cheat_engine: Add parser and interpreter for game cheats

3 files changed, 715 insertions, 0 deletions

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 988356c65..199a0c2e3 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -31,6 +31,8 @@ add_library(core STATIC
     file_sys/bis_factory.h
     file_sys/card_image.cpp
     file_sys/card_image.h
+    file_sys/cheat_engine.cpp
+    file_sys/cheat_engine.h
     file_sys/content_archive.cpp
     file_sys/content_archive.h
     file_sys/control_metadata.cpp
diff --git a/src/core/file_sys/cheat_engine.cpp b/src/core/file_sys/cheat_engine.cpp
new file mode 100644
index 000000000..e4383d8c1
--- /dev/null
+++ b/src/core/file_sys/cheat_engine.cpp
@@ -0,0 +1,487 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <locale>
+#include "common/hex_util.h"
+#include "common/microprofile.h"
+#include "common/swap.h"
+#include "core/core.h"
+#include "core/core_timing.h"
+#include "core/core_timing_util.h"
+#include "core/file_sys/cheat_engine.h"
+#include "core/hle/kernel/process.h"
+#include "core/hle/service/hid/controllers/controller_base.h"
+#include "core/hle/service/hid/controllers/npad.h"
+#include "core/hle/service/hid/hid.h"
+#include "core/hle/service/sm/sm.h"
+
+namespace FileSys {
+
+constexpr u64 CHEAT_ENGINE_TICKS = CoreTiming::BASE_CLOCK_RATE / 60;
+constexpr u32 KEYPAD_BITMASK = 0x3FFFFFF;
+
+u64 Cheat::Address() const {
+    u64 out;
+    std::memcpy(&out, raw.data(), sizeof(u64));
+    return Common::swap64(out) & 0xFFFFFFFFFF;
+}
+
+u64 Cheat::ValueWidth(u64 offset) const {
+    return Value(offset, width);
+}
+
+u64 Cheat::Value(u64 offset, u64 width) const {
+    u64 out;
+    std::memcpy(&out, raw.data() + offset, sizeof(u64));
+    out = Common::swap64(out);
+    if (width == 8)
+        return out;
+    return out & ((1ull << (width * CHAR_BIT)) - 1);
+}
+
+u32 Cheat::KeypadValue() const {
+    u32 out;
+    std::memcpy(&out, raw.data(), sizeof(u32));
+    return Common::swap32(out) & 0x0FFFFFFF;
+}
+
+void CheatList::SetMemoryParameters(VAddr main_begin, VAddr heap_begin, VAddr main_end,
+                                    VAddr heap_end, MemoryWriter writer, MemoryReader reader) {
+    this->main_region_begin = main_begin;
+    this->main_region_end = main_end;
+    this->heap_region_begin = heap_begin;
+    this->heap_region_end = heap_end;
+    this->writer = writer;
+    this->reader = reader;
+}
+
+MICROPROFILE_DEFINE(Cheat_Engine, "Add-Ons", "Cheat Engine", MP_RGB(70, 200, 70));
+
+void CheatList::Execute() {
+    MICROPROFILE_SCOPE(Cheat_Engine);
+
+    std::fill(scratch.begin(), scratch.end(), 0);
+    in_standard = false;
+    for (std::size_t i = 0; i < master_list.size(); ++i) {
+        LOG_DEBUG(Common_Filesystem, "Executing block #{:08X} ({})", i, master_list[i].first);
+        current_block = i;
+        ExecuteBlock(master_list[i].second);
+    }
+
+    in_standard = true;
+    for (std::size_t i = 0; i < standard_list.size(); ++i) {
+        LOG_DEBUG(Common_Filesystem, "Executing block #{:08X} ({})", i, standard_list[i].first);
+        current_block = i;
+        ExecuteBlock(standard_list[i].second);
+    }
+}
+
+CheatList::CheatList(ProgramSegment master, ProgramSegment standard)
+    : master_list(master), standard_list(standard) {}
+
+bool CheatList::EvaluateConditional(const Cheat& cheat) const {
+    using ComparisonFunction = bool (*)(u64, u64);
+    constexpr ComparisonFunction comparison_functions[] = {
+        [](u64 a, u64 b) { return a > b; },  [](u64 a, u64 b) { return a >= b; },
+        [](u64 a, u64 b) { return a < b; },  [](u64 a, u64 b) { return a <= b; },
+        [](u64 a, u64 b) { return a == b; }, [](u64 a, u64 b) { return a != b; },
+    };
+
+    if (cheat.type == CodeType::ConditionalInput) {
+        const auto applet_resource = Core::System::GetInstance()
+                                         .ServiceManager()
