Remove `(un)lock_buf`

We do not seem to render from multiple threads, so these calls are
unnecessary.

Source/capture.cpp

@@ -169,7 +169,6 @@ void CaptureScreen()
 	PaletteGetEntries(256, palette);
 	RedPalette();
 
-	lock_buf(2);
 	const Surface &buf = GlobalBackBuffer();
 	success = CaptureHdr(buf.w(), buf.h(), &outStream);
 	if (success) {
@@ -178,7 +177,6 @@ void CaptureScreen()
 	if (success) {
 		success = CapturePal(palette, &outStream);
 	}
-	unlock_buf(2);
 	outStream.close();
 
 	if (!success) {

Source/dx.cpp

@@ -13,7 +13,6 @@
 #include "options.h"
 #include "utils/display.h"
 #include "utils/log.hpp"
-#include "utils/sdl_mutex.h"
 #include "utils/sdl_wrap.h"
 
 #ifdef __3DS__
@@ -46,12 +45,6 @@ bool RenderDirectlyToOutputSurface;
 
 namespace {
 
-int sgdwLockCount;
-#ifdef _DEBUG
-int locktbl[256];
-#endif
-SdlMutex MemCrit;
-
 bool CanRenderDirectlyToOutputSurface()
 {
 #ifdef USE_SDL1
@@ -68,26 +61,6 @@ bool CanRenderDirectlyToOutputSurface()
 #endif
 }
 
-void LockBufPriv()
-{
-	MemCrit.lock();
-	if (sgdwLockCount != 0) {
-		sgdwLockCount++;
-		return;
-	}
-
-	sgdwLockCount++;
-}
-
-void UnlockBufPriv()
-{
-	if (sgdwLockCount == 0)
-		app_fatal("draw main unlock error");
-
-	sgdwLockCount--;
-	MemCrit.unlock();
-}
-
 /**
  * @brief Limit FPS to avoid high CPU load, use when v-sync isn't available
  */
@@ -119,31 +92,8 @@ void dx_init()
 	pal_surface_palette_version = 1;
 }
 
-void lock_buf(int idx) // NOLINT(misc-unused-parameters)
-{
-#ifdef _DEBUG
-	++locktbl[idx];
-#endif
-	LockBufPriv();
-}
-
-void unlock_buf(int idx) // NOLINT(misc-unused-parameters)
-{
-#ifdef _DEBUG
-	if (locktbl[idx] == 0)
-		app_fatal("Draw lock underflow: 0x%x", idx);
-	--locktbl[idx];
-#endif
-	UnlockBufPriv();
-}
-
 Surface GlobalBackBuffer()
 {
-	if (sgdwLockCount == 0) {
-		Log("WARNING: Trying to obtain GlobalBackBuffer() without holding a lock");
-		return Surface();
-	}
-
 	return Surface(PalSurface, SDL_Rect { 0, 0, gnScreenWidth, gnScreenHeight });
 }
 
@@ -153,9 +103,6 @@ void dx_cleanup()
 	if (ghMainWnd != nullptr)
 		SDL_HideWindow(ghMainWnd);
 #endif
-	MemCrit.lock();
-	sgdwLockCount = 0;
-	MemCrit.unlock();
 
 	PalSurface = nullptr;
 	PinnedPalSurface = nullptr;

Source/dx.h

@@ -15,8 +15,6 @@ extern bool RenderDirectlyToOutputSurface;
 Surface GlobalBackBuffer();
 
 void dx_init();
-void lock_buf(int idx);
-void unlock_buf(int idx);
 void dx_cleanup();
 void CreateBackBuffer();
 void InitPalette();

Source/interfac.cpp

@@ -170,7 +170,6 @@ void InitCutscene(interface_mode uMsg)
 
 void DrawCutscene()
 {
-	lock_buf(1);
 	const Surface &out = GlobalBackBuffer();
 	DrawArt(out, { PANEL_X - (ArtCutsceneWidescreen.w() - PANEL_WIDTH) / 2, UI_OFFSET_Y }, &ArtCutsceneWidescreen);
 	CelDrawTo(out, { PANEL_X, 480 - 1 + UI_OFFSET_Y }, *sgpBackCel, 1);
@@ -183,8 +182,6 @@ void DrawCutscene()
 	    ProgressHeight);
 	SDL_FillRect(out.surface, &rect, BarColor[progress_id]);
 
-	unlock_buf(1);
-
 	BltFast(&rect, &rect);
 	RenderPresent();
 }

Source/scrollrt.cpp

@@ -1564,12 +1564,8 @@ extern SDL_Surface *PalSurface;
 
 void ClearScreenBuffer()
 {
-	lock_buf(3);
-
 	assert(PalSurface != nullptr);
 	SDL_FillRect(PalSurface, nullptr, 0);
-
-	unlock_buf(3);
 }
 
 #ifdef _DEBUG
@@ -1670,9 +1666,7 @@ void scrollrt_draw_game_screen()
 	if (IsHardwareCursor()) {
 		SetHardwareCursorVisible(ShouldShowCursor());
 	} else {
-		lock_buf(0);
 		DrawCursor(GlobalBackBuffer());
-		unlock_buf(0);
 	}
 
 	DrawMain(hgt, false, false, false, false, false);
@@ -1680,9 +1674,7 @@ void scrollrt_draw_game_screen()
 	RenderPresent();
 
 	if (!IsHardwareCursor()) {
-		lock_buf(0);
 		UndrawCursor(GlobalBackBuffer());
-		unlock_buf(0);
 	}
 }
 
@@ -1712,7 +1704,6 @@ void DrawAndBlit()
 
 	force_redraw = 0;
 
-	lock_buf(0);
 	const Surface &out = GlobalBackBuffer();
 	UndrawCursor(out);
 
@@ -1754,8 +1745,6 @@ void DrawAndBlit()
 
 	DrawFPS(out);
 
-	unlock_buf(0);
-
 	DrawMain(hgt, ddsdesc, drawhpflag, drawmanaflag, drawsbarflag, drawbtnflag);
 
 	RenderPresent();