implement a high-precision timer

untested on OSX so far

Signed-off-by: Stanislaw Halik <sthalik@misaki.pl>

1 files changed, 67 insertions, 0 deletions

diff --git a/facetracknoir/timer.hpp b/facetracknoir/timer.hpp
new file mode 100644
index 00000000..306bcaa7
--- /dev/null
+++ b/facetracknoir/timer.hpp
@@ -0,0 +1,67 @@
+#pragma once
+#include <time.h>
+#if defined (_WIN32)
+#include <windows.h>
+static inline void clock_gettime(int, struct timespec* ts)
+{
+    static LARGE_INTEGER freq = 0;
+
+    if (!freq)
+        (void) QueryPerformanceFrequency(&freq);
+
+    freq.QuadPart /= 1000000;
+
+    LARGE_INTEGER d;
+
+    (void) QueryPerformanceCounter(&d);
+
+    d.QuadPart = d.QuadPart / freq.QuadPart;
+
+    ts->tv_sec = d.QuadPart / 1000000;
+    ts->tv_nsec = d.QuadPart % 1000000;
+}
+
+#else
+#   if defined(__MACH__)
+#       define CLOCK_MONOTONIC 0
+#       include <inttypes.h>
+#       include <mach/mach_time.h>
+static inline void clock_gettime(int, struct timespec* ts)
+{
+    uint64_t state, nsec;
+    static mach_timebase_info_data_t    sTimebaseInfo;
+    if ( sTimebaseInfo.denom == 0 ) {
+        (void) mach_timebase_info(&sTimebaseInfo);
+    }
+    state = mach_absolute_time();
+    nsec = elapsed * sTimebaseInfo.numer / sTimebaseInfo.denom;
+    ts->tv_sec = nsec / 1000000;
+    ts->tv_nsec = nsec % 1000000;
+}
+#   else
+class Timer {
+private:
+    struct timespec state;
+    int conv(const struct timespec& cur)
+    {
+        return (cur.tv_sec - state.tv_sec) * 1000L + (cur.tv_nsec - state.tv_nsec) / 1000000L;
+    }
+public:
+    Timer() {
+        start();
+    }
+    int start() {
+        struct timespec cur;
+        (void) clock_gettime(CLOCK_MONOTONIC, &cur);
+        int ret = conv(cur);
+        state = cur;
+        return ret;
+    }
+    int elapsed() {
+        struct timespec cur;
+        (void) clock_gettime(CLOCK_MONOTONIC, &cur);
+        return conv(cur);
+    }
+};
+#   endif
+#endif