From 97b31a97d19884ee92f686321181d34f01c501b3 Mon Sep 17 00:00:00 2001
From: Lephenixnoir <sebastien.michelland@protonmail.com>
Date: Sat, 18 Sep 2021 23:21:40 +0200
Subject: [PATCH] Rate-limit the game at 35 tics/s (17.5 FPS by default)

---
 cgdoom/hu_stuff.c |  2 +-
 cgdoom/i_system.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/cgdoom/hu_stuff.c b/cgdoom/hu_stuff.c
index d867302..0c27d23 100644
--- a/cgdoom/hu_stuff.c
+++ b/cgdoom/hu_stuff.c
@@ -232,7 +232,7 @@ void HU_Start(void)
 
   /* CGDoom: Create the FPS counter widget */
   HUlib_initSText(&w_fpscounter,
-    SCREENWIDTH-48, HU_MSGY, HU_MSGHEIGHT,
+    SCREENWIDTH-44, HU_MSGY, HU_MSGHEIGHT,
     hu_font,
     HU_FONTSTART, &fpscounter_on);
 
diff --git a/cgdoom/i_system.c b/cgdoom/i_system.c
index 0e90d6b..32a68d8 100644
--- a/cgdoom/i_system.c
+++ b/cgdoom/i_system.c
@@ -245,6 +245,28 @@ void I_StartTic (void)
 {
     extern int giRefreshMask;
 
+    //---
+    // Rate limiter
+    //---
+
+    static boolean ratelimit_started = false;
+    static prof_t ratelimit_ctx = prof_make();
+
+    /* Rate limit the game at 35 tics per second, but only extend tics where we
+       display frames, because that's when all the work is done */
+    if(!(gametic & giRefreshMask)) {
+        if(ratelimit_started) {
+            while(1) {
+                prof_t temp = ratelimit_ctx;
+                prof_leave(temp);
+                if(prof_time(temp) >= 28571 * (giRefreshMask + 1)) break;
+            }
+            ratelimit_ctx = prof_make();
+        }
+        prof_enter(ratelimit_ctx);
+        ratelimit_started = true;
+    }
+
     //---
     // FPS counter
     //---