gitadora: option to disable frame limiter (#848)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
There is a patch for GITADORA series that fixes frame pacing on modern
Windows. Turn it into a signature patch and embed it into the game.

## Testing
should work for all 64-bit gitadora versions, pre-GWD

src/spice2x/games/gitadora/gitadora.cpp

@@ -31,6 +31,7 @@ namespace games::gitadora {
 
     // settings
     bool TWOCHANNEL = false;
+    bool DISABLE_FRAME_LIMITER = false;
     std::optional<unsigned int> CAB_TYPE = std::nullopt;
     bool P1_LEFTY = false;
     bool P2_LEFTY = false;
@@ -65,6 +66,46 @@ namespace games::gitadora {
 
         return CreateDirectoryA(lpPathName, lpSecurityAttributes);
     }
+
+    // libshare-pj paces mainloop with separate 12 ms and 16 ms waits. these waits
+    // interfere with the game's normal display synchronization on modern Windows
+    // and can hold a nominal 60 FPS game near 58 FPS. locate the instruction
+    // sequences at runtime so the fix does not depend on per-version file offsets.
+    static void disable_mainloop_frame_limiter(HMODULE sharepj_module) {
+        if (!sharepj_module) {
+            return;
+        }
+
+        // both limiters have the same shape, only the millisecond target xx differs
+        // (0Ch for the 12 ms limiter, 10h for the 16 ms one):
+        //
+        // 48 83 F8 xx:     cmp rax, xx;   compare elapsed frame time with the target
+        // 73 10:           jae +10h;      skip the wait once the target has elapsed
+        // B9 xx 00 00 00:  mov ecx, xx;   load the target
+        // 48 2B C8:        sub rcx, rax;  calculate the remaining wait time
+        // 74 06:           je +6h;        skip the following six-byte Sleep call if no wait remains
+        //
+        // changing jae (73h) to jmp (EBh) makes each block always take its existing
+        // skip path, which bypasses only the associated Sleep call and leaves the 10h
+        // branch displacement and every other wait untouched.
+        const auto limiter_12ms_disabled = replace_pattern(
+                sharepj_module,
+                "4883F80C7310B90C000000482BC87406",
+                "????????EB??????????????????????", 0, 0);
+        const auto limiter_16ms_disabled = replace_pattern(
+                sharepj_module,
+                "4883F8107310B910000000482BC87406",
+                "????????EB??????????????????????", 0, 0);
+
+        if (!limiter_12ms_disabled || !limiter_16ms_disabled) {
+            log_fatal(
+                "gitadora",
+                "failed to disable libshare-pj mainloop frame limiter (-gdnoframelimiter), ensure patch is not already applied");
+            return;
+        }
+
+        log_info("gitadora", "successfully disabled libshare-pj mainloop frame limiter (-gdnoframelimiter)");
+    }
 #endif
 
     /*
@@ -687,6 +728,12 @@ namespace games::gitadora {
         HMODULE system_module = libutils::try_module("libsystem.dll");
 
         // patches
+#ifdef SPICE64
+        if (DISABLE_FRAME_LIMITER && !is_arena_model()) {
+            disable_mainloop_frame_limiter(sharepj_module);
+        }
+#endif
+
         detour::inline_hook((void *) eam_network_detected_ip_change, libutils::try_proc(
                 sharepj_module, "eam_network_detected_ip_change"));
         detour::inline_hook((void *) eam_network_settings_conflict, libutils::try_proc(

src/spice2x/games/gitadora/gitadora.h

@@ -13,6 +13,7 @@ namespace games::gitadora {
 
     // settings
     extern bool TWOCHANNEL;
+    extern bool DISABLE_FRAME_LIMITER;
     extern std::optional<unsigned int> CAB_TYPE;
     extern bool P1_LEFTY;
     extern bool P2_LEFTY;

src/spice2x/launcher/launcher.cpp

@@ -644,6 +644,9 @@ int main_implementation(int argc, char *argv[]) {
     if (options[launcher::Options::LoadGitaDoraModule].value_bool()) {
         attach_gitadora = true;
     }
+    if (options[launcher::Options::GitaDoraDisableFrameLimiter].value_bool()) {
+        games::gitadora::DISABLE_FRAME_LIMITER = true;
+    }
     if (options[launcher::Options::GitaDoraCabinetType].is_active()) {
         games::gitadora::CAB_TYPE = options[launcher::Options::GitaDoraCabinetType].value_uint32();
     }

src/spice2x/launcher/options.cpp

@@ -1202,6 +1202,19 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .category = "Game Options",
         .quick_setting_category = "Game",
     },
+    {
+        .title = "GitaDora Disable Frame Limiter (EXPERIMENTAL)",
+        .name = "gdnoframelimiter",
+        .desc = "Only for GITADORA to GALAXY WAVE; not for XG series or Arena Model.\n\n"
+            "Game engine's built-in frame limiter can result in unstable frame pacing "
+            "(around 56-58 FPS) on modern Windows. Turning this on disables that and "
+            "forces the game to rely on V-Sync instead, resulting in a stable FPS.\n\n"
+            "Ensure your monitors are set to 60Hz.",
+        .type = OptionType::Bool,
+        .game_name = "GitaDora",
+        .category = "Game Options",
+        .quick_setting_category = "Game",
+    },
     {
         .title = "GitaDora Cabinet Type",
         .name = "gdcabtype",

src/spice2x/launcher/options.h

@@ -114,6 +114,7 @@ namespace launcher {
             LoadHelloPopnMusicModule,
             LoadGitaDoraModule,
             GitaDoraTwoChannelAudio,
+            GitaDoraDisableFrameLimiter,
             GitaDoraCabinetType,
             GitaDoraLefty,
             GitaDoraWailHold,