refactor: eliminate pointer arithmetic from FireWeapon impl

- Rename WeaponEntry.fire_complete → fire_params_start (u32), since
its address is passed to sub-functions as a params base pointer
- Add CTaskWorm::fire_complete() / set_fire_complete() for the
completion flag at CGameTask.subclass_data[12] (worm+0x3C)
- Rename params → fire_params, worm_u32 → w for clarity
- All field reads now go through typed struct access, no raw offsets

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

crates/openwa-core/src/game/weapon.rs

@@ -135,9 +135,9 @@ pub struct WeaponEntry {
     pub fire_subtype_34: i32,
     /// +0x38: Fire subtype for weapon types 1 (projectile) and 2 (rope).
     pub fire_subtype_38: i32,
-    /// +0x3C: Fire completion flag / params base.
-    /// Set to 0 before dispatch, 1 after. Address also passed to fire handlers.
-    pub fire_complete: i32,
+    /// +0x3C: Weapon fire params start. Address of this field is passed
+    /// to fire sub-functions as the params base pointer.
+    pub fire_params_start: u32,
     /// +0x40-0x1CF: Unknown fields.
     pub _unknown_40: [u8; 0x1D0 - 0x40],
 }

crates/openwa-core/src/task/worm.rs

@@ -186,9 +186,20 @@ impl CTaskWorm {
         unsafe { *((self as *const CTaskWorm as *const u8).add(0x44) as *const u32) }
     }
 
-    // Weapon fire state lives in the WeaponEntry pointed to by active_weapon_entry
-    // (+0x36C), NOT in CTaskWorm itself. See WeaponEntry fields: fire_type (+0x30),
-    // fire_subtype_34 (+0x34), fire_subtype_38 (+0x38), fire_complete (+0x3C).
+    // Weapon fire dispatch state:
+    // - Fire type/subtypes live in the WeaponEntry (via active_weapon_entry at +0x36C)
+    // - Completion flag lives in CGameTask.subclass_data[12] (this object, at +0x3C)
+
+    /// Weapon fire completion flag at CGameTask+0x3C (subclass_data[12]).
+    /// Set to 0 before FireWeapon dispatch, 1 after.
+    pub fn fire_complete(&self) -> i32 {
+        i32::from_ne_bytes(self.base.subclass_data[12..16].try_into().unwrap())
+    }
+
+    /// Set the weapon fire completion flag.
+    pub fn set_fire_complete(&mut self, value: i32) {
+        self.base.subclass_data[12..16].copy_from_slice(&value.to_ne_bytes());
+    }
 
     /// Returns a reference to the vtable.
     ///

crates/openwa-wormkit/src/replacements/weapon.rs

@@ -196,48 +196,47 @@ unsafe extern "cdecl" fn fire_weapon_impl(
     let weapon_type = (*entry).fire_type;
     let subtype_34 = (*entry).fire_subtype_34;
     let subtype_38 = (*entry).fire_subtype_38;
-    let params = &raw const (*entry).fire_complete as u32;
-    let worm_u32 = worm as u32;
+    let fire_params = &raw const (*entry).fire_params_start as u32;
+    let w = worm as u32;
 
     // Log weapon fire
     let weapon_id = (*worm).selected_weapon;
     let weapon_name = Weapon::try_from(weapon_id)
-        .map(|w| format!("{:?}", w))
+        .map(|wp| format!("{:?}", wp))
         .unwrap_or_else(|id| format!("Unknown({})", id));
     let _ = log_line(&format!(
         "[Weapon] FireWeapon: {} (id={}) type={} sub34={} sub38={}",
         weapon_name, weapon_id, weapon_type, subtype_34, subtype_38
     ));
 
-    // Completion flag at CGameTask.subclass_data[12] (worm+0x3C), NOT WeaponEntry
-    *(worm as *mut u8).add(0x3C).cast::<i32>() = 0;
+    (*worm).set_fire_complete(0);
 
     match weapon_type {
         1 => match subtype_38 {
-            1 => call_fire_stdcall1(worm_u32, params, rb(0x51EC80)),                    // PlacedExplosive
-            2 => call_fire_stdcall3(worm_u32, params, local_struct, rb(0x51DFB0)),      // Projectile
-            3 => call_fire_thiscall2(worm_u32, params, local_struct, rb(0x51E0F0)),     // CreateWeaponProjectile
-            4 => call_fire_stdcall2(worm_u32, params, local_struct, rb(0x51ED90)),      // Shotgun
+            1 => call_fire_stdcall1(w, fire_params, rb(0x51EC80)),                    // PlacedExplosive
+            2 => call_fire_stdcall3(w, fire_params, local_struct, rb(0x51DFB0)),      // Projectile
+            3 => call_fire_thiscall2(w, fire_params, local_struct, rb(0x51E0F0)),     // CreateWeaponProjectile
+            4 => call_fire_stdcall2(w, fire_params, local_struct, rb(0x51ED90)),      // Shotgun
             _ => {}
         },
         2 => match subtype_38 {
-            1 => call_fire_stdcall3(worm_u32, params, local_struct, rb(0x51E1C0)),      // RopeType1
-            2 => call_fire_thiscall2(worm_u32, params, local_struct, rb(0x51E0F0)),     // CreateWeaponProjectile
-            3 => call_fire_stdcall3(worm_u32, params, local_struct, rb(0x51E240)),      // RopeType3
+            1 => call_fire_stdcall3(w, fire_params, local_struct, rb(0x51E1C0)),      // RopeType1
+            2 => call_fire_thiscall2(w, fire_params, local_struct, rb(0x51E0F0)),     // CreateWeaponProjectile
+            3 => call_fire_stdcall3(w, fire_params, local_struct, rb(0x51E240)),      // RopeType3
             _ => {}
         },
         3 => {
-            let params_34 = &raw const (*entry).fire_subtype_34 as u32;
-            call_fire_stdcall3(worm_u32, params_34, local_struct, rb(0x51E2C0));        // GrenadeMortar
+            let subtype_34_ptr = &raw const (*entry).fire_subtype_34 as u32;
+            call_fire_stdcall3(w, subtype_34_ptr, local_struct, rb(0x51E2C0));        // GrenadeMortar
         }
         4 => {
-            let params_38 = &raw const (*entry).fire_subtype_38 as u32;
-            fire_weapon_special(subtype_34, params_38, worm_u32, local_struct);
+            let subtype_38_ptr = &raw const (*entry).fire_subtype_38 as u32;
+            fire_weapon_special(subtype_34, subtype_38_ptr, w, local_struct);
         }
         _ => {}
     }
 
-    *(worm as *mut u8).add(0x3C).cast::<i32>() = 1;
+    (*worm).set_fire_complete(1);
 }
 
 // ── Sub-function bridges ────────────────────────────────────