From 5a079a2d114f96d4847d1ee305d5b7c16eeec50e Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Sat, 27 Dec 2025 12:03:39 -0800
Subject: Initial commit

---
 .../src/main/generic/SDL_sysmain_callbacks.c       | 96 ++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 contrib/SDL-3.2.8/src/main/generic/SDL_sysmain_callbacks.c

(limited to 'contrib/SDL-3.2.8/src/main/generic/SDL_sysmain_callbacks.c')

diff --git a/contrib/SDL-3.2.8/src/main/generic/SDL_sysmain_callbacks.c b/contrib/SDL-3.2.8/src/main/generic/SDL_sysmain_callbacks.c
new file mode 100644
index 0000000..716489f
--- /dev/null
+++ b/contrib/SDL-3.2.8/src/main/generic/SDL_sysmain_callbacks.c
@@ -0,0 +1,96 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 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"
+#include "../SDL_main_callbacks.h"
+#include "../../video/SDL_sysvideo.h"
+
+#ifndef SDL_PLATFORM_IOS
+
+static int callback_rate_increment = 0;
+static bool iterate_after_waitevent = false;
+
+static void SDLCALL MainCallbackRateHintChanged(void *userdata, const char *name, const char *oldValue, const char *newValue)
+{
+    iterate_after_waitevent = newValue && (SDL_strcmp(newValue, "waitevent") == 0);
+    if (iterate_after_waitevent) {
+        callback_rate_increment = 0;
+    } else {
+        const int callback_rate = newValue ? SDL_atoi(newValue) : 0;
+        if (callback_rate > 0) {
+            callback_rate_increment = ((Uint64) 1000000000) / ((Uint64) callback_rate);
+        } else {
+            callback_rate_increment = 0;
+        }
+    }
+}
+
+static SDL_AppResult GenericIterateMainCallbacks(void)
+{
+    if (iterate_after_waitevent) {
+        SDL_WaitEvent(NULL);
+    }
+    return SDL_IterateMainCallbacks(!iterate_after_waitevent);
+}
+
+int SDL_EnterAppMainCallbacks(int argc, char* argv[], SDL_AppInit_func appinit, SDL_AppIterate_func appiter, SDL_AppEvent_func appevent, SDL_AppQuit_func appquit)
+{
+    SDL_AppResult rc = SDL_InitMainCallbacks(argc, argv, appinit, appiter, appevent, appquit);
+    if (rc == 0) {
+        SDL_AddHintCallback(SDL_HINT_MAIN_CALLBACK_RATE, MainCallbackRateHintChanged, NULL);
+
+        Uint64 next_iteration = callback_rate_increment ? (SDL_GetTicksNS() + callback_rate_increment) : 0;
+
+        while ((rc = GenericIterateMainCallbacks()) == SDL_APP_CONTINUE) {
+            // !!! FIXME: this can be made more complicated if we decide to
+            // !!! FIXME: optionally hand off callback responsibility to the
+            // !!! FIXME: video subsystem (for example, if Wayland has a
+            // !!! FIXME: protocol to drive an animation loop, maybe we hand
+            // !!! FIXME: off to them here if/when the video subsystem becomes
+            // !!! FIXME: initialized).
+
+            // Try to run at whatever rate the hint requested. This makes this
+            //  not eat all the CPU in simple things like loopwave. By
+            //  default, we run as fast as possible, which means we'll clamp to
+            //  vsync in common cases, and won't be restrained to vsync if the
+            //  app is doing a benchmark or doesn't want to be, based on how
+            // they've set up that window.
+            if (callback_rate_increment == 0) {
+                next_iteration = 0; // just clear the timer and run at the pace the video subsystem allows.
+            } else {
+                const Uint64 now = SDL_GetTicksNS();
+                if (next_iteration > now) {  // Running faster than the limit, sleep a little.
+                    SDL_DelayPrecise(next_iteration - now);
+                } else {
+                    next_iteration = now;  // if running behind, reset the timer. If right on time, `next_iteration` already equals `now`.
+                }
+                next_iteration += callback_rate_increment;
+            }
+        }
+
+        SDL_RemoveHintCallback(SDL_HINT_MAIN_CALLBACK_RATE, MainCallbackRateHintChanged, NULL);
+    }
+    SDL_QuitMainCallbacks(rc);
+
+    return (rc == SDL_APP_FAILURE) ? 1 : 0;
+}
+
+#endif // !SDL_PLATFORM_IOS
-- 
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