From 15131a1cc20e6e1715113f51c334b221f00c34a8 Mon Sep 17 00:00:00 2001
From: Fabian Greffrath <fabian@greffrath.com>
Date: Mon, 23 Dec 2019 13:12:29 +0100
Subject: [PATCH] let the CPU sleep for 1 ms if there is no tic to proceed

This brings CPU usage down from 100% to ~18% on my system - just like
Chocolate Doom.
---
 Source/d_net.c    | 1 +
 Source/i_system.c | 5 +++++
 Source/i_video.h  | 1 +
 3 files changed, 7 insertions(+)

diff --git a/Source/d_net.c b/Source/d_net.c
index c9989998..48e78423 100644
--- a/Source/d_net.c
+++ b/Source/d_net.c
@@ -758,6 +758,7 @@ void TryRunTics (void)
       M_Ticker ();
       return;
     } 
+    I_Sleep(1);
   }
   
   // run the count * ticdup dics
diff --git a/Source/i_system.c b/Source/i_system.c
index 952dabf6..c72b7689 100644
--- a/Source/i_system.c
+++ b/Source/i_system.c
@@ -59,6 +59,11 @@ void I_WaitVBL(int count)
    SDL_Delay((count*500)/TICRATE);
 }
 
+void I_Sleep(int ms)
+{
+    SDL_Delay(ms);
+}
+
 // Most of the following has been rewritten by Lee Killough
 //
 // I_GetTime
diff --git a/Source/i_video.h b/Source/i_video.h
index 388267aa..1ec81d34 100644
--- a/Source/i_video.h
+++ b/Source/i_video.h
@@ -47,6 +47,7 @@ void I_FinishUpdate (void);
 
 // Wait for vertical retrace or pause a bit.
 void I_WaitVBL(int count);
+void I_Sleep(int ms);
 
 void I_ReadScreen (byte* scr);