160 lines
4.1 KiB
C
160 lines
4.1 KiB
C
// BLANKART
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//-----------------------------------------------------------------------------
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// Copyright (C) 1993-1996 by id Software, Inc.
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// Copyright (C) 1998-2000 by DooM Legacy Team.
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// Copyright (C) 1999-2022 by Sonic Team Junior.
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//
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// This program is free software distributed under the
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// terms of the GNU General Public License, version 2.
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// See the 'LICENSE' file for more details.
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//-----------------------------------------------------------------------------
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/// \file i_time.c
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/// \brief Timing for the system layer.
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#include "i_time.h"
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#include <math.h>
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#include "command.h"
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#include "doomtype.h"
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#include "d_netcmd.h"
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#include "m_fixed.h"
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#include "i_system.h"
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timestate_t g_time = {};
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static CV_PossibleValue_t timescale_cons_t[] = {{FRACUNIT/20, "MIN"}, {20*FRACUNIT, "MAX"}, {0, NULL}};
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consvar_t cv_timescale = CVAR_INIT ("timescale", "1.0", CV_NETVAR|CV_CHEAT|CV_FLOAT, timescale_cons_t, NULL);
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static precise_t enterprecise, oldenterprecise;
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static fixed_t entertic, oldentertics;
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static double tictimer;
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static double ticratescaled;
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// experiment to prevent timing issues
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// this returns the global time state accounted with how much time has passed
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// since it was last updated
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static void I_GetTimeAndFrac(tic_t *outtics, fixed_t *outfrac)
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{
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double elapsedseconds;
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elapsedseconds = (double)(I_GetPreciseTime() - oldenterprecise) / I_GetPrecisePrecision();
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double fractional, integral;
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fractional = modf((tictimer + elapsedseconds) * ticratescaled, &integral);
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if (outtics)
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*outtics = g_time.time + (tic_t)integral;
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if (outfrac)
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*outfrac = DoubleToFixed(fractional);
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}
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// A little more than the minimum sleep duration on Windows.
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// May be incorrect for other platforms, but we don't currently have a way to
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// query the scheduler granularity. SDL will do what's needed to make this as
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// low as possible though.
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#if defined(_WIN32)
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#define MIN_SLEEP_DURATION_MS 1.6
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#else
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#define MIN_SLEEP_DURATION_MS 2.1
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#endif
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tic_t I_GetTime(void)
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{
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tic_t tic;
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I_GetTimeAndFrac(&tic, NULL);
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return tic;
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}
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fixed_t I_GetTimeFrac(void)
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{
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fixed_t frac;
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I_GetTimeAndFrac(NULL, &frac);
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return frac;
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}
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void I_InitializeTime(void)
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{
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g_time.time = 0;
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g_time.timefrac = 0;
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enterprecise = 0;
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oldenterprecise = 0;
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tictimer = 0.0;
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ticratescaled = 1.0;
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CV_RegisterVar(&cv_timescale);
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// I_StartupTimer is preserved for potential subsystems that need to setup
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// timing information for I_GetPreciseTime and sleeping
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I_StartupTimer();
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}
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void I_UpdateTime(fixed_t timescale)
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{
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double elapsedseconds;
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tic_t realtics;
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// get real tics
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ticratescaled = (double)((float)TICRATE * FixedToFloat(timescale));
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enterprecise = I_GetPreciseTime();
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elapsedseconds = (double)(enterprecise - oldenterprecise) / I_GetPrecisePrecision();
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tictimer += elapsedseconds;
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while (tictimer > 1.0/ticratescaled)
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{
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entertic += 1;
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tictimer -= 1.0/ticratescaled;
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}
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realtics = entertic - oldentertics;
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oldentertics = entertic;
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oldenterprecise = enterprecise;
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// Update global time state
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g_time.time += realtics;
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{
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double fractional, integral;
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fractional = modf(tictimer * ticratescaled, &integral);
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g_time.timefrac = FLOAT_TO_FIXED(fractional);
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}
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}
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void I_SleepDuration(precise_t duration)
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{
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UINT64 precision = I_GetPrecisePrecision();
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INT32 sleepvalue = cv_sleep.value;
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UINT64 delaygranularity;
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precise_t cur;
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precise_t dest;
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{
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double gran = round(((double)(precision / 1000) * sleepvalue * MIN_SLEEP_DURATION_MS));
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delaygranularity = (UINT64)gran;
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}
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cur = I_GetPreciseTime();
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dest = cur + duration;
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// the reason this is not dest > cur is because the precise counter may wrap
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// two's complement arithmetic is our friend here, though!
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// e.g. cur 0xFFFFFFFFFFFFFFFE = -2, dest 0x0000000000000001 = 1
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// 0x0000000000000001 - 0xFFFFFFFFFFFFFFFE = 3
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while ((INT64)(dest - cur) > 0)
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{
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// If our cv_sleep value exceeds the remaining sleep duration, use the
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// hard sleep function.
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if (sleepvalue > 0 && (dest - cur) > delaygranularity)
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{
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#if defined(_WIN32)
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DWORD sleepDuration = (DWORD)min((INT64)(dest - cur), sleepvalue);
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SleepEx(sleepDuration, TRUE);
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#else
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I_Sleep(sleepvalue);
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#endif
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}
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// Otherwise, this is a spinloop.
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cur = I_GetPreciseTime();
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}
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}
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