From 86f1ca90e53883d8a3501c4df4af7be9e4f7b4f9 Mon Sep 17 00:00:00 2001
From: Bert Belder <bertbelder@gmail.com>
Date: Tue, 19 Jul 2011 14:56:23 +0200
Subject: [PATCH] Windows: implement uv_hrtime()

---
 src/win/error.c |  1 +
 src/win/timer.c | 41 ++++++++++++++++++++++++++++++++++++++---
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/src/win/error.c b/src/win/error.c
index d7cf9866c..d44be2bb2 100644
--- a/src/win/error.c
+++ b/src/win/error.c
@@ -107,6 +107,7 @@ uv_err_code uv_translate_sys_error(int sys_errno) {
     case ERROR_TOO_MANY_OPEN_FILES:         return UV_EMFILE;
     case WSAEMFILE:                         return UV_EMFILE;
     case ERROR_OUTOFMEMORY:                 return UV_ENOMEM;
+    case ERROR_NOT_SUPPORTED:               return UV_ENOTSUP;
     case ERROR_INSUFFICIENT_BUFFER:         return UV_EINVAL;
     case ERROR_INVALID_FLAGS:               return UV_EBADF;
     case ERROR_INVALID_PARAMETER:           return UV_EINVAL;
diff --git a/src/win/timer.c b/src/win/timer.c
index 6f74a2ca0..d2ab89e93 100644
--- a/src/win/timer.c
+++ b/src/win/timer.c
@@ -26,10 +26,14 @@
 #include "internal.h"
 #include "tree.h"
 
+#undef NANOSEC
+#define NANOSEC 1000000000
+
 
 /* The resolution of the high-resolution clock. */
 static int64_t uv_ticks_per_msec_ = 0;
-
+static uint64_t uv_hrtime_frequency_ = 0;
+static char uv_hrtime_initialized_ = 0;
 
 
 void uv_update_time() {
@@ -48,8 +52,39 @@ int64_t uv_now() {
 
 
 uint64_t uv_hrtime(void) {
-  assert(0 && "implement me");
-  return 0;
+  LARGE_INTEGER counter;
+
+  /* When called for the first time, obtain the high-resolution clock */
+  /* frequency. */
+  if (!uv_hrtime_initialized_) {
+    uv_hrtime_initialized_ = 1;
+
+    if (!QueryPerformanceFrequency(&counter)) {
+      uv_hrtime_frequency_ = 0;
+      uv_set_sys_error(GetLastError());
+      return 0;
+    }
+
+    uv_hrtime_frequency_ = counter.QuadPart;
+  }
+
+  /* If the performance frequency is zero, there's no support. */
+  if (!uv_hrtime_frequency_) {
+    uv_set_sys_error(ERROR_NOT_SUPPORTED);
+    return 0;
+  }
+
+  if (!QueryPerformanceCounter(&counter)) {
+    uv_set_sys_error(GetLastError());
+    return 0;
+  }
+
+  /* Because we have no guarantee about the order of magniture of the */
+  /* performance counter frequency, and there may not be much headroom to */
+  /* multiply by NANOSEC without overflowing, we use 128-bit math instead. */
+  return ((uint64_t) counter.LowPart * NANOSEC / uv_hrtime_frequency_) +
+         (((uint64_t) counter.HighPart * NANOSEC / uv_hrtime_frequency_)
+         << 32);
 }