v0.3.1 (#3)

- Fix old box contents carrying over when starting a new game by means other than the New Game option (i.e. Once Again, Restart, Wesker Mode)
- Fix selection sound not playing when scrolling to the next row in the box
- Fix an issue where scrolling up in the right column of the box could result in half of a two-slot item being selected
- Moving the selection left from the first slot or right from the last slot will now scroll to the previous/next row of the box, consistent with the base game's behavior

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "re0box"
-version = "0.3.0"
+version = "0.3.1"
 authors = ["descawed <[email protected]>"]
 edition = "2021"
 description = "An item box mod for Resident Evil 0"

src/game.rs

@@ -16,11 +16,14 @@ use super::inventory::{Bag, Item};
 pub const GET_CHARACTER_BAG: usize = 0x0050DA80;
 pub const GET_PARTNER_BAG: usize = 0x004DC8B0;
 pub const DRAW_BAGS: usize = 0x005E6ED0;
+pub const PLAY_SOUND: usize = 0x005EE920;
 pub const GET_PARTNER_BAG_ORG: usize = 0x004DC625;
 pub const ORGANIZE_END1: usize = 0x004DADC7;
 pub const ORGANIZE_END2: usize = 0x004DADDA;
 pub const SCROLL_UP_CHECK: usize = 0x005E386A;
 pub const SCROLL_DOWN_CHECK: usize = 0x005E3935;
+pub const SCROLL_LEFT_CHECK: usize = 0x005E39F1;
+pub const SCROLL_RIGHT_CHECK: usize = 0x005E3AFD;
 pub const GET_PARTNER_CHARACTER: usize = 0x0066DEC0;
 pub const SUB_522A20: usize = 0x00522A20;
 pub const PTR_DCDF3C: usize = 0x00DCDF3C;
@@ -50,7 +53,8 @@ pub const MSG_LOAD1: usize = 0x0040864E;
 pub const MSG_LOAD2: usize = 0x005D6471;
 pub const MSG_LOAD3: usize = 0x005D67E1;
 pub const SHAFT_CHECK: usize = 0x005E3D73;
-pub const NEW_GAME: usize = 0x00405870;
+pub const NEW_GAME: usize = 0x0041249C;
+pub const MOVE_SELECTION_SOUND: i32 = 2050;
 pub const FAIL_SOUND: i32 = 2053;
 pub const NUM_SAVE_SLOTS: usize = 20;
 pub const MAGIC: &[u8] = b"IBOX";
@@ -85,6 +89,7 @@ pub struct Game {
     sub_522a20: Option<unsafe extern "fastcall" fn(*const c_void) -> i32>,
     prepare_inventory: Option<unsafe extern "fastcall" fn(*const c_void) -> bool>,
     sub_4db330: Option<unsafe extern "fastcall" fn(*const c_void) -> i32>,
+    play_sound: Option<unsafe extern "C" fn(i32) -> i32>,
     get_remote_storage: *const unsafe extern "C" fn() -> *const *const usize,
     ptr_dcdf3c: *const *const c_void,
     ptr_dd0bd0: *const *const c_void,
@@ -105,6 +110,7 @@ impl Game {
             sub_522a20: None,
             prepare_inventory: None,
             sub_4db330: None,
+            play_sound: None,
             get_remote_storage: std::ptr::null(),
             ptr_dd0bd0: std::ptr::null(),
             ptr_dcdf3c: std::ptr::null(),
@@ -141,6 +147,7 @@ impl Game {
         self.sub_522a20 = Some(std::mem::transmute(SUB_522A20));
         self.prepare_inventory = Some(std::mem::transmute(PREPARE_INVENTORY));
         self.sub_4db330 = Some(std::mem::transmute(SUB_4DB330));
+        self.play_sound = Some(std::mem::transmute(PLAY_SOUND));
         self.get_remote_storage =
             STEAM_REMOTE_STORAGE as *const unsafe extern "C" fn() -> *const *const usize;
         self.ptr_dd0bd0 = PTR_DD0BD0 as *const *const c_void;
@@ -190,6 +197,10 @@ impl Game {
         self.sub_4db330.unwrap()(unknown)
     }
 
