xref: /Renode-Infrastructure-v1.15.3-29f510e/src/Emulator/Main/Peripherals/Bus/SystemBus.cs

//
// Copyright (c) 2010-2025 Antmicro
// Copyright (c) 2011-2015 Realtime Embedded
//
// This file is licensed under the MIT License.
// Full license text is available in 'licenses/MIT.txt'.
//
using System;
using System.Linq;
using System.Globalization;
using System.Collections.Generic;
using Antmicro.Renode.Core;
using Antmicro.Renode.Core.Structure;
using Antmicro.Renode.Exceptions;
using Antmicro.Renode.Logging;
using Antmicro.Renode.Peripherals.Bus.Wrappers;
using Antmicro.Renode.Peripherals.CPU;
using Antmicro.Renode.Utilities;
using System.Threading;
using System.Collections.ObjectModel;
using System.Text;
using Machine = Antmicro.Renode.Core.Machine;
using Antmicro.Migrant;
using Antmicro.Migrant.Hooks;
using ELFSharp.ELF;
using ELFSharp.ELF.Segments;
using ELFSharp.UImage;
using System.IO;
using Antmicro.Renode.Core.Extensions;
using System.Reflection;
using Antmicro.Renode.UserInterface;
using Antmicro.Renode.Peripherals.Memory;

using Range = Antmicro.Renode.Core.Range;

namespace Antmicro.Renode.Peripherals.Bus
{
    /// <summary>
    ///     The <c>SystemBus</c> is the main system class, where all data passes through.
    /// </summary>
    [Icon("sysbus")]
    [ControllerMask(typeof(IPeripheral))]
    public sealed partial class SystemBus : IBusController, IDisposable
    {
        internal SystemBus(IMachine machine)
        {
            this.Machine = machine;
            cpuSync = new object();
            binaryFingerprints = new List<BinaryFingerprint>();
            cpuById = new Dictionary<int, ICPU>();
            idByCpu = new Dictionary<ICPU, int>();
            hooksOnRead = new Dictionary<ulong, List<BusHookHandler>>();
            hooksOnWrite = new Dictionary<ulong, List<BusHookHandler>>();
            pcCache.OnChanged += HandleChangedSymbols;
            InitStructures();
            this.Log(LogLevel.Info, "System bus created.");
        }

        public void LoadFileChunks(string path, IEnumerable<FileChunk> chunks, ICPU cpu)
        {
            var minAddr = this.LoadFileChunks(chunks, cpu);
            AddFingerprint(path);
            UpdateLowestLoadedAddress(minAddr);
            this.DebugLog(path + " File loaded.");
        }

        public void Unregister(IBusPeripheral peripheral)
        {
            using(Machine.ObtainPausedState(true))
            {
                Machine.UnregisterAsAChildOf(this, peripheral);
                UnregisterInner(peripheral);
            }
        }

        public void Unregister(IBusRegistered<IBusPeripheral> busRegisteredPeripheral)
        {
            using(Machine.ObtainPausedState(true))
            {
                Machine.UnregisterAsAChildOf(this, busRegisteredPeripheral.RegistrationPoint);
                UnregisterInner(busRegisteredPeripheral);
            }
        }

        public void Unregister(IPeripheral peripheral)
        {
            using(Machine.ObtainPausedState(true))
            {
                Machine.UnregisterAsAChildOf(this, peripheral);
                RemoveContextKeys(peripheral);
            }
        }

        public void Register(IPeripheral peripheral, NullRegistrationPoint registrationPoint)
        {
            using(Machine.ObtainPausedState(true))
            {
                // NullRegistrationPoint peripherals are not mapped on the bus and
                // are not directly accessible from the emulated software.
                Machine.RegisterAsAChildOf(this, peripheral, registrationPoint);
            }
        }

