N3DS port (squashed)

A dedicated renderer using Citro3D would likely allow for better
much better graphical performances.

src/main/n3ds/SDL_n3ds_main.c

@@ -0,0 +1,82 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "../../SDL_internal.h"
+
+#ifdef __3DS__
+
+#include "SDL_main.h"
+#include <3ds.h>
+
+#ifdef main
+#undef main
+#endif
+
+SDL_FORCE_INLINE void N3DS_Init(void);
+SDL_FORCE_INLINE void N3DS_SetCPUSpeed(void);
+SDL_FORCE_INLINE void N3DS_Quit(void);
+
+#define HIGH_CLOCK 1
+#define L2_CACHE   2
+
+int
+main(int argc, char *argv[])
+{
+    int result;
+    N3DS_Init();
+    SDL_SetMainReady();
+    result = SDL_main(argc, argv);
+    N3DS_Quit();
+    return result;
+}
+
+SDL_FORCE_INLINE void
+N3DS_Init(void)
+{
+    N3DS_SetCPUSpeed();
+    romfsInit();
+    gfxInit(GSP_RGBA8_OES, GSP_RGBA8_OES, false);
+    hidInit();
+}
+
+/* If available, enable L2 cache and high CPU clock */
+SDL_FORCE_INLINE void
+N3DS_SetCPUSpeed(void)
+{
+    if (R_SUCCEEDED(ptmSysmInit())) {
+        if (R_SUCCEEDED(PTMSYSM_CheckNew3DS())) {
+            PTMSYSM_ConfigureNew3DSCPU(HIGH_CLOCK | L2_CACHE);
+        }
+        ptmSysmExit();
+    }
+}
+
+SDL_FORCE_INLINE void
+N3DS_Quit(void)
+{
+    hidExit();
+    gfxExit();
+    romfsExit();
+}
+
+#endif /* __3DS__ */
+
+/* vi: set sts=4 ts=4 sw=4 expandtab: */