+                                         .GetService<Service::HID::Hid>("hid")
+                                         ->GetAppletResource();
+        if (applet_resource == nullptr) {
+            LOG_WARNING(
+                Common_Filesystem,
+                "Attempted to evaluate input conditional, but applet resource is not initialized!");
+            return false;
+        }
+
+        const auto press_state =
+            applet_resource
+                ->GetController<Service::HID::Controller_NPad>(Service::HID::HidController::NPad)
+                .GetPressState();
+        return ((press_state & cheat.KeypadValue()) & KEYPAD_BITMASK) != 0;
+    }
+
+    ASSERT(cheat.type == CodeType::Conditional);
+
+    const auto offset =
+        cheat.memory_type == MemoryType::MainNSO ? main_region_begin : heap_region_begin;
+    ASSERT(static_cast<u8>(cheat.comparison_op.Value()) < 6);
+    const auto* function = comparison_functions[static_cast<u8>(cheat.comparison_op.Value())];
+    const auto addr = cheat.Address() + offset;
+
+    return function(reader(cheat.width, SanitizeAddress(addr)), cheat.ValueWidth(8));
+}
+
+void CheatList::ProcessBlockPairs(const Block& block) {
+    block_pairs.clear();
+
+    u64 scope = 0;
+    std::map<u64, u64> pairs;
+
+    for (std::size_t i = 0; i < block.size(); ++i) {
+        const auto& cheat = block[i];
+
+        switch (cheat.type) {
+        case CodeType::Conditional:
+        case CodeType::ConditionalInput:
+            pairs.insert_or_assign(scope, i);
+            ++scope;
+            break;
+        case CodeType::EndConditional: {
+            --scope;
+            const auto idx = pairs.at(scope);
+            block_pairs.insert_or_assign(idx, i);
+            break;
+        }
+        case CodeType::Loop: {
+            if (cheat.end_of_loop) {
+                --scope;
+                const auto idx = pairs.at(scope);
+                block_pairs.insert_or_assign(idx, i);
+            } else {
+                pairs.insert_or_assign(scope, i);
+                ++scope;
+            }
+            break;
+        }
+        }
+    }
+}
+
+void CheatList::WriteImmediate(const Cheat& cheat) {
+    const auto offset =
+        cheat.memory_type == MemoryType::MainNSO ? main_region_begin : heap_region_begin;
+    auto& register_3 = scratch.at(cheat.register_3);
+
+    const auto addr = cheat.Address() + offset + register_3;
+    LOG_DEBUG(Common_Filesystem, "writing value={:016X} to addr={:016X}", addr,
+              cheat.Value(8, cheat.width));
+    writer(cheat.width, SanitizeAddress(addr), cheat.ValueWidth(8));
+}
+
+void CheatList::BeginConditional(const Cheat& cheat) {
+    if (!EvaluateConditional(cheat)) {
+        const auto iter = block_pairs.find(current_index);
+        ASSERT(iter != block_pairs.end());
+        current_index = iter->second - 1;
+    }
+}
+
+void CheatList::EndConditional(const Cheat& cheat) {
+    LOG_DEBUG(Common_Filesystem, "Ending conditional block.");
+}
+
+void CheatList::Loop(const Cheat& cheat) {
+    if (cheat.end_of_loop.Value())
+        ASSERT(!cheat.end_of_loop.Value());
+
+    auto& register_3 = scratch.at(cheat.register_3);
+    const auto iter = block_pairs.find(current_index);
+    ASSERT(iter != block_pairs.end());
+    ASSERT(iter->first < iter->second);
+
+    for (int i = cheat.Value(4, 4); i >= 0; --i) {
+        register_3 = i;
+        for (std::size_t c = iter->first + 1; c < iter->second; ++c) {
+            current_index = c;
+            ExecuteSingleCheat(
+                (in_standard ? standard_list : master_list)[current_block].second[c]);
+        }
+    }
+
+    current_index = iter->second;
+}
+
+void CheatList::LoadImmediate(const Cheat& cheat) {
+    auto& register_3 = scratch.at(cheat.register_3);
+
+    LOG_DEBUG(Common_Filesystem, "setting register={:01X} equal to value={:016X}", cheat.register_3,
