text: /*
   * Copyright (C) 2008 The Android Open Source Project
   *
   * 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.
   */
  
  
  /*
   * System clock functions.
   */
  
  #ifdef HAVE_ANDROID_OS
  #include <linux/ioctl.h>
  #include <linux/rtc.h>
  #include <utils/Atomic.h>
  #include <linux/android_alarm.h>
  #endif
  
  #include <sys/time.h>
  #include <limits.h>
  #include <fcntl.h>
  #include <errno.h>
  #include <string.h>
  
  #include <utils/SystemClock.h>
  #include <utils/Timers.h>
  
  #define LOG_TAG "SystemClock"
  #include <utils/Log.h>
  
  #if HAVE_QC_TIME_SERVICES
  extern "C" {
  #include <utils/time_genoff.h>
  }
  #endif
  
  namespace android {
  
  #if HAVE_QC_TIME_SERVICES
  int setTimeServicesTime(time_bases_type base, int64_t millis)
  {
      int rc = 0;
      time_genoff_info_type time_set;
      uint64_t value = millis;
      time_set.base = base;
      time_set.unit = TIME_MSEC;
      time_set.operation = T_SET;
      time_set.ts_val = &value;
      rc = time_genoff_operation(&time_set);
      if (rc) {
          ALOGE("Error setting generic offset: %d. Still setting system time\n", rc);
          rc = -1;
      }
      return rc;
  }
  #endif
  /*
   * Set the current time.  This only works when running as root.
   */
  int setCurrentTimeMillis(int64_t millis)
  {
  #if WIN32
      // not implemented
      return -1;
  #else
      struct timeval tv;
  #ifdef HAVE_ANDROID_OS
      struct timespec ts;
      int fd;
      int res;
  #endif
      int ret = 0;
  
  #if HAVE_QC_TIME_SERVICES
      int rc;
      rc = setTimeServicesTime(ATS_USER, millis);
      if (rc) {
          ALOGE("Error setting generic offset: %d. Still setting system time\n", rc);
      }
  #endif
  
      if (millis <= 0 || millis / 1000LL >= INT_MAX) {
          return -1;
      }
  
      tv.tv_sec = (time_t) (millis / 1000LL);
      tv.tv_usec = (suseconds_t) ((millis % 1000LL) * 1000LL);
  
      ALOGD("Setting time of day to sec=%d\n", (int) tv.tv_sec);
  
  #ifdef HAVE_ANDROID_OS
      fd = open("/dev/alarm", O_RDWR);
      if(fd < 0) {
          ALOGW("Unable to open alarm driver: %s\n", strerror(errno));
          return -1;
      }
      ts.tv_sec = tv.tv_sec;
      ts.tv_nsec = tv.tv_usec * 1000;
      res = ioctl(fd, ANDROID_ALARM_SET_RTC, &ts);
      if(res < 0) {
          ALOGW("Unable to set rtc to %ld: %s\n", tv.tv_sec, strerror(errno));
          ret = -1;
      }
      close(fd);
  #else
      if (settimeofday(&tv, NULL) != 0) {
          ALOGW("Unable to set clock to %d.%d: %s\n",
              (int) tv.tv_sec, (int) tv.tv_usec, strerror(errno));
          ret = -1;
      }
  #endif
  
      return ret;
  #endif // WIN32
  }
  
  /*
   * native public static long uptimeMillis();
   */
  int64_t uptimeMillis()
  {
      int64_t when = systemTime(SYSTEM_TIME_MONOTONIC);
      return (int64_t) nanoseconds_to_milliseconds(when);
  }
  
  /*
   * native public static long elapsedRealtime();
   */
  int64_t elapsedRealtime()
  {
  	return nanoseconds_to_milliseconds(elapsedRealtimeNano());
  }
  
  #define METHOD_CLOCK_GETTIME    0
  #define METHOD_IOCTL            1
  #define METHOD_SYSTEMTIME       2
  
  /*
   * To debug/verify the timestamps returned by the kernel, change
   * DEBUG_TIMESTAMP to 1 and call the timestamp routine from a single thread
   * in the test program. b/10899829
   */
  #define DEBUG_TIMESTAMP         0
  
  static const char *gettime_method_names[] = {
      "clock_gettime",
      "ioctl",
      "systemTime",
  };
  
  #if DEBUG_TIMESTAMP
  static inline void checkTimeStamps(int64_t timestamp,
                                     int64_t volatile *prevTimestampPtr,
                                     int volatile *prevMethodPtr,
                                     int curMethod)
  {
      /*
       * Disable the check for SDK since the prebuilt toolchain doesn't contain
       * gettid, and int64_t is different on the ARM platform
       * (ie long vs long long).
       */
  #ifdef ARCH_ARM
      int64_t prevTimestamp = *prevTimestampPtr;
      int prevMethod = *prevMethodPtr;
  
      if (timestamp < prevTimestamp) {
          ALOGW("time going backwards: prev %lld(%s) vs now %lld(%s), tid=%d",
                prevTimestamp, gettime_method_names[prevMethod],
                timestamp, gettime_method_names[curMethod],
                gettid());
      }
      // NOTE - not atomic and may generate spurious warnings if the 64-bit
      // write is interrupted or not observed as a whole.
      *prevTimestampPtr = timestamp;
      *prevMethodPtr = curMethod;
  #endif
  }
  #else
  #define checkTimeStamps(timestamp, prevTimestampPtr, prevMethodPtr, curMethod)
  #endif
  
  /*
   * native public static long elapsedRealtimeNano();
   */
  int64_t elapsedRealtimeNano()
  {
  #ifdef HAVE_ANDROID_OS
      struct timespec ts;
      int result;
      int64_t timestamp;
  #if DEBUG_TIMESTAMP
      static volatile int64_t prevTimestamp;
      static volatile int prevMethod;
  #endif
  
  #if 0
      /*
       * b/7100774
       * clock_gettime appears to have clock skews and can sometimes return
       * backwards values. Disable its use until we find out what's wrong.
       */
      result = clock_gettime(CLOCK_BOOTTIME, &ts);
      if (result == 0) {
          timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
          checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
                          METHOD_CLOCK_GETTIME);
          return timestamp;
      }
  #endif
  
      // CLOCK_BOOTTIME doesn't exist, fallback to /dev/alarm
      static int s_fd = -1;
  
      if (s_fd == -1) {
          int fd = open("/dev/alarm", O_RDONLY);
          if (android_atomic_cmpxchg(-1, fd, &s_fd)) {
              close(fd);
          }
      }
  
      result = ioctl(s_fd,
              ANDROID_ALARM_GET_TIME(ANDROID_ALARM_ELAPSED_REALTIME), &ts);
  
      if (result == 0) {
          timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
          checkTimeStamps(timestamp, &prevTimestamp, &prevMethod, METHOD_IOCTL);
          return timestamp;
      }
  
      // XXX: there was an error, probably because the driver didn't
      // exist ... this should return
      // a real error, like an exception!
      timestamp = systemTime(SYSTEM_TIME_MONOTONIC);
      checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
                      METHOD_SYSTEMTIME);
      return timestamp;
  #else
      return systemTime(SYSTEM_TIME_MONOTONIC);
  #endif
  }
  
  }; // namespace android
  