4 files changed, 64 insertions, 9 deletions

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 66de33799..949748178 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -41,6 +41,7 @@ add_library(core STATIC
     file_sys/bis_factory.h
     file_sys/card_image.cpp
     file_sys/card_image.h
+    file_sys/common_funcs.h
     file_sys/content_archive.cpp
     file_sys/content_archive.h
     file_sys/control_metadata.cpp
diff --git a/src/core/file_sys/common_funcs.h b/src/core/file_sys/common_funcs.h
new file mode 100644
index 000000000..7ed97aa50
--- /dev/null
+++ b/src/core/file_sys/common_funcs.h
@@ -0,0 +1,56 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+
+namespace FileSys {
+
+constexpr u64 AOC_TITLE_ID_MASK = 0x7FF;
+constexpr u64 AOC_TITLE_ID_OFFSET = 0x1000;
+constexpr u64 BASE_TITLE_ID_MASK = 0xFFFFFFFFFFFFE000;
+
+/**
+ * Gets the base title ID from a given title ID.
+ *
+ * @param title_id The title ID.
+ * @returns The base title ID.
+ */
+[[nodiscard]] constexpr u64 GetBaseTitleID(u64 title_id) {
+    return title_id & BASE_TITLE_ID_MASK;
+}
+
+/**
+ * Gets the base title ID with a program index offset from a given title ID.
+ *
+ * @param title_id The title ID.
+ * @param program_index The program index.
+ * @returns The base title ID with a program index offset.
+ */
+[[nodiscard]] constexpr u64 GetBaseTitleIDWithProgramIndex(u64 title_id, u64 program_index) {
+    return GetBaseTitleID(title_id) + program_index;
+}
+
+/**
+ * Gets the AOC (Add-On Content) base title ID from a given title ID.
+ *
+ * @param title_id The title ID.
+ * @returns The AOC base title ID.
+ */
+[[nodiscard]] constexpr u64 GetAOCBaseTitleID(u64 title_id) {
+    return GetBaseTitleID(title_id) + AOC_TITLE_ID_OFFSET;
+}
+
+/**
+ * Gets the AOC (Add-On Content) ID from a given AOC title ID.
+ *
+ * @param aoc_title_id The AOC title ID.
+ * @returns The AOC ID.
+ */
+[[nodiscard]] constexpr u64 GetAOCID(u64 aoc_title_id) {
+    return aoc_title_id & AOC_TITLE_ID_MASK;
+}
+
+} // namespace FileSys
diff --git a/src/core/file_sys/patch_manager.cpp b/src/core/file_sys/patch_manager.cpp
index e9d1607d0..7c3284df8 100644
--- a/src/core/file_sys/patch_manager.cpp
+++ b/src/core/file_sys/patch_manager.cpp
@@ -12,6 +12,7 @@
 #include "common/logging/log.h"
 #include "common/string_util.h"
 #include "core/core.h"
+#include "core/file_sys/common_funcs.h"
 #include "core/file_sys/content_archive.h"
 #include "core/file_sys/control_metadata.h"
 #include "core/file_sys/ips_layer.h"
@@ -30,7 +31,6 @@ namespace FileSys {
 namespace {
 
 constexpr u32 SINGLE_BYTE_MODULUS = 0x100;
-constexpr u64 DLC_BASE_TITLE_ID_MASK = 0xFFFFFFFFFFFFE000;
 
 constexpr std::array<const char*, 14> EXEFS_FILE_NAMES{
     "main",    "main.npdm", "rtld",    "sdk",     "subsdk0", "subsdk1", "subsdk2",
@@ -532,7 +532,7 @@ PatchManager::PatchVersionNames PatchManager::GetPatchVersionNames(VirtualFile u
     dlc_match.reserve(dlc_entries.size());
     std::copy_if(dlc_entries.begin(), dlc_entries.end(), std::back_inserter(dlc_match),
                  [this](const ContentProviderEntry& entry) {
-                     return (entry.title_id & DLC_BASE_TITLE_ID_MASK) == title_id &&
+                     return GetBaseTitleID(entry.title_id) == title_id &&
                             content_provider.GetEntry(entry)->GetStatus() ==
                                 Loader::ResultStatus::Success;
                  });
diff --git a/src/core/hle/service/aoc/aoc_u.cpp b/src/core/hle/service/aoc/aoc_u.cpp
index 6abac3f78..17ba21496 100644
--- a/src/core/hle/service/aoc/aoc_u.cpp
+++ b/src/core/hle/service/aoc/aoc_u.cpp
@@ -7,6 +7,7 @@
 #include <vector>
 #include "common/logging/log.h"
 #include "core/core.h"
+#include "core/file_sys/common_funcs.h"
 #include "core/file_sys/content_archive.h"
 #include "core/file_sys/control_metadata.h"
 #include "core/file_sys/nca_metadata.h"
@@ -23,11 +24,8 @@
 
 namespace Service::AOC {
 
-constexpr u64 DLC_BASE_TITLE_ID_MASK = 0xFFFFFFFFFFFFE000;
-constexpr u64 DLC_BASE_TO_AOC_ID = 0x1000;
-
 static bool CheckAOCTitleIDMatchesBase(u64 title_id, u64 base) {
-    return (title_id & DLC_BASE_TITLE_ID_MASK) == base;
+    return FileSys::GetBaseTitleID(title_id) == base;
 }
 
 static std::vector<u64> AccumulateAOCTitleIDs(Core::System& system) {
@@ -123,11 +121,11 @@ void AOC_U::ListAddOnContent(Kernel::HLERequestContext& ctx) {
     const auto& disabled = Settings::values.disabled_addons[current];
     if (std::find(disabled.begin(), disabled.end(), "DLC") == disabled.end()) {
         for (u64 content_id : add_on_content) {
-            if ((content_id & DLC_BASE_TITLE_ID_MASK) != current) {
+            if (FileSys::GetBaseTitleID(content_id) != current) {
                 continue;
             }
 
-            out.push_back(static_cast<u32>(content_id & 0x7FF));
+            out.push_back(static_cast<u32>(FileSys::GetAOCID(content_id)));
         }
     }
 
@@ -169,7 +167,7 @@ void AOC_U::GetAddOnContentBaseId(Kernel::HLERequestContext& ctx) {
 
     const auto res = pm.GetControlMetadata();
     if (res.first == nullptr) {
-        rb.Push(title_id + DLC_BASE_TO_AOC_ID);
+        rb.Push(FileSys::GetAOCBaseTitleID(title_id));
         return;
     }