+              cheat.Value(4, 8));
+    register_3 = cheat.Value(4, 8);
+}
+
+void CheatList::LoadIndexed(const Cheat& cheat) {
+    const auto offset =
+        cheat.memory_type == MemoryType::MainNSO ? main_region_begin : heap_region_begin;
+    auto& register_3 = scratch.at(cheat.register_3);
+
+    const auto addr = (cheat.load_from_register.Value() ? register_3 : offset) + cheat.Address();
+    LOG_DEBUG(Common_Filesystem, "writing indexed value to register={:01X}, addr={:016X}",
+              cheat.register_3, addr);
+    register_3 = reader(cheat.width, SanitizeAddress(addr));
+}
+
+void CheatList::StoreIndexed(const Cheat& cheat) {
+    auto& register_3 = scratch.at(cheat.register_3);
+
+    const auto addr =
+        register_3 + (cheat.add_additional_register.Value() ? scratch.at(cheat.register_6) : 0);
+    LOG_DEBUG(Common_Filesystem, "writing value={:016X} to addr={:016X}",
+              cheat.Value(4, cheat.width), addr);
+    writer(cheat.width, SanitizeAddress(addr), cheat.ValueWidth(4));
+}
+
+void CheatList::RegisterArithmetic(const Cheat& cheat) {
+    using ArithmeticFunction = u64 (*)(u64, u64);
+    constexpr ArithmeticFunction arithmetic_functions[] = {
+        [](u64 a, u64 b) { return a + b; },  [](u64 a, u64 b) { return a - b; },
+        [](u64 a, u64 b) { return a * b; },  [](u64 a, u64 b) { return a << b; },
+        [](u64 a, u64 b) { return a >> b; },
+    };
+
+    using ArithmeticOverflowCheck = bool (*)(u64, u64);
+    constexpr ArithmeticOverflowCheck arithmetic_overflow_checks[] = {
+        [](u64 a, u64 b) { return a > (std::numeric_limits<u64>::max() - b); },       // a + b
+        [](u64 a, u64 b) { return a > (std::numeric_limits<u64>::max() + b); },       // a - b
+        [](u64 a, u64 b) { return a > (std::numeric_limits<u64>::max() / b); },       // a * b
+        [](u64 a, u64 b) { return b >= 64 || (a & ~((1ull << (64 - b)) - 1)) != 0; }, // a << b
+        [](u64 a, u64 b) { return b >= 64 || (a & ((1ull << b) - 1)) != 0; },         // a >> b
+    };
+
+    static_assert(sizeof(arithmetic_functions) == sizeof(arithmetic_overflow_checks),
+                  "Missing or have extra arithmetic overflow checks compared to functions!");
+
+    auto& register_3 = scratch.at(cheat.register_3);
+
+    ASSERT(static_cast<u8>(cheat.arithmetic_op.Value()) < 5);
+    const auto* function = arithmetic_functions[static_cast<u8>(cheat.arithmetic_op.Value())];
+    const auto* overflow_function =
+        arithmetic_overflow_checks[static_cast<u8>(cheat.arithmetic_op.Value())];
+    LOG_DEBUG(Common_Filesystem, "performing arithmetic with register={:01X}, value={:016X}",
+              cheat.register_3, cheat.ValueWidth(4));
+
+    if (overflow_function(register_3, cheat.ValueWidth(4))) {
+        LOG_WARNING(Common_Filesystem,
+                    "overflow will occur when performing arithmetic operation={:02X} with operands "
+                    "a={:016X}, b={:016X}!",
+                    static_cast<u8>(cheat.arithmetic_op.Value()), register_3, cheat.ValueWidth(4));
+    }
+
+    register_3 = function(register_3, cheat.ValueWidth(4));
+}
+
+void CheatList::BeginConditionalInput(const Cheat& cheat) {
+    if (!EvaluateConditional(cheat)) {
+        const auto iter = block_pairs.find(current_index);
+        ASSERT(iter != block_pairs.end());
+        current_index = iter->second - 1;
+    }
+}
+
+VAddr CheatList::SanitizeAddress(VAddr in) const {
+    if ((in < main_region_begin || in >= main_region_end) &&
+        (in < heap_region_begin || in >= heap_region_end)) {
+        LOG_ERROR(Common_Filesystem,
+                  "Cheat attempting to access memory at invalid address={:016X}, if this persists, "
+                  "the cheat may be incorrect. However, this may be normal early in execution if "
