extreme refactoring

[chaz/yoink] / src / Moof / Timer.cc

diff --git a/src/Moof/Timer.cc b/src/Moof/Timer.cc
new file mode 100644 (file)
index 0000000..4eea488
--- /dev/null
+++ b/src/Moof/Timer.cc
@@ -0,0 +1,119 @@
+
+/*******************************************************************************
+
+ Copyright (c) 2009, Charles McGarvey
+ All rights reserved.
+ 
+ Redistribution   and   use  in  source  and  binary  forms,  with  or  without
+ modification, are permitted provided that the following conditions are met:
+ 
+   * Redistributions  of  source  code  must retain the above copyright notice,
+     this list of conditions and the following disclaimer.
+   * Redistributions  in binary form must reproduce the above copyright notice,
+     this  list of conditions and the following disclaimer in the documentation
+     and/or other materials provided with the distribution.
+ 
+ THIS  SOFTWARE  IS  PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND  ANY  EXPRESS  OR  IMPLIED  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED.  IN  NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR  ANY  DIRECT,  INDIRECT,  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES  (INCLUDING,  BUT  NOT  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES;  LOSS  OF  USE,  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED  AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR  TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+*******************************************************************************/
+
+#include <cerrno>
+#include <ctime>
+#include <stdexcept>
+
+#include "Timer.hh"
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+
+namespace Mf {
+
+
+#if HAVE_CLOCK_GETTIME
+
+// Since the monotonic clock will provide us with the timer since the computer
+// started, the number of seconds since that time could easily become so large
+// that it cannot be accurately stored in a float (even with as little two days
+// uptime), therefore we need to start from a more recent reference (when the
+// program starts).  Of course this isn't much of an issue if scalar is a
+// double-precision number.
+
+static time_t setReference_()
+{
+       struct timespec ts;
+
+       if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
+       {
+               return 0;
+       }
+
+       return ts.tv_sec;
+}
+
+static const time_t reference = setReference_();
+
+
+Scalar getTicks()
+{
+       struct timespec ts;
+
+       if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
+       {
+               throw std::runtime_error("cannot access monotonic clock");
+       }
+
+       return Scalar(ts.tv_sec - reference) + Scalar(ts.tv_nsec) / 1000000000.0;
+}
+
+
+#else // ! HAVE_CLOCK_GETTIME
+
+
+// If we don't have posix timers, we'll have to use a different timing method.
+// SDL only promises centisecond accuracy, but that's better than a kick in the
+// butt.
+
+#include <SDL/SDL.h>
+
+Scalar getTicks()
+{
+       Uint32 ms = SDL_GetTicks();
+       return Scalar(ms / 1000) + Scalar(ms % 1000) / 1000.0;
+}
+
+
+#endif // HAVE_CLOCK_GETTIME
+
+
+void sleep(Scalar seconds, bool absolute)
+{
+       struct timespec ts;
+       int ret;
+
+       if (absolute) seconds -= getTicks();
+       ts.tv_sec = time_t(seconds);
+       ts.tv_nsec = long((seconds - Scalar(ts.tv_sec)) * 1000000000.0);
+
+       do
+       {
+               ret = nanosleep(&ts, &ts);
+       }
+       while (ret == -1 && errno == EINTR);
+}
+
+
+} // namespace Mf
+
+/** vim: set ts=4 sw=4 tw=80: *************************************************/
+