1 files changed, 76 insertions, 0 deletions
diff --git a/src/core/lib/gpr/time_precise.cc b/src/core/lib/gpr/time_precise.cc
new file mode 100644
index 0000000000..3c7aaabc40
--- /dev/null
+++ b/src/core/lib/gpr/time_precise.cc
@@ -0,0 +1,76 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * 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.
+ *
+ */
+
+#include <grpc/support/log.h>
+#include <grpc/support/time.h>
+#include <stdio.h>
+
+#include "src/core/lib/gpr/time_precise.h"
+
+#ifdef GRPC_TIMERS_RDTSC
+#if defined(__i386__)
+static void gpr_get_cycle_counter(int64_t int* clk) {
+  int64_t int ret;
+  __asm__ volatile("rdtsc" : "=A"(ret));
+  *clk = ret;
+}
+
+// ----------------------------------------------------------------
+#elif defined(__x86_64__) || defined(__amd64__)
+static void gpr_get_cycle_counter(int64_t* clk) {
+  uint64_t low, high;
+  __asm__ volatile("rdtsc" : "=a"(low), "=d"(high));
+  *clk = (int64_t)(high << 32) | (int64_t)low;
+}
+#endif
+
+static double cycles_per_second = 0;
+static int64_t start_cycle;
+void gpr_precise_clock_init(void) {
+  time_t start;
+  int64_t end_cycle;
+  gpr_log(GPR_DEBUG, "Calibrating timers");
+  start = time(NULL);
+  while (time(NULL) == start)
+    ;
+  gpr_get_cycle_counter(&start_cycle);
+  while (time(NULL) <= start + 10)
+    ;
+  gpr_get_cycle_counter(&end_cycle);
+  cycles_per_second = (double)(end_cycle - start_cycle) / 10.0;
+  gpr_log(GPR_DEBUG, "... cycles_per_second = %f\n", cycles_per_second);
+}
+
+void gpr_precise_clock_now(gpr_timespec* clk) {
+  int64_t counter;
+  double secs;
+  gpr_get_cycle_counter(&counter);
+  secs = (double)(counter - start_cycle) / cycles_per_second;
+  clk->clock_type = GPR_CLOCK_PRECISE;
+  clk->tv_sec = (int64_t)secs;
+  clk->tv_nsec = (int32_t)(1e9 * (secs - (double)clk->tv_sec));
+}
+
+#else  /* GRPC_TIMERS_RDTSC */
+void gpr_precise_clock_init(void) {}
+
+void gpr_precise_clock_now(gpr_timespec* clk) {
+  *clk = gpr_now(GPR_CLOCK_REALTIME);
+  clk->clock_type = GPR_CLOCK_PRECISE;
+}
+#endif /* GRPC_TIMERS_RDTSC */