N3DS port (squashed)

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

src/filesystem/n3ds/SDL_sysfilesystem.c

@@ -0,0 +1,86 @@
+/*
+  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 SDL_FILESYSTEM_N3DS
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+/* System dependent filesystem routines                                */
+
+#include <3ds.h>
+#include <dirent.h>
+#include <errno.h>
+
+#include "SDL_error.h"
+#include "SDL_filesystem.h"
+
+SDL_FORCE_INLINE char *MakePrefPath(const char *app);
+SDL_FORCE_INLINE int CreatePrefPathDir(const char *pref);
+
+char *
+SDL_GetBasePath(void)
+{
+    char *base_path = SDL_strdup("romfs:/");
+    return base_path;
+}
+
+char *
+SDL_GetPrefPath(const char *org, const char *app)
+{
+    char *pref_path = NULL;
+    if (app == NULL) {
+        SDL_InvalidParamError("app");
+        return NULL;
+    }
+
+    pref_path = MakePrefPath(app);
+    if (CreatePrefPathDir(pref_path) < 0) {
+        SDL_free(pref_path);
+        return NULL;
+    }
+
+    return pref_path;
+}
+
+SDL_FORCE_INLINE char *
+MakePrefPath(const char *app)
+{
+    static const char *FMT = "/3ds/%s/";
+    size_t length = SDL_snprintf(NULL, 0, FMT, app) + 1;
+    char *pref_path = (char *) SDL_calloc(length, sizeof(char));
+    SDL_snprintf(pref_path, length, FMT, app);
+    return pref_path;
+}
+
+SDL_FORCE_INLINE int
+CreatePrefPathDir(const char *pref)
+{
+    int result = mkdir(pref, 0666);
+
+    if (result == -1 && errno != EEXIST) {
+        return SDL_SetError("Failed to create '%s' (%s)", pref, strerror(errno));
+    }
+    return 0;
+}
+
+#endif /* SDL_FILESYSTEM_N3DS */
+
+/* vi: set sts=4 ts=4 sw=4 expandtab: */