+                  "the game has not properly set up yet.",
+                  in);
+        return 0; ///< Invalid addresses will hard crash
+    }
+
+    return in;
+}
+
+void CheatList::ExecuteSingleCheat(const Cheat& cheat) {
+    using CheatOperationFunction = void (CheatList::*)(const Cheat&);
+    constexpr CheatOperationFunction cheat_operation_functions[] = {
+        &CheatList::WriteImmediate,        &CheatList::BeginConditional,
+        &CheatList::EndConditional,        &CheatList::Loop,
+        &CheatList::LoadImmediate,         &CheatList::LoadIndexed,
+        &CheatList::StoreIndexed,          &CheatList::RegisterArithmetic,
+        &CheatList::BeginConditionalInput,
+    };
+
+    const auto index = static_cast<u8>(cheat.type.Value());
+    ASSERT(index < sizeof(cheat_operation_functions));
+    const auto op = cheat_operation_functions[index];
+    (this->*op)(cheat);
+}
+
+void CheatList::ExecuteBlock(const Block& block) {
+    encountered_loops.clear();
+
+    ProcessBlockPairs(block);
+    for (std::size_t i = 0; i < block.size(); ++i) {
+        current_index = i;
+        ExecuteSingleCheat(block[i]);
+        i = current_index;
+    }
+}
+
+CheatParser::~CheatParser() = default;
+
+CheatList CheatParser::MakeCheatList(CheatList::ProgramSegment master,
+                                     CheatList::ProgramSegment standard) const {
+    return {master, standard};
+}
+
+TextCheatParser::~TextCheatParser() = default;
+
+CheatList TextCheatParser::Parse(const std::vector<u8>& data) const {
+    std::stringstream ss;
+    ss.write(reinterpret_cast<const char*>(data.data()), data.size());
+
+    std::vector<std::string> lines;
+    std::string stream_line;
+    while (std::getline(ss, stream_line)) {
+        // Remove a trailing \r
+        if (!stream_line.empty() && stream_line.back() == '\r')
+            stream_line.pop_back();
+        lines.push_back(std::move(stream_line));
+    }
+
+    CheatList::ProgramSegment master_list;
+    CheatList::ProgramSegment standard_list;
+
+    for (std::size_t i = 0; i < lines.size(); ++i) {
+        auto line = lines[i];
+
+        if (!line.empty() && (line[0] == '[' || line[0] == '{')) {
+            const auto master = line[0] == '{';
+            const auto begin = master ? line.find('{') : line.find('[');
+            const auto end = master ? line.find_last_of('}') : line.find_last_of(']');
+
+            ASSERT(begin != std::string::npos && end != std::string::npos);
+
+            const std::string patch_name{line.begin() + begin + 1, line.begin() + end};
+            CheatList::Block block{};
+
+            while (i < lines.size() - 1) {
+                line = lines[++i];
+                if (!line.empty() && (line[0] == '[' || line[0] == '{')) {
+                    --i;
+                    break;
+                }
+
+                if (line.size() < 8)
+                    continue;
+
+                Cheat out{};
+                out.raw = ParseSingleLineCheat(line);
+                block.push_back(out);
+            }
+
+            (master ? master_list : standard_list).emplace_back(patch_name, block);
+        }
+    }
+
+    return MakeCheatList(master_list, standard_list);
+}
+
+std::array<u8, 16> TextCheatParser::ParseSingleLineCheat(const std::string& line) const {
+    std::array<u8, 16> out{};
+
+    if (line.size() < 8)
+        return out;
+
+    const auto word1 = Common::HexStringToArray<sizeof(u32)>(std::string_view{line.data(), 8});
+    std::memcpy(out.data(), word1.data(), sizeof(u32));
+
+    if (line.size() < 17 || line[8] != ' ')
+        return out;
+
+    const auto word2 = Common::HexStringToArray<sizeof(u32)>(std::string_view{line.data() + 9, 8});
+    std::memcpy(out.data() + sizeof(u32), word2.data(), sizeof(u32));
+
+    if (line.size() < 26 || line[17] != ' ') {
+        // Perform shifting in case value is truncated early.