        public void Register(IBusPeripheral peripheral, BusRangeRegistration registrationPoint)
        {
            var methods = PeripheralAccessMethods.CreateWithLock();
            if(registrationPoint is BusParametrizedRegistration parametrizedRegistrationPoint)
            {
                parametrizedRegistrationPoint.RegisterForEachContext((contextRegistration) =>
                {
                    // Prepare accessor methods in the context of registration,
                    // as it may want to fill them according to the CPU context.
                    methods = PeripheralAccessMethods.CreateWithLock();
                    contextRegistration.FillAccessMethods(peripheral, ref methods);
                    FillAccessMethodsWithDefaultMethods(peripheral, ref methods);
                    RegisterInner(peripheral, methods, contextRegistration, context: contextRegistration.Initiator);
                });
            }
            else if(registrationPoint is BusMultiRegistration multiRegistrationPoint)
            {
                if(peripheral is IMapped)
                {
                    throw new ConstructionException(string.Format("It is not allowed to register `{0}` peripheral using `{1}`", typeof(IMapped).Name, typeof(BusMultiRegistration).Name));
                }
                FillAccessMethodsWithTaggedMethods(peripheral, multiRegistrationPoint.ConnectionRegionName, ref methods);
                multiRegistrationPoint.RegisterForEachContext((contextRegistration) => RegisterInner(peripheral, methods, contextRegistration, context: contextRegistration.Initiator));
            }
            else
            {
                FillAccessMethodsWithDefaultMethods(peripheral, ref methods);
                registrationPoint.RegisterForEachContext((contextRegistration) => RegisterInner(peripheral, methods, contextRegistration, context: contextRegistration.Initiator));
            }
        }

        public void Register(IBusPeripheral peripheral, BusMultiRegistration registrationPoint)
        {
            Register(peripheral, (BusRangeRegistration)registrationPoint);
        }

        public void Register(IBusPeripheral peripheral, BusParametrizedRegistration registrationPoint)
        {
            Register(peripheral, (BusRangeRegistration)registrationPoint);
        }

        void IPeripheralRegister<IBusPeripheral, BusMultiRegistration>.Unregister(IBusPeripheral peripheral)
        {
            Unregister(peripheral);
        }

        public void Register(IKnownSize peripheral, BusPointRegistration registrationPoint)
        {
            Register(peripheral, registrationPoint.ToRangeRegistration(checked((ulong)peripheral.Size)));
        }

        public void Unregister(IKnownSize peripheral)
        {
            Unregister((IBusPeripheral)peripheral);
        }

        public void MoveRegistrationWithinContext(IBusPeripheral peripheral, BusRangeRegistration newRegistration, ICPU context, Func<IEnumerable<IBusRegistered<IBusPeripheral>>, IBusRegistered<IBusPeripheral>> selector = null)
        {
            if(context == null && !TryFindCurrentThreadCPUAndId(out context, out var _))
            {
                throw new RecoverableException("Moving a peripheral is supported only from CPU thread if context isn't explicitly set");
            }
            var wasMapped = RemoveMappingsForPeripheral(peripheral);
            var busRegisteredEntries = peripheralsCollectionByContext[context].Peripherals.Where(x => x.Peripheral == peripheral).ToList();
            if(busRegisteredEntries.Count == 0)
            {
                throw new RecoverableException("Attempted to move a peripheral that isn't registered within current context");
            }
            IBusRegistered<IBusPeripheral> busRegistered;
            if(selector != null)
            {
                busRegistered = selector(busRegisteredEntries);
                if(busRegistered == null)
                {
                    throw new RecoverableException("Provided selector failed to find a suitable registration point");
                }
            }
            else
            {
                if(busRegisteredEntries.Count > 1)
                {
                    throw new RecoverableException($"Unable to unambiguously determine a registration point, found multiple candidates: {String.Join(", ", busRegisteredEntries.Select(x => x.RegistrationPoint))}");
                }
                busRegistered = busRegisteredEntries[0];
            }
            if(IsAddressRangeLocked(busRegistered.RegistrationPoint.Range, context))
            {
                throw new RecoverableException("Moving a peripheral to a locked address range is not supported");
            }
            UnregisterAccessFlags(busRegistered.RegistrationPoint, context);
            peripheralsCollectionByContext.WithStateCollection(context, null, collection =>
            {
                collection.Move(busRegistered, newRegistration);
            });
            Machine.ExchangeRegistrationPointForPeripheral(this, peripheral, busRegistered.RegistrationPoint, newRegistration);
            if(wasMapped)
            {
                AddMappingsForPeripheral(peripheral, newRegistration, context);
            }

