Add fix_invulnerable_ship_artillery_slots mod

Author: Trolldemorted

.github/workflows/release.yml

@@ -15,6 +15,7 @@ jobs:
     - run: |
         mkdir mods
         mv target/i686-pc-windows-msvc/release/fix_damage_to_offside_ship_artillery.dll ./mods/
+        mv target/i686-pc-windows-msvc/release/fix_invulnerable_ship_artillery_slots.dll ./mods/
         mv target/i686-pc-windows-msvc/release/fix_market_hall_production_town.dll ./mods/
         mv target/i686-pc-windows-msvc/release/fix_new_settlement_ware_production.dll ./mods/
         mv target/i686-pc-windows-msvc/release/fix_siege_beggar_satisfaction_bonus.dll ./mods/

Cargo.toml

@@ -5,6 +5,7 @@ members = [
     "aimcli",
     "cprcli",
     "mod-fix-damage-to-offside-ship-artillery",
+    "mod-fix-invulnerable-ship-artillery-slots",
     "mod-fix-market-hall-production-town",
     "mod-fix-new-settlement-ware-production",
     "mod-fix-siege-beggar-satisfaction-bonus", 

mod-fix-invulnerable-ship-artillery-slots/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "mod-fix-invulnerable-ship-artillery-slots"
+edition = "2021"
+version.workspace = true
+
+[lib]
+crate-type = ["cdylib"]
+name="fix_invulnerable_ship_artillery_slots"
+
+[dependencies]
+p3-api = { path = "../p3-api" }
+log = { workspace = true }
+win_dbg_logger = { workspace = true }
+hooklet = { workspace = true }

mod-fix-invulnerable-ship-artillery-slots/src/ffi.rs

@@ -0,0 +1,90 @@
+use std::{arch::global_asm, ffi::c_void};
+
+use hooklet::X86Rel32Type;
+use log::{debug, LevelFilter};
+
+const PATCH_ADDRESS_1: u32 = 0x0061FDDB;
+const PATCH_ADDRESS_2: u32 = 0x0061FE8E;
+
+static CONTINUATION_1: u32 = 0x0061FDE2;
+static CONTINUATION_2: u32 = 0x0061FE96;
+
+#[no_mangle]
+pub unsafe extern "C" fn start() -> u32 {
+    let _ = log::set_logger(&win_dbg_logger::DEBUGGER_LOGGER);
+    log::set_max_level(LevelFilter::Trace);
+
+    if hooklet::deploy_rel32_raw(PATCH_ADDRESS_1 as _, (&fix_index_calc1) as *const _ as _, X86Rel32Type::Jump).is_err() {
+        return 1;
+    }
+
+    if hooklet::deploy_rel32_raw(PATCH_ADDRESS_2 as _, (&fix_index_calc2) as *const _ as _, X86Rel32Type::Jump).is_err() {
+        return 2;
+    }
+
+    0
+}
+
+#[no_mangle]
+pub unsafe extern "cdecl" fn get_correct_index(index: u32) -> u32 {
+    let multiplied_index = index * 2;
+    let correct_index = match multiplied_index {
+        4 => 0,
+        _ => 2,
+    };
+    debug!("Correcting artillery slot index from {multiplied_index} to {correct_index}");
+
+    correct_index
+}
+
+extern "C" {
+    static fix_index_calc1: c_void;
+    static fix_index_calc2: c_void;
+}
+
+global_asm!(
+    "
+.global {fix_index_calc1}
+{fix_index_calc1}:
+# save regs
+push ecx
+push edx
+
+push eax
+call {get_correct_index}
+pop edx
+
+# restore regs
+pop edx
+pop ecx
+
+jmp [{continuation}]
+",
+fix_index_calc1 = sym fix_index_calc1,
+get_correct_index = sym get_correct_index,
+continuation = sym CONTINUATION_1
+);
+
+global_asm!(
+    "
+.global {fix_index_calc2}
+{fix_index_calc2}:
+# save regs
+push eax
+push edx
+
+push ecx
+call {get_correct_index}
+mov ecx, eax
+pop edx
+
+# restore regs
+pop edx
+pop eax
+
+jmp [{continuation}]
+",
+fix_index_calc2 = sym fix_index_calc2,
+get_correct_index = sym get_correct_index,
+continuation = sym CONTINUATION_2
+);

mod-fix-invulnerable-ship-artillery-slots/src/lib.rs

@@ -0,0 +1 @@
+pub(crate) mod ffi;