+        const auto type = static_cast<CodeType>((out[0] & 0xF0) >> 4);
+        if (type == CodeType::Loop || type == CodeType::LoadImmediate ||
+            type == CodeType::StoreIndexed || type == CodeType::RegisterArithmetic) {
+            std::memcpy(out.data() + 8, out.data() + 4, sizeof(u32));
+            std::memset(out.data() + 4, 0, sizeof(u32));
+        }
+
+        return out;
+    }
+
+    const auto word3 = Common::HexStringToArray<sizeof(u32)>(std::string_view{line.data() + 18, 8});
+    std::memcpy(out.data() + 2 * sizeof(u32), word3.data(), sizeof(u32));
+
+    if (line.size() < 35 || line[26] != ' ') {
+        // Perform shifting in case value is truncated early.
+        const auto type = static_cast<CodeType>((out[0] & 0xF0) >> 4);
+        if (type == CodeType::WriteImmediate || type == CodeType::Conditional) {
+            std::memcpy(out.data() + 12, out.data() + 8, sizeof(u32));
+            std::memset(out.data() + 8, 0, sizeof(u32));
+        }
+
+        return out;
+    }
+
+    const auto word4 = Common::HexStringToArray<sizeof(u32)>(std::string_view{line.data() + 27, 8});
+    std::memcpy(out.data() + 3 * sizeof(u32), word4.data(), sizeof(u32));
+
+    return out;
+}
+
+u64 MemoryReadImpl(u8 width, VAddr addr) {
+    switch (width) {
+    case 1:
+        return Memory::Read8(addr);
+    case 2:
+        return Memory::Read16(addr);
+    case 4:
+        return Memory::Read32(addr);
+    case 8:
+        return Memory::Read64(addr);
+    default:
+        UNREACHABLE();
+        return 0;
+    }
+}
+
+void MemoryWriteImpl(u8 width, VAddr addr, u64 value) {
+    switch (width) {
+    case 1:
+        Memory::Write8(addr, static_cast<u8>(value));
+        break;
+    case 2:
+        Memory::Write16(addr, static_cast<u16>(value));
+        break;
+    case 4:
+        Memory::Write32(addr, static_cast<u32>(value));
+        break;
+    case 8:
+        Memory::Write64(addr, value);
+        break;
+    default:
+        UNREACHABLE();
+    }
+}
+
+CheatEngine::CheatEngine(std::vector<CheatList> cheats, const std::string& build_id)
+    : cheats(std::move(cheats)) {
+    event = CoreTiming::RegisterEvent(
+        "CheatEngine::FrameCallback::" + build_id,
+        [this](u64 userdata, s64 cycles_late) { FrameCallback(userdata, cycles_late); });
+    CoreTiming::ScheduleEvent(CHEAT_ENGINE_TICKS, event);
+
+    const auto& vm_manager = Core::System::GetInstance().CurrentProcess()->VMManager();
+    for (auto& list : this->cheats) {
+        list.SetMemoryParameters(
+            vm_manager.GetMainCodeRegionBaseAddress(), vm_manager.GetHeapRegionBaseAddress(),
+            vm_manager.GetMainCodeRegionEndAddress(), vm_manager.GetHeapRegionEndAddress(),
+            &MemoryWriteImpl, &MemoryReadImpl);
+    }
+}
+
+CheatEngine::~CheatEngine() {
+    CoreTiming::UnscheduleEvent(event, 0);
+}
+
+void CheatEngine::FrameCallback(u64 userdata, int cycles_late) {
+    for (auto& list : cheats)
+        list.Execute();
+
+    CoreTiming::ScheduleEvent(CHEAT_ENGINE_TICKS - cycles_late, event);
+}
+
+} // namespace FileSys
diff --git a/src/core/file_sys/cheat_engine.h b/src/core/file_sys/cheat_engine.h
new file mode 100644
index 000000000..d7a8654b7
--- /dev/null
+++ b/src/core/file_sys/cheat_engine.h
@@ -0,0 +1,226 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <map>
+#include <set>
+#include <vector>
+#include <queue>
+#include "common/bit_field.h"
+#include "common/common_types.h"