            if(peripheral is ArrayMemory)
            {
                foreach(var cpu in GetCPUsForContext<ICPUWithMappedMemory>(context))
                {
                    var range = newRegistration.Range;
                    cpu.RegisterAccessFlags(range.StartAddress, range.Size, isIoMemory: true);
                }
            }
        }

        public void Register(ICPU cpu, CPURegistrationPoint registrationPoint)
        {
            lock(cpuSync)
            {
                if(mappingsRemoved)
                {
                    throw new RegistrationException("Currently cannot register CPU after some memory mappings have been dynamically removed.");
                }
                if(!registrationPoint.Slot.HasValue)
                {
                    var i = 0;
                    while(cpuById.ContainsKey(i))
                    {
                        i++;
                    }
                    registrationPoint = new CPURegistrationPoint(i);
                }
                Machine.RegisterAsAChildOf(this, cpu, registrationPoint);
                cpuById.Add(registrationPoint.Slot.Value, cpu);
                idByCpu.Add(cpu, registrationPoint.Slot.Value);
                AddContextKeys(cpu);
                if(cpu is ICPUWithMappedMemory memoryMappedCpu)
                {
                    foreach(var mapping in mappingsForPeripheral.SelectMany(x => x.Value)
                            .Where(x => x.Context == null || x.Context == cpu))
                    {
                        memoryMappedCpu.MapMemory(mapping);
                    }
                }

                if(cpu.Endianness != Endianess)
                {
                    hasCpuWithMismatchedEndianness = true;
                    UpdateAccessMethods();
                }

                if(GetCPUs().Select(x => x.Endianness).Distinct().Count() > 1)
                {
                    throw new RegistrationException("Currently there can't be CPUs with different endiannesses on the same bus.");
                }
            }
        }

        public void Unregister(ICPU cpu)
        {
            using(Machine.ObtainPausedState(true))
            {
                Machine.UnregisterFromParent(cpu);
                lock(cpuSync)
                {
                    var id = idByCpu[cpu];
                    idByCpu.Remove(cpu);
                    cpuById.Remove(id);
                    RemoveContextKeys(cpu);
                }
            }
        }

        public void SetPCOnAllCores(ulong pc)
        {
            using(Machine.ObtainPausedState(true))
            {
                lock(cpuSync)
                {
                    foreach(var p in idByCpu.Keys.Cast<ICPU>())
                    {
                        p.PC = pc;
                    }
                }
            }
        }

        public void LogAllPeripheralsAccess(bool enable = true)
        {
            lock(cpuSync)
            {
                foreach(var p in allPeripherals.SelectMany(x => x.Peripherals))
                {
                    LogPeripheralAccess(p.Peripheral, enable);
                }
            }
        }

        public void LogPeripheralAccess(IBusPeripheral busPeripheral, bool enable = true)
        {
            foreach(var peripherals in allPeripherals)
            {
                peripherals.VisitAccessMethods(busPeripheral, pam =>
                {
                    // first check whether logging is already enabled, method should be idempotent
                    var loggingAlreadEnabled = pam.WriteByte.Target is HookWrapper;
                    this.Log(LogLevel.Info, "Logging already enabled: {0}.", loggingAlreadEnabled);
                    if(enable == loggingAlreadEnabled)
                    {
                        return pam;
                    }
                    if(enable)
                    {
                        pam.WrapMethods(typeof(ReadLoggingWrapper<>), typeof(WriteLoggingWrapper<>));
                        return pam;
                    }
                    else
                    {
                        pam.RemoveWrappersOfType(typeof(ReadLoggingWrapper<>), typeof(WriteLoggingWrapper<>));
                        return pam;
                    }
                });
            }
        }

        public void EnableAllTranslations(bool enable = true)
        {
            foreach(var p in allPeripherals.SelectMany(x => x.Peripherals))
            {
                EnableAllTranslations(p.Peripheral, enable);
            }
        }

        public void EnableAllTranslations(IBusPeripheral busPeripheral, bool enable = true)
        {
            foreach(var peripherals in allPeripherals)
            {
                peripherals.VisitAccessMethods(busPeripheral, pam =>
                {
                    pam.EnableAllTranslations(enable, Endianess);
                    return pam;
                });
            }
        }

