- fixed compilation in debug mode.

- moved timer definitions into their own header/source files. d_main is not the right place for this.
- removed some leftover cruft from the old timer code.

src/i_time.cpp

@@ -0,0 +1,161 @@
+/*
+** i_time.cpp
+** Implements the timer
+**
+**---------------------------------------------------------------------------
+** Copyright 1998-2916 Randy Heit
+** Copyright 2917 Magnus Norddahl
+** All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions
+** are met:
+**
+** 1. Redistributions of source code must retain the above copyright
+**    notice, this list of conditions and the following disclaimer.
+** 2. 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.
+** 3. The name of the author may not be used to endorse or promote products
+**    derived from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 <chrono>
+#include <thread>
+#include <stdint.h>
+#include "i_time.h"
+#include "doomdef.h"
+
+//==========================================================================
+//
+// Tick time functions
+//
+//==========================================================================
+
+static unsigned int FirstFrameStartTime;
+static unsigned int CurrentFrameStartTime;
+static unsigned int FreezeTime;
+
+static uint32_t performanceGetTime()
+{
+	using namespace std::chrono;
+	return (uint32_t)duration_cast<milliseconds>(steady_clock::now().time_since_epoch()).count();
+}
+
+void I_SetFrameTime()
+{
+	// Must only be called once per frame/swapbuffers.
+	//
+	// Caches all timing information for the current rendered frame so that any
+	// calls to I_FPSTime, I_MSTime, I_GetTime or I_GetTimeFrac will return
+	// the same time.
+
+	if (FreezeTime == 0)
+	{
+		CurrentFrameStartTime = performanceGetTime();
+		if (FirstFrameStartTime == 0)
+			FirstFrameStartTime = CurrentFrameStartTime;
+	}
+}
+
+void I_WaitVBL(int count)
+{
+	// I_WaitVBL is never used to actually synchronize to the vertical blank.
+	// Instead, it's used for delay purposes. Doom used a 70 Hz display mode,
+	// so that's what we use to determine how long to wait for.
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(1000 * count / 70));
+	I_SetFrameTime();
+}
+
+int I_WaitForTic(int prevtic)
+{
+	// Waits until the current tic is greater than prevtic. Time must not be frozen.
+
+	int time;
+	while ((time = I_GetTime()) <= prevtic)
+	{
+		// The minimum amount of time a thread can sleep is controlled by timeBeginPeriod.
+		// We set this to 1 ms in DoMain.
+		int sleepTime = prevtic - time;
+		if (sleepTime > 2)
+			std::this_thread::sleep_for(std::chrono::milliseconds(sleepTime - 2));
+
+		I_SetFrameTime();
+	}
+
+	return time;
+}
+
+unsigned int I_FPSTime()
+{
+	if (FreezeTime == 0)
+		return CurrentFrameStartTime;
+	else
+		return performanceGetTime();
+}
+
+unsigned int I_MSTime()
+{
+	if (FreezeTime == 0)
+	{
+		return CurrentFrameStartTime - FirstFrameStartTime;
+	}
+	else
+	{
+		if (FirstFrameStartTime == 0)
+		{
+			FirstFrameStartTime = performanceGetTime();
+			return 0;
+		}
+		else
+		{
+			return performanceGetTime() - FirstFrameStartTime;
+		}
+	}
+}
+
+int I_GetTime()
+{
+	return (CurrentFrameStartTime - FirstFrameStartTime) * TICRATE / 1000 + 1;
+}
+
+double I_GetTimeFrac(uint32_t *ms)
+{
+	unsigned int currentTic = (CurrentFrameStartTime - FirstFrameStartTime) * TICRATE / 1000;
+	unsigned int ticStartTime = FirstFrameStartTime + currentTic * 1000 / TICRATE;
+	unsigned int ticNextTime = FirstFrameStartTime + (currentTic + 1) * 1000 / TICRATE;
+
+	if (ms)
+		*ms = currentTic + 1;
+
+	return (CurrentFrameStartTime - ticStartTime) / (double)(ticNextTime - ticStartTime);
+}
+
+void I_FreezeTime(bool frozen)
+{
+	if (frozen)
+	{
+		FreezeTime = performanceGetTime();
+	}
+	else
+	{
+		FirstFrameStartTime += performanceGetTime() - FreezeTime;
+		FreezeTime = 0;
+		I_SetFrameTime();
+	}
+}
+