint64_t now();
+        /// <summary>Calculate the time difference of two NTP times.</summary>
+        uint64_t diff(uint64_t ntp1, uint64_t ntp2);
+        /// <summary>Calculate the time difference of two NTP times.</summary>
+        uint64_t diffNow(uint64_t then);
+    } // namespace ntp
+
+    /*
+    ** High-Resolution Clock 
+    */
+    namespace hrc 
+    {
+        typedef std::chrono::high_resolution_clock::time_point hrc_t;
+
+        /// <summary>Get current time in HRC units.</summary>
+        hrc_t now();
+        /// <summary>Calculate the time difference of two HRC times.</summary>
+        uint64_t diff(hrc_t hrc1, hrc_t hrc2);
+        /// <summary>Calculate the time difference of two HRC times.</summary>
+        uint64_t diffNow(hrc_t then);
+        /// <summary>Calculate the time difference of two HRC times.</summary>
+        uint64_t diffNowUS(hrc_t& then);
+    } // namespace hrc
+
+    /// <summary></summary>
+    uint64_t msToJiffies(uint64_t ms);
+    /// <summary></summary>
+    uint64_t jiffiesToMs(uint64_t jiffies);
+
+#ifdef _WIN32
+    /// <summary></summary>
+    int gettimeofday(struct timeval *tp, struct timezone *tzp);
+#endif
+} // namespace system_clock
+
+#endif // __CLOCK_H__