        public IEnumerable<ICPU> GetCPUs()
        {
            lock(cpuSync)
            {
                return new ReadOnlyCollection<ICPU>(idByCpu.Keys.ToList());
            }
        }

        public int GetCPUSlot(ICPU cpu)
        {
            lock(cpuSync)
            {
                if(idByCpu.ContainsKey(cpu))
                {
                    return idByCpu[cpu];
                }
                throw new KeyNotFoundException("Given CPU is not registered.");
            }
        }

        public ICPU GetCurrentCPU()
        {
            ICPU cpu;
            if(!TryGetCurrentCPU(out cpu))
            {
                // TODO: inline
                throw new RecoverableException(CantFindCpuIdMessage);
            }
            return cpu;
        }

        public int GetCurrentCPUId()
        {
            int id;
            if(!TryGetCurrentCPUId(out id))
            {
                throw new RecoverableException(CantFindCpuIdMessage);
            }
            return id;
        }

        public IEnumerable<IPeripheral> GetAllContextKeys()
        {
            return peripheralsCollectionByContext.GetAllContextKeys();
        }

        public bool TryGetCurrentContextState<T>(out IPeripheralWithTransactionState cpu, out T cpuState)
        {
            cpu = null;
            cpuState = default;
            if(!threadLocalContext.InUse || !threadLocalContext.InitiatorState.HasValue)
            {
                return false;
            }
            cpu = threadLocalContext.Initiator as IPeripheralWithTransactionState;
            if((cpu == null) || !cpu.TryConvertUlongToStateObj(threadLocalContext.InitiatorState.Value, out var state))
            {
                return false;
            }
            if(state is T requestedTypeSTate)
            {
                cpuState = requestedTypeSTate;
                return true;
            }
            return false;
        }

        public bool TryConvertStateToUlongForContext(IPeripheral context, IContextState cpuStateObj, out ulong? state)
        {
            state = null;
            if(!(context is IPeripheralWithTransactionState peripheralWithTransactionState)
                || !peripheralWithTransactionState.TryConvertStateObjToUlong(cpuStateObj, out state))
            {
                return false;
            }
            return true;
        }

        private void HandleChangedSymbols()
        {
            OnSymbolsChanged?.Invoke(Machine);
        }

        private IEnumerable<ICPU> GetCPUsForContext(IPeripheral context)
        {
            return GetCPUs().Where(x => context == null || x == context);
        }

        private IEnumerable<T> GetCPUsForContext<T>(IPeripheral context)
            where T : IPeripheral
        {
            return GetCPUsForContext(context).OfType<T>();
        }

        private bool TryGetCurrentCPUId(out int cpuId)
        {
            if(threadLocalContext.InUse && threadLocalContext.Initiator is ICPU cpu)
            {
                cpuId = idByCpu[cpu];
                return true;
            }
            /*
             * Because getting cpu id can possibly be a heavy operation, we cache the
             * obtained ID in the thread local storage. Note that we assume here that the
             * thread with such storage won't be used for another purposes than it was
             * used originally (i.e. cpu loop).
             */
            if(cachedCpuId.IsValueCreated)
            {
                cpuId = cachedCpuId.Value;
                return true;
            }

            return TryFindCurrentThreadCPUAndId(out var _, out cpuId);
        }

        private bool TryFindCurrentThreadCPUAndId(out ICPU cpu, out int cpuId)
        {
            lock(cpuSync)
            {
                foreach(var entry in cpuById)
                {
                    cpu = entry.Value;
                    if(!cpu.OnPossessedThread)
                    {
                        continue;
                    }
                    cpuId = entry.Key;
                    cachedCpuId.Value = cpuId;
                    return true;
                }
                cpu = default(ICPU);
                cpuId = -1;
                return false;
            }
        }

        public bool TryGetCurrentCPU(out ICPU cpu)
        {
            lock(cpuSync)
            {
                int id;
                if(TryGetCurrentCPUId(out id))
                {
                    cpu = cpuById[id];
                    return true;
                }
                cpu = null;
                return false;
            }
        }

