From 96af33c434bb210135d73e40b899bd1ee281c601 Mon Sep 17 00:00:00 2001
From: Logan McNaughton <848146+loganmc10@users.noreply.github.com>
Date: Sat, 23 Aug 2025 08:54:47 +0200
Subject: [PATCH] Split render frame and update screen, move pause loop (#556)

* split render and update screen functions

* move pause loop
---
 build.rs                   |  1 +
 parallel-rdp/interface.cpp |  8 ++++++--
 parallel-rdp/interface.hpp |  1 +
 src/device/vi.rs           | 12 +++++++++---
 src/ui/video.rs            | 28 +++++++++++++++++++---------
 5 files changed, 36 insertions(+), 14 deletions(-)

diff --git a/build.rs b/build.rs
index 599da1b2..78ef6dd3 100644
--- a/build.rs
+++ b/build.rs
@@ -111,6 +111,7 @@ fn main() {
         .allowlist_function("rdp_close")
         .allowlist_function("rdp_set_vi_register")
         .allowlist_function("rdp_update_screen")
+        .allowlist_function("rdp_render_frame")
         .allowlist_function("rdp_process_commands")
         .allowlist_function("rdp_onscreen_message")
         .allowlist_function("rdp_check_callback")
diff --git a/parallel-rdp/interface.cpp b/parallel-rdp/interface.cpp
index a04e12ca..6580b776 100644
--- a/parallel-rdp/interface.cpp
+++ b/parallel-rdp/interface.cpp
@@ -523,13 +523,17 @@ void rdp_set_vi_register(uint32_t reg, uint32_t value)
 	processor->set_vi_register(RDP::VIRegister(reg), value);
 }
 
-void rdp_update_screen()
+void rdp_render_frame()
 {
 	auto &device = wsi->get_device();
 	render_frame(device);
+	rdp_device.vi_counter += 1;
+}
+
+void rdp_update_screen()
+{
 	wsi->end_frame();
 	wsi->begin_frame();
-	rdp_device.vi_counter += 1;
 }
 
 CALL_BACK rdp_check_callback()
diff --git a/parallel-rdp/interface.hpp b/parallel-rdp/interface.hpp
index 4e81ec59..ad9421f1 100644
--- a/parallel-rdp/interface.hpp
+++ b/parallel-rdp/interface.hpp
@@ -42,6 +42,7 @@ extern "C"
 	void rdp_close();
 	void rdp_set_vi_register(uint32_t reg, uint32_t value);
 	void rdp_update_screen();
+	void rdp_render_frame();
 	CALL_BACK rdp_check_callback();
 	uint64_t rdp_process_commands();
 	void rdp_onscreen_message(const char *_message);
diff --git a/src/device/vi.rs b/src/device/vi.rs
index 568f2c8b..e117c34c 100644
--- a/src/device/vi.rs
+++ b/src/device/vi.rs
@@ -134,9 +134,9 @@ pub fn write_regs(device: &mut device::Device, address: u64, value: u32, mask: u
 }
 
 pub fn vertical_interrupt_event(device: &mut device::Device) {
-    ui::video::update_screen();
+    ui::video::render_frame();
 
-    let mut speed_limiter_toggled = ui::video::check_callback(device);
+    let (mut speed_limiter_toggled, paused) = ui::video::check_callback(device);
 
     if device.netplay.is_some() {
         netplay::send_sync_check(device);
@@ -146,11 +146,17 @@ pub fn vertical_interrupt_event(device: &mut device::Device) {
         }
     }
 
-    device.vi.vi_counter += 1;
     if device.vi.vi_counter.is_multiple_of(device.vi.limit_freq) && device.vi.enable_speed_limiter {
         speed_limiter(device, speed_limiter_toggled);
     }
 
+    ui::video::update_screen();
+    device.vi.vi_counter += 1;
+
+    if device.netplay.is_none() && paused {
+        ui::video::pause_loop();
+    }
+
     if device.cheats.enabled {
         cheats::execute_cheats(device, device.cheats.cheats.clone());
     }
diff --git a/src/ui/video.rs b/src/ui/video.rs
index 2998c742..0f316aa7 100644
--- a/src/ui/video.rs
+++ b/src/ui/video.rs
@@ -93,10 +93,13 @@ pub fn close(ui: &ui::Ui) {
 }
 
 pub fn update_screen() {
-    // when the window is closed, running is set to false
     unsafe { rdp_update_screen() }
 }
 
+pub fn render_frame() {
+    unsafe { rdp_render_frame() }
+}
+
 pub fn state_size() -> usize {
     unsafe { rdp_state_size() }
 }
@@ -130,9 +133,21 @@ pub fn load_state(device: &mut device::Device, rdp_state: *const u8) {
     }
 }
 
-pub fn check_callback(device: &mut device::Device) -> bool {
+pub fn pause_loop() {
+    let mut paused = true;
+    let mut frame_advance = false;
+    while paused && !frame_advance {
+        std::thread::sleep(std::time::Duration::from_secs_f64(1.0 / 60.0));
+        unsafe { sdl3_sys::events::SDL_PumpEvents() };
+        let callback = unsafe { rdp_check_callback() };
+        paused = callback.paused;
+        frame_advance = callback.frame_advance;
+    }
+}
+
+pub fn check_callback(device: &mut device::Device) -> (bool, bool) {
     let mut speed_limiter_toggled = false;
-    let mut callback = unsafe { rdp_check_callback() };
+    let callback = unsafe { rdp_check_callback() };
     device.cpu.running = callback.emu_running;
     if device.netplay.is_none() {
         if callback.save_state {
@@ -144,11 +159,6 @@ pub fn check_callback(device: &mut device::Device) -> bool {
             speed_limiter_toggled = true;
             device.vi.enable_speed_limiter = callback.enable_speedlimiter;
         }
-        while callback.paused && !callback.frame_advance {
-            std::thread::sleep(std::time::Duration::from_secs_f64(1.0 / 60.0));
-            unsafe { sdl3_sys::events::SDL_PumpEvents() };
-            callback = unsafe { rdp_check_callback() };
-        }
     }
 
     if device.ui.storage.save_state_slot != callback.save_state_slot {
@@ -169,7 +179,7 @@ pub fn check_callback(device: &mut device::Device) -> bool {
     } else if callback.raise_volume {
         ui::audio::raise_audio_volume(&mut device.ui);
     }
-    speed_limiter_toggled
+    (speed_limiter_toggled, callback.paused)
 }
 
 pub fn set_register(reg: u32, value: u32) {