feat: port DDDisplay::GetDimensions to Rust, hook via vtable_replace

First DDDisplay vtable method ported to Rust. Reads display_width/height
from DisplayBase and writes to output pointers. Hooked via vtable_replace
on slot 1 of the DDDisplay vtable (0x66A218).

FlushRender (slot 26) attempted but reverted — DDDisplayWrapper methods
use a non-standard fastcall convention (EDX = result pointer) that the
thiscall bind wrappers can't handle. Documented for future work.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/openwa-core/src/display/dd_display.rs

@@ -270,3 +270,33 @@ pub struct DDDisplayVtable {
 
 // Generate calling wrappers: DDDisplay::set_layer_color(), etc.
 bind_DDDisplayVtable!(DDDisplay, vtable);
+
+// =========================================================================
+// Ported DDDisplay vtable methods
+// =========================================================================
+
+use super::gfx::DisplayGfx;
+
+/// Port of DDDisplay::GetDimensions (vtable slot 1, 0x56A460).
+///
+/// Reads display_width/display_height from DisplayBase and writes them
+/// to the output pointers.
+///
+/// # Safety
+/// `this` must be a valid `*mut DDDisplay` (actually a `*mut DisplayGfx`).
+pub unsafe extern "thiscall" fn get_dimensions(
+    this: *mut DDDisplay,
+    out_w: *mut u32,
+    out_h: *mut u32,
+) {
+    let gfx = this as *mut DisplayGfx;
+    *out_w = (*gfx).base.display_width;
+    *out_h = (*gfx).base.display_height;
+}
+
+// FlushRender (vtable slot 26, 0x56A580) — NOT YET PORTED.
+//
+// Calls DDDisplayWrapper::unlock_surface_write and ::get_renderer_surface,
+// which use a non-standard fastcall convention (EDX = result pointer, not
+// standard thiscall). Needs a naked asm bridge or corrected vtable typing
+// for the DDDisplayWrapper methods before this can be ported.

crates/openwa-dll/src/replacements/display.rs

@@ -7,9 +7,11 @@
 
 use crate::log_line;
 use openwa_core::address::va;
+use openwa_core::display::dd_display::{self, DDDisplayVtable};
 use openwa_core::display::{DisplayBase, SpriteBufferCtrl, SpriteCacheWrapper};
 use openwa_core::rebase::rb;
 use openwa_core::vtable::patch_vtable;
+use openwa_core::vtable_replace;
 use openwa_core::wa_alloc::wa_free;
 
 /// The _purecall function address (calls abort).
@@ -76,6 +78,12 @@ pub fn install() -> Result<(), String> {
             *vt = headless_destructor as *const () as u32;
             let _ = log_line("[Display]   Headless: patched slot 0 (destructor) → Rust");
         })?;
+
+        // Patch DDDisplay vtable (0x66A218): replace ported methods with Rust.
+        vtable_replace!(DDDisplayVtable, va::DD_DISPLAY_VTABLE, {
+            get_dimensions => dd_display::get_dimensions,
+        })?;
+        let _ = log_line("[Display]   DDDisplay: patched get_dimensions → Rust");
     }
 
     Ok(())