        /// <summary>
        /// Unregister peripheral from the specified address.
        ///
        /// NOTE: After calling this method, peripheral may still be
        /// registered in the SystemBus at another address. In order
        /// to remove peripheral completely use 'Unregister' method.
        /// </summary>
        /// <param name="address">Address on system bus where the peripheral is registered.</param>
        /// <param name="context">
        ///     CPU context in which peripherals should be scanned.
        ///     This is useful when some peripherals are only accessible from selected CPUs.
        ///
        ///     If not provided, the global peripherals collection (i.e., peripherals available for all CPUs) is searched.
        /// </param>
        public void UnregisterFromAddress(ulong address, ICPU context = null)
        {
            var busRegisteredPeripheral = WhatIsAt(address, context);
            if(busRegisteredPeripheral == null)
            {
                throw new RecoverableException(string.Format(
                    "There is no peripheral registered at 0x{0:X}.", address));
            }
            Unregister(busRegisteredPeripheral);
        }

        public void Dispose()
        {
            cachedCpuId.Dispose();
            threadLocalContext.Dispose();
            globalLookup.Dispose();
            foreach(var lookup in localLookups.Values)
            {
                lookup.Dispose();
            }
            #if DEBUG
            foreach(var peripherals in allPeripherals)
            {
                peripherals.ShowStatistics();
            }
            #endif
        }

        /// <summary>Checks what is at a given address.</summary>
        /// <param name="address">
        ///     A <see cref="ulong"/> with the address to check.
        /// </param>
        /// <param name="context">
        ///     CPU context in which peripherals should be scanned.
        ///     This is useful when some peripherals are only accessible from selected CPUs.
        ///
        ///     If not provided, the global peripherals collection (i.e., peripherals available for all CPUs) is searched.
        /// </param>
        /// <returns>
        ///     A peripheral which is at the given address.
        /// </returns>
        public IBusRegistered<IBusPeripheral> WhatIsAt(ulong address, IPeripheral context = null)
        {
            return GetAccessiblePeripheralsForContext(context).FirstOrDefault(x => x.RegistrationPoint.Range.Contains(address));
        }

        public IPeripheral WhatPeripheralIsAt(ulong address, IPeripheral context = null)
        {
            var registered = WhatIsAt(address, context);
            if(registered != null)
            {
                return registered.Peripheral;
            }
            return null;
        }

        public IBusRegistered<MappedMemory> FindMemory(ulong address, ICPU context = null)
        {
            return GetAccessiblePeripheralsForContext(context)
                .Where(x => x.Peripheral is MappedMemory)
                .Convert<IBusPeripheral, MappedMemory>()
                .FirstOrDefault(x => x.RegistrationPoint.Range.Contains(address));
        }

        public bool IsMemory(ulong address, ICPU context = null)
        {
            return GetAccessiblePeripheralsForContext(context)
                .Any(x => x.Peripheral is IMemory && x.RegistrationPoint.Range.Contains(address));
        }

        public IEnumerable<IBusRegistered<IMapped>> GetMappedPeripherals(IPeripheral context = null)
        {
            return GetAccessiblePeripheralsForContext(context)
                .Where(x => x.Peripheral is IMapped)
                .Convert<IBusPeripheral, IMapped>();
        }

        public IEnumerable<IBusRegistered<IBusPeripheral>> GetRegistrationsForPeripheralType<T>(IPeripheral context = null)
        {
            return GetAccessiblePeripheralsForContext(context)
                .Where(x => x.Peripheral is T);
        }

        public IEnumerable<IBusRegistered<IBusPeripheral>> GetRegisteredPeripherals(IPeripheral context = null)
        {
            return GetAccessiblePeripheralsForContext(context);
        }

        public void SilenceRange(Range range)
        {
            var silencer = new Silencer();
            Register(silencer, new BusRangeRegistration(range));
        }

        public void ReadBytes(ulong address, int count, byte[] destination, int startIndex, bool onlyMemory = false, IPeripheral context = null)
        {
            using(SetLocalContext(context))
            {
                var targets = FindTargets(address, checked((ulong)count), context);
                if(onlyMemory)
                {
                    ThrowIfNotAllMemory(targets);
                }
                foreach(var target in targets)
                {
                    var memory = target.What.Peripheral as MappedMemory;
                    if(memory != null)
                    {
                        checked
                        {
                            memory.ReadBytes(checked((long)(target.Offset - target.What.RegistrationPoint.Range.StartAddress + target.What.RegistrationPoint.Offset)), (int)target.SourceLength, destination, startIndex + (int)target.SourceIndex);
                        }
                    }
                    else
                    {
                        for(var i = 0UL; i < target.SourceLength; ++i)
                        {
                            destination[checked((ulong)startIndex) + target.SourceIndex + i] = ReadByte(target.Offset + i, context);
                        }
                    }
                }
            }
        }

