[SDL] Add global helper to setup the library.

Call to SDLHelper::Prepare() is needed before first SDL_InitSubSystem().
- Sets hints (SDL configuration vars).
- Configures logging.

src/xenia/helper/sdl/sdl_helper.cc

@@ -0,0 +1,81 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2020 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include "xenia/helper/sdl/sdl_helper.h"
+
+#include "xenia/base/assert.h"
+#include "xenia/base/logging.h"
+
+namespace xe {
+namespace helper {
+namespace sdl {
+bool SDLHelper::is_prepared_ = false;
+
+bool SDLHelper::Prepare() {
+  if (is_prepared_) {
+    return true;
+  }
+  is_prepared_ = true;
+
+  is_prepared_ &= SetHints();
+  is_prepared_ &= RedirectLog();
+
+  return is_prepared_;
+}
+
+bool SDLHelper::SetHints() {
+  bool suc = true;
+
+  // SDL calls timeBeginPeriod(1) but xenia sets this to a lower value before
+  // using NtSetTimerResolution(). Having that value overwritten causes overall
+  // fps drops. Use override priority as timer resolution should always be
+  // managed by xenia. https://bugzilla.libsdl.org/show_bug.cgi?id=5104
+  suc &= SDL_SetHintWithPriority(SDL_HINT_TIMER_RESOLUTION, "0",
+                                 SDL_HINT_OVERRIDE) == SDL_TRUE;
+
+  return suc;
+}
+
+bool SDLHelper::RedirectLog() {
+  // Redirect SDL_Log* output (internal library stuff) to our log system.
+  SDL_LogSetOutputFunction(
+      [](void* userdata, int category, SDL_LogPriority priority,
+         const char* message) {
+        const char* msg_fmt = "SDL: {}";
+        switch (priority) {
+          case SDL_LOG_PRIORITY_VERBOSE:
+          case SDL_LOG_PRIORITY_DEBUG:
+            XELOGD(msg_fmt, message);
+            break;
+          case SDL_LOG_PRIORITY_INFO:
+            XELOGI(msg_fmt, message);
+            break;
+          case SDL_LOG_PRIORITY_WARN:
+            XELOGW(msg_fmt, message);
+            break;
+          case SDL_LOG_PRIORITY_ERROR:
+          case SDL_LOG_PRIORITY_CRITICAL:
+            XELOGE(msg_fmt, message);
+            break;
+          default:
+            XELOGI(msg_fmt, message);
+            assert_always("SDL: Unknown log priority");
+            break;
+        }
+      },
+      nullptr);
+  // SDL itself isn't that talkative. Additionally to this settings there are
+  // hints that can be switched on to output additional internal logging
+  // information.
+  SDL_LogSetAllPriority(SDL_LogPriority::SDL_LOG_PRIORITY_VERBOSE);
+  return true;
+}
+}  // namespace sdl
+}  // namespace helper
+}  // namespace xe