test: add chrono.

test/chrono.cc

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2017 Leonid Yuriev <leo@yuriev.ru>
+ * and other libmdbx authors: please see AUTHORS file.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+
+#include "test.h"
+
+namespace chrono {
+
+#define NSEC_PER_SEC 1000000000u
+uint32_t ns2fractional(uint32_t ns) {
+  assert(ns < NSEC_PER_SEC);
+  /* LY: здесь и далее используется "длинное деление", которое
+   * для ясности кода оставлено как есть (без ручной оптимизации). Так как
+   * GCC, Clang и даже MSVC сами давно умеют конвертировать деление на
+   * константу в быструю reciprocal-форму. */
+  return ((uint64_t)ns << 32) / NSEC_PER_SEC;
+}
+
+uint32_t fractional2ns(uint32_t fractional) {
+  return (fractional * (uint64_t)NSEC_PER_SEC) >> 32;
+}
+
+#define USEC_PER_SEC 1000000u
+uint32_t us2fractional(uint32_t us) {
+  assert(us < USEC_PER_SEC);
+  return ((uint64_t)us << 32) / USEC_PER_SEC;
+}
+
+uint32_t fractional2us(uint32_t fractional) {
+  return (fractional * (uint64_t)USEC_PER_SEC) >> 32;
+}
+
+#define MSEC_PER_SEC 1000u
+uint32_t ms2fractional(uint32_t ms) {
+  assert(ms < MSEC_PER_SEC);
+  return ((uint64_t)ms << 32) / MSEC_PER_SEC;
+}
+
+uint32_t fractional2ms(uint32_t fractional) {
+  return (fractional * (uint64_t)MSEC_PER_SEC) >> 32;
+}
+
+time from_ns(uint64_t ns) {
+  time result;
+  result.fixedpoint = ((ns / NSEC_PER_SEC) << 32) |
+                      ns2fractional((uint32_t)(ns % NSEC_PER_SEC));
+  return result;
+}
+
+time from_us(uint64_t us) {
+  time result;
+  result.fixedpoint = ((us / USEC_PER_SEC) << 32) |
+                      us2fractional((uint32_t)(us % USEC_PER_SEC));
+  return result;
+}
+
+time from_ms(uint64_t ms) {
+  time result;
+  result.fixedpoint = ((ms / MSEC_PER_SEC) << 32) |
+                      ms2fractional((uint32_t)(ms % MSEC_PER_SEC));
+  return result;
+}
+
+time now() {
+#if defined(_WIN32) || defined(_WIN64) || defined(_WINDOWS)
+  FILETIME filetime;
+  GetSystemTimeAsFileTime(&filetime);
+  uint64_t ns =
+      (uint64_t)filetime.dwHighDateTime << 32 | filetime.dwLowDateTime;
+  return from_ns(ns);
+#else
+  struct timespec ts;
+  if (unlikely(clock_gettime(CLOCK_REALTIME, &ts)))
+    failure_perror("clock_gettime(CLOCK_REALTIME", errno);
+
+  return from_timespec(ts);
+#endif
+}
+
+} /* namespace chrono */