        public byte[] ReadBytes(ulong address, int count, bool onlyMemory = false, IPeripheral context = null)
        {
            var result = new byte[count];
            ReadBytes(address, count, result, 0, onlyMemory, context);
            return result;
        }

        public byte[] ReadBytes(long offset, int count, IPeripheral context = null)
        {
            return ReadBytes((ulong)offset, count, context: context);
        }

        public void WriteBytes(byte[] bytes, ulong address, bool onlyMemory = false, IPeripheral context = null)
        {
            WriteBytes(bytes, address, bytes.Length, onlyMemory, context);
        }

        public void WriteBytes(byte[] bytes, ulong address, int startingIndex, long count, bool onlyMemory = false, IPeripheral context = null)
        {
            using(SetLocalContext(context))
            {
                var targets = FindTargets(address, checked((ulong)count), context);
                if(onlyMemory)
                {
                    ThrowIfNotAllMemory(targets);
                }
                foreach(var target in targets)
                {
                    var multibytePeripheral = target.What.Peripheral as IMultibyteWritePeripheral;
                    if(multibytePeripheral != null)
                    {
                        checked
                        {
                            multibytePeripheral.WriteBytes(checked((long)(target.Offset - target.What.RegistrationPoint.Range.StartAddress + target.What.RegistrationPoint.Offset)), bytes, startingIndex + (int)target.SourceIndex, (int)target.SourceLength);
                        }
                    }
                    else
                    {
                        for(var i = 0UL; i < target.SourceLength; ++i)
                        {
                            WriteByte(target.Offset + i, bytes[target.SourceIndex + (ulong)startingIndex + i]);
                        }
                    }
                }
            }
        }

        public void WriteBytes(byte[] bytes, ulong address, long count, bool onlyMemory = false, IPeripheral context = null)
        {
            WriteBytes(bytes, address, 0, count, onlyMemory, context);
        }

        public void WriteBytes(long offset, byte[] array, int startingIndex, int count, IPeripheral context = null)
        {
            WriteBytes(array, (ulong)offset, startingIndex, count, context: context);
        }

        public void ZeroRange(Range range, IPeripheral context = null)
        {
            var zeroBlock = new byte[1024 * 1024];
            var blocksNo = range.Size / (ulong)zeroBlock.Length;
            for(var i = 0UL; i < blocksNo; i++)
            {
                WriteBytes(zeroBlock, range.StartAddress + i * (ulong)zeroBlock.Length, context: context);
            }
            WriteBytes(zeroBlock, range.StartAddress + blocksNo * (ulong)zeroBlock.Length, (int)range.Size % zeroBlock.Length, context: context);
        }

        // Specifying `textAddress` will override the address of the program text - the symbols will be applied
        // as if the first loaded segment started at the specified address. This is equivalent to the ADDR parameter
        // to GDB's add-symbol-file.
        public void LoadSymbolsFrom(IELF elf, bool useVirtualAddress = false, ulong? textAddress = null, ICPU context = null)
        {
            GetOrCreateLookup(context).LoadELF(elf, useVirtualAddress, textAddress);
            pcCache.Invalidate();
        }

        public void ClearSymbols(ICPU context = null)
        {
            RemoveLookup(context);
            pcCache.Invalidate();
        }

        public void AddSymbol(Range address, string name, bool isThumb = false, ICPU context = null)
        {
            checked
            {
                GetOrCreateLookup(context).InsertSymbol(name, address.StartAddress, address.Size);
            }
            pcCache.Invalidate();
        }

        public void LoadUImage(ReadFilePath fileName, IInitableCPU cpu = null)
        {
            if(!Machine.IsPaused)
            {
                throw new RecoverableException("Cannot load ELF on an unpaused machine.");
            }
            UImage uImage;
            this.DebugLog("Loading uImage {0}.", fileName);