+
+namespace CoreTiming {
+struct EventType;
+}
+
+namespace FileSys {
+
+enum class CodeType : u32 {
+    // 0TMR00AA AAAAAAAA YYYYYYYY YYYYYYYY
+    // Writes a T sized value Y to the address A added to the value of register R in memory domain M
+    WriteImmediate = 0,
+
+    // 1TMC00AA AAAAAAAA YYYYYYYY YYYYYYYY
+    // Compares the T sized value Y to the value at address A in memory domain M using the
+    // conditional function C. If success, continues execution. If failure, jumps to the matching
+    // EndConditional statement.
+    Conditional = 1,
+
+    // 20000000
+    // Terminates a Conditional or ConditionalInput block.
+    EndConditional = 2,
+
+    // 300R0000 VVVVVVVV
+    // Starts looping V times, storing the current count in register R.
+    // Loop block is terminated with a matching 310R0000.
+    Loop = 3,
+
+    // 400R0000 VVVVVVVV VVVVVVVV
+    // Sets the value of register R to the value V.
+    LoadImmediate = 4,
+
+    // 5TMRI0AA AAAAAAAA
+    // Sets the value of register R to the value of width T at address A in memory domain M, with
+    // the current value of R added to the address if I == 1.
+    LoadIndexed = 5,
+
+    // 6T0RIFG0 VVVVVVVV VVVVVVVV
+    // Writes the value V of width T to the memory address stored in register R. Adds the value of
+    // register G to the final calculation if F is nonzero. Increments the value of register R by T
+    // after operation if I is nonzero.
+    StoreIndexed = 6,
+
+    // 7T0RA000 VVVVVVVV
+    // Performs the arithmetic operation A on the value in register R and the value V of width T,
+    // storing the result in register R.
+    RegisterArithmetic = 7,
+
+    // 8KKKKKKK
+    // Checks to see if any of the buttons defined by the bitmask K are pressed. If any are,
+    // execution continues. If none are, execution skips to the next EndConditional command.
+    ConditionalInput = 8,
+};
+
+enum class MemoryType : u32 {
+    // Addressed relative to start of main NSO
+    MainNSO = 0,
+
+    // Addressed relative to start of heap
+    Heap = 1,
+};
+
+enum class ArithmeticOp : u32 {
+    Add = 0,
+    Sub = 1,
+    Mult = 2,
+    LShift = 3,
+    RShift = 4,
+};
+
+enum class ComparisonOp : u32 {
+    GreaterThan = 1,
+    GreaterThanEqual = 2,
+    LessThan = 3,
+    LessThanEqual = 4,
+    Equal = 5,
+    Inequal = 6,
+};
+
+union Cheat {
+    std::array<u8, 16> raw;
+
+    BitField<4, 4, CodeType> type;
+    BitField<0, 4, u32> width; // Can be 1, 2, 4, or 8. Measured in bytes.
+    BitField<0, 4, u32> end_of_loop;
+    BitField<12, 4, MemoryType> memory_type;
+    BitField<8, 4, u32> register_3;
+    BitField<8, 4, ComparisonOp> comparison_op;
+    BitField<20, 4, u32> load_from_register;
+    BitField<20, 4, u32> increment_register;
+    BitField<20, 4, ArithmeticOp> arithmetic_op;
+    BitField<16, 4, u32> add_additional_register;
+    BitField<28, 4, u32> register_6;
+
+    u64 Address() const;
+    u64 ValueWidth(u64 offset) const;
+    u64 Value(u64 offset, u64 width) const;
+    u32 KeypadValue() const;
+};
+
+class CheatParser;
+
+// Represents a full collection of cheats for a game. The Execute function should be called every
+// interval that all cheats should be executed. Clients should not directly instantiate this class
+// (hence private constructor), they should instead receive an instance from CheatParser, which
+// guarantees the list is always in an acceptable state.