+    pub unsafe fn play_sound(&self, sound_id: i32) -> i32 {
+        self.play_sound.unwrap()(sound_id)
+    }
+
     pub unsafe fn get_remote_storage(&self) -> *const *const usize {
         (*self.get_remote_storage)()
     }

src/inventory.rs

@@ -71,6 +71,10 @@ impl Bag {
                 .map(|i| i.id == SLOT_TWO)
                 .unwrap_or(false)
     }
+
+    pub fn is_slot_two(&self, index: usize) -> bool {
+        self.items[index].id == SLOT_TWO
+    }
 }
 
 #[derive(Debug)]
@@ -192,7 +196,7 @@ impl ItemBox {
         self.is_open = false;
     }
 
-    pub fn scroll_view(&mut self, offset: isize) {
+    pub fn scroll_view(&mut self, offset: isize) -> bool {
         // index must be a multiple of 2; round offset up if it was odd
         let mut new_index = self.index as isize + (offset + 1) & !1;
         if new_index < 0 {
@@ -206,8 +210,14 @@ impl ItemBox {
             }
         }
 
-        self.index = new_index as usize;
-        self.update_view();
+        let new_index = new_index as usize;
+        if self.index != new_index {
+            self.index = new_index;
+            self.update_view();
+            true
+        } else {
+            false
+        }
     }
 
     pub fn is_open(&self) -> bool {

src/lib.rs

@@ -55,6 +55,33 @@ static mut SCROLL_DOWN_TRAMPOLINE: [u8; 20] = [
     0xFF, 0xE6, // jmp esi
 ];
 
+static mut SCROLL_LEFT_TRAMPOLINE: [u8; 22] = [
+    0x79, 0x0D, // jns done
+    0x51, // push ecx
+    0x52, // push edx
+    0x57, // push edi
+    0xE8, 0x00, 0x00, 0x00, 0x00, // call <fn>
+    0x83, 0xC4, 0x04, // add esp,4
+    0x5A, // pop edx
+    0x59, // pop ecx
+    0xBA, 0xF9, 0x39, 0x5E, 0x00, // done: mov edx,0x5e39f9
+    0xFF, 0xE2, // jmp edx
+];
+
+static mut SCROLL_RIGHT_TRAMPOLINE: [u8; 25] = [
+    0x83, 0xF8, 0x06, // cmp eax,6
+    0x7C, 0x0D, // jl done
+    0x51, // push ecx
+    0x52, // push edx
+    0x57, // push edi
+    0xE8, 0x00, 0x00, 0x00, 0x00, // call <fn>
+    0x83, 0xC4, 0x04, // add esp,4
+    0x5A, // pop edx
+    0x59, // pop ecx
+    0xBA, 0xF9, 0x39, 0x5E, 0x00, // done: mov edx,0x5e39f9
+    0xFF, 0xE2, // jmp edx
+];
+
 static mut PARTNER_BAG_ORG_TRAMPOLINE: [u8; 26] = [
     0xE8, 0x00, 0x00, 0x00, 0x00, // call <fn>
     0xB9, 0x41, 0xC6, 0x4D, 0x00, // mov ecx,0x4dc641
@@ -246,11 +273,12 @@ static mut SHAFT_CHECK_TRAMPOLINE: [u8; 31] = [
     0xFF, 0xE0, // do_jmp: jmp eax
 ];
 
-static mut NEW_GAME_TRAMPOLINE: [u8; 17] = [
+static mut NEW_GAME_TRAMPOLINE: [u8; 14] = [
+    0x51, // push ecx
     0xE8, 0x00, 0x00, 0x00, 0x00, // call <fn>
-    0xA1, 0x18, 0xE0, 0xDC, 0x00, // mov eax,[0xdce018]
-    0xB9, 0x75, 0x58, 0x40, 0x00, // mov ecx,0x405875
-    0xFF, 0xE1, // jmp ecx
+    0x59, // pop ecx
+    0xB8, 0x40, 0x13, 0x41, 0x00, // mov eax,0x411340
+    0xFF, 0xE0, // jmp eax
 ];
 
 static mut BOX: ItemBox = ItemBox::new();
@@ -375,10 +403,41 @@ unsafe extern "C" fn track_typewriter_message(had_ink_ribbon: bool) {
     GAME.user_had_ink_ribbon = had_ink_ribbon;
 }
 
