From cbc973a559848ab20b52fa9498923b9f797c0ba8 Mon Sep 17 00:00:00 2001
From: Logan McNaughton <848146+loganmc10@users.noreply.github.com>
Date: Sun, 31 May 2026 22:25:28 +0200
Subject: [PATCH] idle RDP before load state (#1000)

* idle RDP before load state

* more
---
 build.rs                   |  1 +
 parallel-rdp/interface.cpp | 16 +++++++---------
 parallel-rdp/interface.hpp |  3 ++-
 src/savestates.rs          |  8 +++++++-
 src/ui/video.rs            |  8 ++++++--
 5 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/build.rs b/build.rs
index 89f3ead..201a331 100644
--- a/build.rs
+++ b/build.rs
@@ -204,6 +204,7 @@ fn main() {
         .allowlist_function("rdp_check_callback")
         .allowlist_function("rdp_check_framebuffers")
         .allowlist_function("rdp_state_size")
+        .allowlist_function("rdp_idle")
         .allowlist_function("rdp_save_state")
         .allowlist_function("rdp_load_state")
         .allowlist_function("rdp_set_fps")
diff --git a/parallel-rdp/interface.cpp b/parallel-rdp/interface.cpp
index 00358d4..39c6a7f 100644
--- a/parallel-rdp/interface.cpp
+++ b/parallel-rdp/interface.cpp
@@ -702,19 +702,17 @@ void rdp_check_framebuffers(uint32_t address, uint32_t length) {
 
 size_t rdp_state_size() { return sizeof(RDP_DEVICE); }
 
-void rdp_save_state(uint8_t *state, bool rewind) {
-  if (!rewind) { // speed hack for rewind
-    processor->idle();
-    rdram_dirty.assign(gfx_info.RDRAM_SIZE >> 3, false);
-    sync_signal = 0;
-  }
+void rdp_idle() {
+  processor->idle();
+  rdram_dirty.assign(gfx_info.RDRAM_SIZE >> 3, false);
+  sync_signal = 0;
+}
+
+void rdp_save_state(uint8_t *state) {
   memcpy(state, &rdp_device, sizeof(RDP_DEVICE));
 }
 
 void rdp_load_state(GFX_INFO _gfx_info, const uint8_t *state) {
-  sync_signal = 0;
-  rdram_dirty.assign(gfx_info.RDRAM_SIZE >> 3, false);
-
   gfx_info = _gfx_info;
   memcpy(&rdp_device, state, sizeof(RDP_DEVICE));
 }
diff --git a/parallel-rdp/interface.hpp b/parallel-rdp/interface.hpp
index 2cc2384..310bd7c 100644
--- a/parallel-rdp/interface.hpp
+++ b/parallel-rdp/interface.hpp
@@ -61,7 +61,8 @@ uint64_t rdp_process_commands();
 void rdp_onscreen_message(const char *message, MESSAGE_LENGTH milliseconds);
 void rdp_check_framebuffers(uint32_t address, uint32_t length);
 size_t rdp_state_size();
-void rdp_save_state(uint8_t *state, bool rewind);
+void rdp_idle();
+void rdp_save_state(uint8_t *state);
 void rdp_load_state(GFX_INFO _gfx_info, const uint8_t *state);
 void rdp_set_fps(uint32_t fps, uint32_t vis);
 
diff --git a/src/savestates.rs b/src/savestates.rs
index 4868062..9782f46 100644
--- a/src/savestates.rs
+++ b/src/savestates.rs
@@ -111,8 +111,12 @@ pub fn process_savestates(device: &mut device::Device) {
 }
 
 fn create_savestate(device: &mut device::Device, rewind: bool) {
+    if !rewind {
+        // skipped on rewind as a speed hack
+        ui::video::idle(); // to flush the RDP so the RDRAM is updated
+    }
     let mut rdp_state: Vec<u8> = vec![0; ui::video::state_size()];
-    ui::video::save_state(rdp_state.as_mut_ptr(), rewind);
+    ui::video::save_state(rdp_state.as_mut_ptr());
 
     let mut ra_state: Vec<u8> = vec![0; retroachievements::state_size()];
     retroachievements::save_state(ra_state.as_mut_ptr(), ra_state.len());
@@ -228,6 +232,8 @@ fn load_savestate(device: &mut device::Device, rewind: bool) {
     if let Some(mut state) = state_data
         && device.rdram.size == state.device.rdram.size
     {
+        ui::video::idle(); // to flush the RDP so it doesn't overwrite the RDRAM
+
         device.savestate.last_rewind_saved = state.device.vi.elapsed_time;
 
         std::mem::swap(&mut device.ui.storage.saves, &mut state.saves);
diff --git a/src/ui/video.rs b/src/ui/video.rs
index ac9f212..62d1fb1 100644
--- a/src/ui/video.rs
+++ b/src/ui/video.rs
@@ -161,8 +161,12 @@ pub fn state_size() -> usize {
     unsafe { rdp_state_size() }
 }
 
-pub fn save_state(rdp_state: *mut u8, rewind: bool) {
-    unsafe { rdp_save_state(rdp_state, rewind) }
+pub fn save_state(rdp_state: *mut u8) {
+    unsafe { rdp_save_state(rdp_state) }
+}
+
+pub fn idle() {
+    unsafe { rdp_idle() }
 }
 
 pub fn load_state(device: &mut device::Device, rdp_state: *const u8) {