Merge pull request #97 from rickgaiser/hires_ratelimit

Add fps rate limiter

Author: fjtrujy

CMakeLists.txt

@@ -165,6 +165,7 @@ add_object_library_macros(GS_HIRES_OBJS ee/gs/src/gsHires.c
 	_gsKit_create_passes
 	gsKit_hires_sync
 	gsKit_hires_flip
+	gsKit_hires_flip_ext
 	gsKit_hires_prepare_bg
 	gsKit_hires_set_bg
 	gsKit_hires_init_screen

ee/gs/include/gsCore.h

@@ -82,6 +82,14 @@ struct gsVertex
 };
 typedef struct gsVertex GSVERTEX;
 
+/// Flip mode for gsKit_hires_flip_ext
+typedef enum {
+    GSFLIP_DIRECT = 0,       ///< Flip immediately, no vsync wait
+    GSFLIP_VSYNC = 1,        ///< Wait for vsync before flipping
+    GSFLIP_RATE_LIMIT_1 = 2, ///< Limit to 60fps (1 vsync per frame)
+    GSFLIP_RATE_LIMIT_2 = 3  ///< Limit to 30fps (2 vsyncs per frame)
+} GSFLIP_MODE;
+
 #ifdef __cplusplus
 extern "C" {
 #endif

ee/gs/include/gsHires.h

@@ -28,6 +28,9 @@ void gsKit_hires_sync(GSGLOBAL *gsGlobal);
 /// Flips Draw Queue
 void gsKit_hires_flip(GSGLOBAL *gsGlobal);
 
+/// Flips Draw Queue with specified flip mode
+void gsKit_hires_flip_ext(GSGLOBAL *gsGlobal, GSFLIP_MODE mode);
+
 /// Converts PSM and interlacing for use as background image
 void gsKit_hires_prepare_bg(GSGLOBAL *gsGlobal, GSTEXTURE * tex);
 

ee/gs/src/gsHires.c

@@ -260,8 +260,35 @@ void gsKit_hires_sync(GSGLOBAL *gsGlobal)
 
 #if F_gsKit_hires_flip
 void gsKit_hires_flip(GSGLOBAL *gsGlobal)
+{
+	gsKit_hires_flip_ext(gsGlobal, GSFLIP_DIRECT);
+}
+#endif
+
+#if F_gsKit_hires_flip_ext
+// State tracking for rate limiting
+static u32 __last_flip_vsync_count = 0;
+
+void gsKit_hires_flip_ext(GSGLOBAL *gsGlobal, GSFLIP_MODE mode)
 {
 	u32 iY;
+	u32 vsync_end;
+
+	// Handle vsync waiting based on mode
+	switch (mode) {
+		case GSFLIP_DIRECT:       vsync_end = __vsync_count; break;
+		case GSFLIP_VSYNC:        vsync_end = __vsync_count + 1; break;
+		case GSFLIP_RATE_LIMIT_1: vsync_end = __last_flip_vsync_count + 1; break;
+		case GSFLIP_RATE_LIMIT_2: vsync_end = __last_flip_vsync_count + 2; break;
+	}
+
+	// Wait for required vsyncs
+	while (__vsync_count < vsync_end) {
+		WaitSema(__sema_vsync_id);
+	}
+
+	// Update last flip vsync count
+	__last_flip_vsync_count = __vsync_count;
 
 	// HACK: The start of the first displayed line
 	// this is needed by the hsync interrupt but must be