add code for running display at 50Hz

disabled until i know how it runs on 2ds
related to #46

include/main.h

@@ -11,4 +11,6 @@ extern char rom_name[128];
 
 extern bool game_running;
 
+void frame_pacer_thread();
+
 #endif

include/periodic.h

@@ -3,5 +3,6 @@
 typedef void (*threadfunc_t)();
 
 bool startPeriodic(threadfunc_t func, int periodNanos);
+bool startPeriodicVsync(threadfunc_t func);
 void endThread(threadfunc_t func);
 void endThreads();

include/vb_gui.h

@@ -61,6 +61,7 @@ void showError(int code);
 extern Thread save_thread;
 
 bool guiShouldPause();
+void toggleVsync(bool enable);
 void aptBacklight(APT_HookType hook, void* param);
 int guiGetInput(bool do_switching);
 

include/vb_set.h

@@ -78,6 +78,7 @@ typedef struct VB_OPT {
     char *PROG_NAME; // Path\Name of program
     unsigned long CRC32; // CRC32 of ROM
     bool  PERF_INFO;
+    bool  VSYNC;
 } VB_OPT;
 
 void setDefaults(void);

source/3ds/gui_hard.c

@@ -13,6 +13,7 @@
 #include "vb_types.h"
 #include "replay.h"
 #include "main.h"
+#include "periodic.h"
 #include "sprites_t3x.h"
 #include "sprites.h"
 
@@ -1340,8 +1341,36 @@ bool toggleBacklight(bool enable) {
     return enable;
 }
 
+void toggleVsync(bool enable) {
+    endThread(frame_pacer_thread);
+    u32 vtotal_top, vtotal_bottom;
+    if (enable) {
+        // 990 is closer to 50Hz but capture cards don't like when the two screens are out of sync
+        vtotal_top = 989;
+        vtotal_bottom = 494;
+        startPeriodicVsync(frame_pacer_thread);
+    } else {
+        vtotal_top = 827;
+        vtotal_bottom = 413;
+        startPeriodic(frame_pacer_thread, 20000000);
+    }
+    GSPGPU_WriteHWRegs(0x400424, &vtotal_top, 4);
+    GSPGPU_WriteHWRegs(0x400524, &vtotal_bottom, 4);
+}
+
 void aptBacklight(APT_HookType hook, void* param) {
-    if (backlightEnabled == false) {
+    if (tVBOpt.VSYNC) {
+        switch (hook) {
+            case APTHOOK_ONRESTORE:
+            case APTHOOK_ONWAKEUP:
+                toggleVsync(true);
+                break;
+            default:
+                toggleVsync(false);
+                break;
+        }
+    }
+    if (!backlightEnabled) {
         switch (hook) {
             case APTHOOK_ONRESTORE:
             case APTHOOK_ONWAKEUP:

source/3ds/main.c

@@ -15,6 +15,7 @@
 #include "vb_gui.h"
 #include "rom_db.h"
 #include "replay.h"
+#include "utils.h"
 
 char rom_path[256] = "sdmc:/vb/";
 char rom_name[128];
@@ -60,6 +61,10 @@ int main() {
 
     drc_init();
 
+    if (is_citra) {
+        tVBOpt.VSYNC = false;
+    }
+
     replay_init();
 
     guiop = 0;
@@ -76,7 +81,8 @@ int main() {
     osSetSpeedupEnable(true);
 
     svcCreateEvent(&frame_event, RESET_STICKY);
-    startPeriodic(frame_pacer_thread, 20000000);
+
+    toggleVsync(tVBOpt.VSYNC);
 
     TickCounter drcTickCounter;
     TickCounter frameTickCounter;
@@ -202,6 +208,7 @@ int main() {
     save_sram();
 
 exit:
+    toggleVsync(false);
     sound_close();
     if (save_thread) threadJoin(save_thread, U64_MAX);
     endThreads();

source/3ds/periodic.c

@@ -36,6 +36,18 @@ static void periodic(void *periodArgs_v) {
     svcCloseHandle(timer);
 }
 
+static void periodic_vsync(void *periodArgs_v) {
+    PeriodArgs *periodArgs = (PeriodArgs*)periodArgs_v;
+    threadfunc_t func = periodArgs->func;
+    int id = periodArgs->id;
+    svcSignalEvent(periodArgs->readyEvent);
+
+    while (threadrunning[id]) {
+        gspWaitForVBlank();
+        func();
+    }
+}
+
 bool startPeriodic(threadfunc_t func, int periodNanos) {
     PeriodArgs periodArgs;
     periodArgs.func = func;
@@ -59,6 +71,28 @@ bool startPeriodic(threadfunc_t func, int periodNanos) {
     return false;
 }
 
+bool startPeriodicVsync(threadfunc_t func) {
+    PeriodArgs periodArgs;
+    periodArgs.func = func;
+    svcCreateEvent(&periodArgs.readyEvent, RESET_ONESHOT);
+    for (int i = 0; i < THREAD_COUNT; i++) {
+        if (!threadrunning[i]) {
+            periodArgs.id = i;
+            threadfuncs[i] = func;
+            threadrunning[i] = true;
+            threads[i] = threadCreate(periodic_vsync, &periodArgs, 4000, 0x18, 0, true);
+            if (!threads[i]) {
+                threadrunning[i] = false;
+                return false;
+            }
+            svcWaitSynchronization(periodArgs.readyEvent, 0);
+            svcCloseHandle(periodArgs.readyEvent);
+            return true;
+        }
+    }
+    return false;
+}
+
 void endThread(threadfunc_t func) {
     for (int i = 0; i < THREAD_COUNT; i++) {
         if (threadrunning[i] && threadfuncs[i] == func) {

source/3ds/video.c

@@ -204,6 +204,9 @@ void video_init() {
 	C3D_RenderTargetClear(finalScreen[0], C3D_CLEAR_COLOR, 0, 0);
 	C3D_FrameEnd(0);
 	gspWaitForVBlank();
+
+	u32 vtotal = 990;
+	GSPGPU_WriteHWRegs(0x400424, &vtotal, 4);
 }
 
 void video_render(int alt_buf) {

source/common/vb_set.c

@@ -47,6 +47,7 @@ void setDefaults(void) {
     tVBOpt.DEFAULT_EYE = 0;
     tVBOpt.PERF_INFO = false;
     tVBOpt.ROM_PATH = NULL;
+    tVBOpt.VSYNC = false;
 
     // Default keys
 #ifdef __3DS__