+unsafe extern "C" fn scroll_left(unknown: *const c_void) -> i32 {
+    if BOX.is_open() && BOX.scroll_view(-2) {
+        GAME.draw_bags(unknown);
+        if BOX.view().is_slot_two(1) {
+            0
+        } else {
+            1
+        }
+    } else {
+        5 // we're already at the top, so wrap around to the last cell in the view
+    }
+}
+
+unsafe extern "C" fn scroll_right(unknown: *const c_void) -> i32 {
+    if BOX.is_open() && BOX.scroll_view(2) {
+        GAME.draw_bags(unknown);
+        4
+    } else {
+        0 // we're already at the bottom, so wrap around to the first cell in the view
+    }
+}
+
 unsafe extern "C" fn scroll(unknown: *const c_void, offset: isize) {
-    BOX.scroll_view(offset);
-    // by default the inventory display doesn't update at this point, so we have to do it ourselves
-    GAME.draw_bags(unknown);
+    if BOX.is_open() && BOX.scroll_view(offset) {
+        // by default the inventory display doesn't update at this point, so we have to do it ourselves
+        GAME.draw_bags(unknown);
+        // if we've ended up on the second slot of a two-slot item, back up one
+        let selection_index = unknown.offset(0x2bc) as *mut usize;
+        if BOX.view().is_slot_two(*selection_index) {
+            *selection_index -= 1;
+        }
+        // the sound doesn't normally play when moving the cursor past the edges of the inventory,
+        // so we have to do that, too
+        GAME.play_sound(MOVE_SELECTION_SOUND);
+    }
 }
 
 unsafe fn update_box() {
@@ -473,6 +532,20 @@ fn main(reason: u32) -> Result<()> {
                 set_trampoline(&mut SCROLL_DOWN_TRAMPOLINE, 4, scroll as usize)?;
                 patch(SCROLL_DOWN_CHECK, &scroll_down_jump)?;
 
+                // when trying to scroll left from the first inventory cell, scroll the box view
+                let scroll_left_jump =
+                    jmp(SCROLL_LEFT_CHECK, SCROLL_LEFT_TRAMPOLINE.as_ptr() as usize);
+                set_trampoline(&mut SCROLL_LEFT_TRAMPOLINE, 5, scroll_left as usize)?;
+                patch(SCROLL_LEFT_CHECK, &scroll_left_jump)?;
+
+                // when trying to scroll right from the last inventory cell, scroll the box view
+                let scroll_right_jump = jmp(
+                    SCROLL_RIGHT_CHECK,
+                    SCROLL_RIGHT_TRAMPOLINE.as_ptr() as usize,
+                );
+                set_trampoline(&mut SCROLL_RIGHT_TRAMPOLINE, 8, scroll_right as usize)?;
+                patch(SCROLL_RIGHT_CHECK, &scroll_right_jump)?;
+
                 // after the view is organized, copy its contents back into the box
                 let organize_jump1 = jmp(ORGANIZE_END1, ORGANIZE_TRAMPOLINE.as_ptr() as usize);
                 let organize_jump2 = jmp(ORGANIZE_END2, ORGANIZE_TRAMPOLINE.as_ptr() as usize);
@@ -581,9 +654,9 @@ fn main(reason: u32) -> Result<()> {
                 patch(SHAFT_CHECK, &shaft_jump)?;
 
                 // reset the box when starting a new game
-                let new_game_jump = jmp(NEW_GAME, NEW_GAME_TRAMPOLINE.as_ptr() as usize);
-                set_trampoline(&mut NEW_GAME_TRAMPOLINE, 0, new_game as usize)?;
-                patch(NEW_GAME, &new_game_jump)?;
+                let new_game_call = call(NEW_GAME, NEW_GAME_TRAMPOLINE.as_ptr() as usize);
+                set_trampoline(&mut NEW_GAME_TRAMPOLINE, 1, new_game as usize)?;
+                patch(NEW_GAME, &new_game_call)?;
             }
 
             // even if the mod is disabled, we still install our load and save handlers to prevent

src/patch.rs

@@ -13,6 +13,11 @@ pub const fn addr_offset(
     to.overflowing_sub(from + inst_size).0.to_le_bytes()
 }
 
+pub fn call(from: usize, to: usize) -> [u8; 5] {
+    let bytes = addr_offset(from, to, 5);
+    [0xE8, bytes[0], bytes[1], bytes[2], bytes[3]]
+}
+
 pub fn jmp(from: usize, to: usize) -> [u8; 5] {
     let bytes = addr_offset(from, to, 5);
     [0xE9, bytes[0], bytes[1], bytes[2], bytes[3]]