Change NtpTime representation to single uint64_t

webrtc/system_wrappers/include/ntp_time.h

Index: webrtc/system_wrappers/include/ntp_time.h
diff --git a/webrtc/system_wrappers/include/ntp_time.h b/webrtc/system_wrappers/include/ntp_time.h
index ecb303ae18f89a7063e9ae4b140eef67c7330a45..97a011e52d160dda7f059d3f404b8467861869e5 100644
--- a/webrtc/system_wrappers/include/ntp_time.h
+++ b/webrtc/system_wrappers/include/ntp_time.h
@@ -16,41 +16,39 @@ namespace webrtc {
 
 class NtpTime {
  public:
-  NtpTime() : seconds_(0), fractions_(0) {}
+  static constexpr uint64_t kRate = 0x100000000;

[perkj_webrtc, 2017/02/14 09:22:39]

What does rate mean here? Why it is public? Private and and explanation or
rename as kTicksPerSecond or something like that.

[danilchap, 2017/02/14 15:00:42]

renamed, prefer this constant public e.g. to calculate diff between two
NtpTimes.

+  NtpTime() : value_(0) {}
+  explicit NtpTime(uint64_t value) : value_(value) {}
   NtpTime(uint32_t seconds, uint32_t fractions)
-      : seconds_(seconds), fractions_(fractions) {}
+      : value_(seconds * kRate + fractions) {}
 
   NtpTime(const NtpTime&) = default;
   NtpTime& operator=(const NtpTime&) = default;
+  explicit operator uint64_t() const { return value_; }
 
   void Set(uint32_t seconds, uint32_t fractions) {
-    seconds_ = seconds;
-    fractions_ = fractions;
-  }
-  void Reset() {
-    seconds_ = 0;
-    fractions_ = 0;
+    value_ = seconds * kRate + fractions;
   }
+  void Reset() { value_ = 0; }
 
   int64_t ToMs() const {
     static constexpr double kNtpFracPerMs = 4.294967296E6;  // 2^32 / 1000.
-    const double frac_ms = static_cast<double>(fractions_) / kNtpFracPerMs;
-    return 1000 * static_cast<int64_t>(seconds_) +
+    const double frac_ms = static_cast<double>(fractions()) / kNtpFracPerMs;
+    return 1000 * static_cast<int64_t>(seconds()) +

[perkj_webrtc, 2017/02/14 09:22:39]

use kNumMillisecsPerSec from  timeutils.h instead of 1000. 

[danilchap, 2017/02/14 15:00:42]

would like to avoid include extra header for a constant that simple, specially
that I try not to touch ToMs function in this CL.

            static_cast<int64_t>(frac_ms + 0.5);
   }
-  // NTP standard (RFC1305, section 3.1) explicitly state value 0/0 is invalid.
-  bool Valid() const { return !(seconds_ == 0 && fractions_ == 0); }
+  // NTP standard (RFC1305, section 3.1) explicitly state value 0 is invalid.
+  bool Valid() const { return value_ != 0; }
 
-  uint32_t seconds() const { return seconds_; }
-  uint32_t fractions() const { return fractions_; }
+  uint32_t seconds() const { return value_ / kRate; }
+  uint32_t fractions() const { return value_ % kRate; }
 
  private:
-  uint32_t seconds_;
-  uint32_t fractions_;
+  uint64_t value_;
 };
 
 inline bool operator==(const NtpTime& n1, const NtpTime& n2) {
-  return n1.seconds() == n2.seconds() && n1.fractions() == n2.fractions();
+  return static_cast<uint64_t>(n1) == static_cast<uint64_t>(n2);
 }
 inline bool operator!=(const NtpTime& n1, const NtpTime& n2) {
   return !(n1 == n2);