Fixed issues related to negative weapon ammo

(ref. alexbatalov/fallout2-ce#443)

Fixed freeze when reloading an overloaded weapon via the interface bar.

sfall/FalloutEngine/VariableOffsets.h

@@ -211,6 +211,7 @@
 #define FO_VAR_main_window                0x5194F0
 #define FO_VAR_main_window_buf            0x5194F4
 #define FO_VAR_map_elevation              0x519578
+#define FO_VAR_map_flags                  0x631D7C
 #define FO_VAR_map_global_vars            0x51956C
 #define FO_VAR_map_name                   0x631D58
 #define FO_VAR_map_number                 0x631D88

sfall/FalloutEngine/Variables_def.h

@@ -136,6 +136,7 @@ VAR_(main_ctd,                   fo::ComputeAttackResult)
 VAR_(main_death_voiceover_done,  DWORD)
 VAR_(main_window,                DWORD)
 VAR_(map_elevation,              DWORD)
+VAR_(map_flags,                  DWORD)
 VAR_(map_global_vars,            long*)  // array
 VAR_(map_number,                 DWORD)
 VAR_(master_db_handle,           fo::PathNode*)

sfall/Game/items.cpp

@@ -246,7 +246,10 @@ static __declspec(naked) void item_w_mp_cost_replacement() {
 
 // Simplified implementation of item_w_curr_ammo_ engine function
 long __fastcall Items::item_w_curr_ammo(fo::GameObject* item) {
-	if (item) return item->item.charges;
+	if (item) {
+		if (item->item.charges < 0) item->item.charges = 0; // fix negative ammo
+		return item->item.charges;
+	}
 	return 0;
 }
 

sfall/Modules/BugFixes.cpp

@@ -4329,6 +4329,10 @@ void BugFixes::init() {
 	HookCall(0x43C9A0, perks_dialog_hook_tag);
 	HookCall(0x43C9E2, perks_dialog_hook_mutate);
 	HookCall(0x4329D1, editor_design_hook); // reset flags on exiting the character screen
+
+	// Fix to prevent the game from hanging when reloading a weapon overloaded with ammo via the interface bar
+	SafeWrite8(0x4787A2, 0x8D); // jz > jge (item_w_try_reload_)
+	SafeWrite8(0x45F5BD, 0x7E); // jz > jle (intface_toggle_item_state_)
 }
 
 }

sfall/Modules/Interface.cpp

@@ -1050,6 +1050,8 @@ static __declspec(naked) void intface_update_ammo_lights_hack() {
 		mov  eax, 70; // 70 - full ammo bar
 		cmp  edx, eax;
 		cmovg edx, eax;
+		cmp  edx, ebx; // ebx = 0 (empty ammo bar)
+		cmovl edx, ebx;
 		mov  eax, ammoBarXPos; // overwritten engine code
 		retn;
 	}