From 7f414f4946354a3b960b1f6a15cfdad014d7e199 Mon Sep 17 00:00:00 2001
From: Ian C <ianc@noddybox.co.uk>
Date: Thu, 21 May 2020 20:33:44 +0000
Subject: Added timer to control update speed.

---
 README  |  6 ++----
 lunar.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/README b/README
index 3f8f739..3ae25dc 100644
--- a/README
+++ b/README
@@ -23,10 +23,8 @@ Though written under FreeBSD, it should compile OK on most flavours of unix.
 USAGE
 -----
 
-lunar [-noshm] [scale]	- Use scale to magnify and impact overly fast servers.
-			  Use -noshm as well if your server is still too fast
-			  to disable MIT-SHM usage.  (Note shm usage will be
-			  disabled if your server doesn't support it anyway).
+lunar [-noshm] [scale]	- Use scale to magnify the screen.  Use -noshm to
+			  disable MIT_SHM usage if it causes problems.
 
 
 ledit <level_file>
diff --git a/lunar.c b/lunar.c
index f57d899..86d0619 100644
--- a/lunar.c
+++ b/lunar.c
@@ -37,6 +37,7 @@ static char rcs_id[]="$Id$";
 #include <fcntl.h>
 #include <string.h>
 #include <errno.h>
+#include <signal.h>
 
 #include <unistd.h>
 #include <sys/types.h>
@@ -79,6 +80,8 @@ static uchar		*coll_data;
 
 static double		si[3600],co[3600];
 
+static struct timespec	frame_start;
+
 static XFuncControl	Key(Window w, XPressRelease s, XEvent *e);
 static XFuncControl	ProcessTitle(void),ProcessIntro(void),ProcessGame(void),
 			ProcessGameOver(void),ProcessHiScore(void);
@@ -356,6 +359,8 @@ static int	Paused(int k);
 static void	ReadScores(void);
 static void	WriteScores(void);
 static void	ReadLevels(void);
+static void	StartFrame(void);
+static void	EndFrame(void);
 
 
 int main(int argc,char *argv[])
@@ -1164,6 +1169,7 @@ static XFuncControl ProcessTitle(void)
 
     ctr++;
 
+    StartFrame();
     Cls();
 
     for(f=0;f<10;f++)
@@ -1198,6 +1204,7 @@ static XFuncControl ProcessTitle(void)
     DoDebugMenu();
 
     Update();
+    EndFrame();
 
     k=GetKey();
 
@@ -1345,6 +1352,7 @@ static XFuncControl ProcessGame(void)
     if (Paused(k))
 	return XFUNCCONT;
 
+    StartFrame();
     Cls();
 
     /* Process movement
@@ -1471,6 +1479,7 @@ static XFuncControl ProcessGame(void)
 	CheckCollisions(&landed,&dead);
 
     Update();
+    EndFrame();
 
     if (k==SCALE_UP)
     {
@@ -1643,6 +1652,7 @@ static XFuncControl ProcessHiScore(void)
 	first=False;
     }
 
+    StartFrame();
     Cls();
 
     Centre(16,WHITE,"CONGRATULATIONS!");
@@ -1689,6 +1699,7 @@ static XFuncControl ProcessHiScore(void)
 	bounce--;
 
     Update();
+    EndFrame();
 
     if (len==3)
     {
@@ -1860,3 +1871,40 @@ static void ReadLevels(void)
     for(f=0;f<no_levels;f++)
 	free(name[f]);
 }
+
+static void StartFrame(void)
+{
+    clock_gettime(CLOCK_REALTIME, &frame_start);
+}
+
+
+static void EndFrame(void)
+{
+    static const long FRAME = 1000000000 / 25;
+    struct timespec now;
+    struct timespec diff;
+
+    clock_gettime(CLOCK_REALTIME, &now);
+
+    diff.tv_sec = now.tv_sec - frame_start.tv_sec;
+    diff.tv_nsec = now.tv_nsec - frame_start.tv_nsec;
+
+    if (diff.tv_sec > 0)
+    {
+    	diff.tv_sec--;
+	diff.tv_nsec += 1000000000;
+    }
+
+    if (diff.tv_nsec >= 1000000000)
+    {
+    	diff.tv_sec++;
+	diff.tv_nsec -= 1000000000;
+    }
+
+    if (diff.tv_sec == 0 && diff.tv_nsec < FRAME)
+    {
+	diff.tv_nsec = FRAME - diff.tv_nsec;
+
+	nanosleep(&diff, NULL);
+    }
+}
-- 
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