Convert the half sleep to a sleep that is a fraction of the target FPS (Default 95%) to reduce CPU use. (#1756)

Co-authored-by: Jeffery Myers <JefMyers@blizzard.com>

src/config.h

@@ -43,8 +43,8 @@
 #define SUPPORT_WINMM_HIGHRES_TIMER 1
 // Use busy wait loop for timing sync, if not defined, a high-resolution timer is setup and used
 //#define SUPPORT_BUSY_WAIT_LOOP      1
-// Use a half-busy wait loop, in this case frame sleeps for some time and runs a busy-wait-loop at the end
-#define SUPPORT_HALFBUSY_WAIT_LOOP
+// Use a partial-busy wait loop, in this case frame sleeps for most of the time, but then runs a busy loop at the end for accuracy
+#define SUPPORT_PARTIALBUSY_WAIT_LOOP
 // Wait for events passively (sleeping while no events) instead of polling them actively every frame
 //#define SUPPORT_EVENTS_WAITING      1
 // Allow automatic screen capture of current screen pressing F12, defined in KeyCallback()

src/core.c

@@ -62,8 +62,8 @@
 *   #define SUPPORT_BUSY_WAIT_LOOP
 *       Use busy wait loop for timing sync, if not defined, a high-resolution timer is setup and used
 *
-*   #define SUPPORT_HALFBUSY_WAIT_LOOP
-*       Use a half-busy wait loop, in this case frame sleeps for some time and runs a busy-wait-loop at the end
+*   #define SUPPORT_PARTIALBUSY_WAIT_LOOP
+*       Use a partial-busy wait loop, in this case frame sleeps for most of the time and runs a busy-wait-loop at the end
 *
 *   #define SUPPORT_EVENTS_WAITING
 *       Wait for events passively (sleeping while no events) instead of polling them actively every frame
@@ -4550,10 +4550,15 @@ static void Wait(float ms)
     // Busy wait loop
     while ((nextTime - prevTime) < ms/1000.0f) nextTime = GetTime();
 #else
-    #if defined(SUPPORT_HALFBUSY_WAIT_LOOP)
-        #define MAX_HALFBUSY_WAIT_TIME  4
+    #if defined(SUPPORT_PARTIALBUSY_WAIT_LOOP)
+        #define DEFAULT_PARTIALBUSY_WAIT_TIME  4
+        #define PARTIALBUSY_WAIT_FACTOR 0.95f
+        float halfWait = DEFAULT_PARTIALBUSY_WAIT_TIME;
+        if (CORE.Time.target > 0)
+            halfWait = CORE.Time.target * PARTIALBUSY_WAIT_FACTOR;
+
         double destTime = GetTime() + ms/1000;
-        if (ms > MAX_HALFBUSY_WAIT_TIME) ms -= MAX_HALFBUSY_WAIT_TIME;
+        if (ms > halfWait) ms -= halfWait;
     #endif
 
     #if defined(_WIN32)
@@ -4573,7 +4578,7 @@ static void Wait(float ms)
         usleep(ms*1000.0f);
     #endif
 
-    #if defined(SUPPORT_HALFBUSY_WAIT_LOOP)
+    #if defined(SUPPORT_PARTIALBUSY_WAIT_LOOP)
         while (GetTime() < destTime) { }
     #endif
 #endif