+class CheatList {
+public:
+    friend class CheatParser;
+
+    using Block = std::vector<Cheat>;
+    using ProgramSegment = std::vector<std::pair<std::string, Block>>;
+
+    // (width in bytes, address, value)
+    using MemoryWriter = void (*)(u8, VAddr, u64);
+    // (width in bytes, address) -> value
+    using MemoryReader = u64 (*)(u8, VAddr);
+
+    void SetMemoryParameters(VAddr main_begin, VAddr heap_begin, VAddr main_end, VAddr heap_end,
+                             MemoryWriter writer, MemoryReader reader);
+
+    void Execute();
+
+private:
+    CheatList(ProgramSegment master, ProgramSegment standard);
+
+    void ProcessBlockPairs(const Block& block);
+    void ExecuteSingleCheat(const Cheat& cheat);
+
+    void ExecuteBlock(const Block& block);
+
+    bool EvaluateConditional(const Cheat& cheat) const;
+
+    // Individual cheat operations
+    void WriteImmediate(const Cheat& cheat);
+    void BeginConditional(const Cheat& cheat);
+    void EndConditional(const Cheat& cheat);
+    void Loop(const Cheat& cheat);
+    void LoadImmediate(const Cheat& cheat);
+    void LoadIndexed(const Cheat& cheat);
+    void StoreIndexed(const Cheat& cheat);
+    void RegisterArithmetic(const Cheat& cheat);
+    void BeginConditionalInput(const Cheat& cheat);
+
+    VAddr SanitizeAddress(VAddr in) const;
+
+    // Master Codes are defined as codes that cannot be disabled and are run prior to all
+    // others.
+    ProgramSegment master_list;
+    // All other codes
+    ProgramSegment standard_list;
+
+    bool in_standard = false;
+
+    // 16 (0x0-0xF) scratch registers that can be used by cheats
+    std::array<u64, 16> scratch{};
+
+    MemoryWriter writer = nullptr;
+    MemoryReader reader = nullptr;
+
+    u64 main_region_begin{};
+    u64 heap_region_begin{};
+    u64 main_region_end{};
+    u64 heap_region_end{};
+
+    u64 current_block{};
+    // The current index of the cheat within the current Block
+    u64 current_index{};
+
+    // The 'stack' of the program. When a conditional or loop statement is encountered, its index is
+    // pushed onto this queue. When a end block is encountered, the condition is checked.
+    std::map<u64, u64> block_pairs;
+
+    std::set<u64> encountered_loops;
+};
+
+// Intermediary class that parses a text file or other disk format for storing cheats into a
+// CheatList object, that can be used for execution.
+class CheatParser {
+public:
+    virtual ~CheatParser();
+
+    virtual CheatList Parse(const std::vector<u8>& data) const = 0;
+
+protected:
+    CheatList MakeCheatList(CheatList::ProgramSegment master,
+                            CheatList::ProgramSegment standard) const;
+};
+
+// CheatParser implementation that parses text files
+class TextCheatParser final : public CheatParser {
+public:
+    ~TextCheatParser() override;
+
+    CheatList Parse(const std::vector<u8>& data) const override;
+
+private:
+    std::array<u8, 16> ParseSingleLineCheat(const std::string& line) const;
+};
+
+// Class that encapsulates a CheatList and manages its interaction with memory and CoreTiming
+class CheatEngine final {
+public:
+    CheatEngine(std::vector<CheatList> cheats, const std::string& build_id);
+    ~CheatEngine();
+
+private:
+    void FrameCallback(u64 userdata, int cycles_late);
+
+    CoreTiming::EventType* event;
+
+    std::vector<CheatList> cheats;
+};
+
+} // namespace FileSys