From 84ce53db60bce109fe87a895d5341ac3f7cd0673 Mon Sep 17 00:00:00 2001
From: James R <justsomejames2@gmail.com>
Date: Sat, 7 Nov 2020 01:31:24 -0800
Subject: [PATCH] Use high precision timer, replace I_GetTimeMicros with
I_GetPreciseTime and I_PreciseToMicros
---
src/doomtype.h | 4 ++++
src/i_system.h | 8 +++++++-
src/sdl/i_system.c | 33 ++++++++++++---------------------
3 files changed, 23 insertions(+), 22 deletions(-)
diff --git a/src/doomtype.h b/src/doomtype.h
index 4e13ba96d3..c239c7b8e9 100644
--- a/src/doomtype.h
+++ b/src/doomtype.h
@@ -379,4 +379,8 @@ Needed for some lua shenanigans.
#define FIELDFROM( type, field, have, want ) \
(void *)((intptr_t)(field) - offsetof (type, have) + offsetof (type, want))
+#ifdef HAVE_SDL
+typedef UINT64 precise_t;
+#endif
+
#endif //__DOOMTYPE__
diff --git a/src/i_system.h b/src/i_system.h
index dd0b65f6df..12f0d751d1 100644
--- a/src/i_system.h
+++ b/src/i_system.h
@@ -46,7 +46,13 @@ UINT32 I_GetFreeMem(UINT32 *total);
*/
tic_t I_GetTime(void);
-int I_GetTimeMicros(void);// provides microsecond counter for render stats
+/** \brief Returns precise time value for performance measurement.
+ */
+precise_t I_GetPreciseTime(void);
+
+/** \brief Returns the difference between precise times as microseconds.
+ */
+int I_PreciseToMicros(precise_t);
/** \brief The I_Sleep function
diff --git a/src/sdl/i_system.c b/src/sdl/i_system.c
index 70ae938e93..8a70847e1e 100644
--- a/src/sdl/i_system.c
+++ b/src/sdl/i_system.c
@@ -54,8 +54,6 @@ typedef LPVOID (WINAPI *p_MapViewOfFile) (HANDLE, DWORD, DWORD, DWORD, SIZE_T);
#include <fcntl.h>
#endif
-int TimeFunction(int requested_frequency);
-
#include <stdio.h>
#ifdef _WIN32
#include <conio.h>
@@ -2045,32 +2043,23 @@ ticcmd_t *I_BaseTiccmd2(void)
// returns time in 1/TICRATE second tics
//
-// millisecond precision only
-int TimeFunction(int requested_frequency)
-{
- static Uint64 basetime = 0;
- Uint64 ticks = SDL_GetTicks();
-
- if (!basetime)
- basetime = ticks;
-
- ticks -= basetime;
-
- ticks = (ticks*requested_frequency);
+static Uint64 timer_frequency;
+static Uint64 tic_epoch;
- ticks = (ticks/1000);
-
- return ticks;
+tic_t I_GetTime(void)
+{
+ const Uint64 now = SDL_GetPerformanceCounter();
+ return (now - tic_epoch) * NEWTICRATE / timer_frequency;
}
-tic_t I_GetTime(void)
+precise_t I_GetPreciseTime(void)
{
- return TimeFunction(NEWTICRATE);
+ return SDL_GetPerformanceCounter();
}
-int I_GetTimeMicros(void)
+int I_PreciseToMicros(precise_t d)
{
- return TimeFunction(1000000);
+ return d / (timer_frequency / 1000000);
}
//
@@ -2078,6 +2067,8 @@ int I_GetTimeMicros(void)
//
void I_StartupTimer(void)
{
+ timer_frequency = SDL_GetPerformanceFrequency();
+ tic_epoch = SDL_GetPerformanceCounter();
}
void I_Sleep(void)
--
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