text: /*
   *                         Vortex OpenSplice
   *
   *   This software and documentation are Copyright 2006 to TO_YEAR ADLINK
   *   Technology Limited, its affiliated companies and licensors. All rights
   *   reserved.
   *
   *   Licensed under the Apache License, Version 2.0 (the "License");
   *   you may not use this file except in compliance with the License.
   *   You may obtain a copy of the License at
   *
   *       http://www.apache.org/licenses/LICENSE-2.0
   *
   *   Unless required by applicable law or agreed to in writing, software
   *   distributed under the License is distributed on an "AS IS" BASIS,
   *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *   See the License for the specific language governing permissions and
   *   limitations under the License.
   *
   */
  
  /** \file os/posix/code/os_time.c
   *  \brief Time management
   *
   * Implements posix based time management functions
   */
  
  #include <time.h>
  #include "os_errno.h"
  
  /*  \brief Get the current time
   */
  static os_timeW
  os__timeWGet(void)
  {
      struct timespec t;
      os_timeW rt;
  
      /* POSIX specifies that all implementations of clock_gettime(...)
       * support the system-wide real-time clock, which is identified
       * by CLOCK_REALTIME, so the result of the call below can safely
       * be ignored. */
      (void) clock_gettime (CLOCK_REALTIME, &t);
  
      rt = OS_TIMEW_INIT(t.tv_sec, t.tv_nsec);
  
      return rt;
  }
  
  /** \brief Get high resolution, monotonic time.
   *
   * Sufficiently recent versions of GNU libc and the Linux kernel support
   * monotonic clocks. In case monotonic clocks are NOT supported the
   * real-time clock is used as fallback. This ensures that the products
   * still works as long as no time jumps occur.
   *
   * \return high resolution, monotonic time if monotonic clocks are supported.
   * \return real-time, otherwise
   */
  os_timeM
  os_timeMGet(void)
  {
      os_timeM t;
      struct timespec tv;
  
  #ifdef _POSIX_MONOTONIC_CLOCK
      /* The CLOCK_MONOTONIC is the best (and most accurate) monotonic clock for
       * obtaining time with near real-time progression, since it may be slewed
       * based on NTP adjustments on some Linux providing more stable time
       * progression (assuming that the Caesium clocks are better at timekeeping
       * than the quartz crystal in an average PC). */
      (void) clock_gettime (CLOCK_MONOTONIC, &tv);
  #else
  
      /* Unfortunately no monotonic clock is supported for this POSIX platform.
       * Fall-back to the CLOCK_REALTIME instead. Unfortunately this means that
       * time jumps are not supported. */
      (void) clock_gettime (CLOCK_REALTIME, &tv);
  #endif
  
      t = OS_TIMEM_INIT(tv.tv_sec, tv.tv_nsec);
  
      return t;
  }
  
  /** \brief Get elapsed time.
   *
   * This is implemented by means of the CLOCK_BOOTTIME clock which is available
   * since Linux 2.6.39, but is Linux specific. If it is not available, the
   * monotonic clock will be used as a fall-back.
   *
   * \return elapsed time since some unspecified fixed past time
   * \return os_timeMGet() otherwise
   */
  os_timeE
  os_timeEGet(void)
  {
      os_timeE t;
  #ifdef CLOCK_BOOTTIME
      struct timespec tv;
  
      /* The CLOCK_BOOTTIME includes time spent during suspend, but is
       * Linux specific. */
      if ( 0 != clock_gettime (CLOCK_BOOTTIME, &tv)) { 
          /* Clock_boottime not supported, try monotonic */ 
          (void) clock_gettime (CLOCK_MONOTONIC, &tv); 
      }
      t = OS_TIMEE_INIT(tv.tv_sec, tv.tv_nsec);
  #else
      os_timeM m = os_timeMGet();
      t.et = m.mt;
  #endif /* CLOCK_MONOTONIC_BOOTTIME */
  
      return t;
  }
  
  /** \brief Suspend the execution of the calling thread for the specified time
   *
   * \b os_nanoSleep suspends the calling thread for the required
   * time by calling \b nanosleep. First it converts the \b delay in
   * \b os_duration definition into a time in \b struct \b timeval definition.
   * In case the \b nanosleep is interrupted, the call is re-entered with
   * the remaining time.
   */
  os_result
  ospl_os_sleep(
      os_duration delay)
  {
      struct timespec t;
      struct timespec r;
      int result;
      os_result rv;
  
      if (OS_DURATION_ISPOSITIVE(delay)) {
          /* Time should be normalized */
          t.tv_sec = (time_t) OS_DURATION_GET_SECONDS(delay);
          t.tv_nsec = OS_DURATION_GET_NANOSECONDS(delay);
          result = nanosleep (&t, &r);
          while (result && os_getErrno() == EINTR) {
              t = r;
              result = nanosleep (&t, &r);
          }
          if (result == 0) {
              rv = os_resultSuccess;
          } else {
              rv = os_resultFail;
          }
      } else {
          rv = os_resultFail;
      }
      return rv;
  }
  
  