            switch(UImageReader.TryLoad(fileName, out uImage))
            {
            case UImageResult.NotUImage:
                throw new RecoverableException(string.Format("Given file '{0}' is not a U-Boot image.", fileName));
            case UImageResult.BadChecksum:
                throw new RecoverableException(string.Format("Header checksum does not match for the U-Boot image '{0}'.", fileName));
            case UImageResult.NotSupportedImageType:
                throw new RecoverableException(string.Format("Given file '{0}' is not of a supported image type.", fileName));
            }
            byte[] toLoad;
            switch(uImage.TryGetImageData(out toLoad))
            {
            case ImageDataResult.BadChecksum:
                throw new RecoverableException("Bad image checksum, probably corrupted image.");
            case ImageDataResult.UnsupportedCompressionFormat:
                throw new RecoverableException(string.Format("Unsupported compression format '{0}'.", uImage.Compression));
            }
            WriteBytes(toLoad, uImage.LoadAddress, context: cpu);
            if(cpu != null)
            {
                cpu.InitFromUImage(uImage);
            }
            else
            {
                foreach(var c in GetCPUs().OfType<IInitableCPU>())
                {
                    c.InitFromUImage(uImage);
                }
            }
            this.Log(LogLevel.Info, string.Format(
                "Loaded U-Boot image '{0}'\n" +
                "load address: 0x{1:X}\n" +
                "size:         {2}B = {3}B\n" +
                "timestamp:    {4}\n" +
                "entry point:  0x{5:X}\n" +
                "architecture: {6}\n" +
                "OS:           {7}",
                uImage.Name,
                uImage.LoadAddress,
                uImage.Size, Misc.NormalizeBinary(uImage.Size),
                uImage.Timestamp,
                uImage.EntryPoint,
                uImage.Architecture,
                uImage.OperatingSystem
            ));
            AddFingerprint(fileName);
            UpdateLowestLoadedAddress(uImage.LoadAddress);
        }

        public IEnumerable<BinaryFingerprint> GetLoadedFingerprints()
        {
            return binaryFingerprints.ToArray();
        }

        public BinaryFingerprint GetFingerprint(ReadFilePath fileName)
        {
            return new BinaryFingerprint(fileName);
        }

        public bool TryGetAllSymbolAddresses(string symbolName, out IEnumerable<ulong> symbolAddresses, ICPU context = null)
        {
            var result = GetLookup(context).TryGetSymbolsByName(symbolName, out var symbols);
            symbolAddresses = symbols.Select(symbol => symbol.Start.RawValue);
            return result;
        }

        public IEnumerable<ulong> GetAllSymbolAddresses(string symbolName, ICPU context = null)
        {
            if(!TryGetAllSymbolAddresses(symbolName, out var symbolAddresses, context))
            {
                throw new RecoverableException(string.Format("No symbol with name `{0}` found.", symbolName));
            }
            return symbolAddresses;
        }

        public string FindSymbolAt(ulong offset, ICPU context = null)
        {
            if(!TryFindSymbolAt(offset, out var name, out var _, context))
            {
                return null;
            }
            return name;
        }

        public bool TryFindSymbolAt(ulong offset, out string name, out Symbol symbol, ICPU context = null)
        {
            if(!pcCache.TryGetValue(offset, out var entry))
            {
                if(!GetLookup(context).TryGetSymbolByAddress(offset, out symbol))
                {
                    symbol = null;
                    name = null;
                    return false;
                }
                else
                {
                    name = symbol.ToStringRelative(offset);
                }
                pcCache.Add(offset, Tuple.Create(name, symbol));
            }
            else
            {
                name = entry.Item1;
                symbol = entry.Item2;
            }

            return true;
        }

        public void MapMemory(IMappedSegment segment, IBusPeripheral owner, bool relative = true, ICPUWithMappedMemory context = null)
        {
            if(relative)
            {
                var wrappers = new List<MappedSegmentWrapper>();
                foreach(var registrationPoint in GetRegistrationPoints(owner, context))
                {
                    var wrapper = FromRegistrationPointToSegmentWrapper(segment, registrationPoint, context);
                    if(wrapper != null)
                    {
                        wrappers.Add(wrapper);
                    }
                }
                AddMappings(wrappers, owner);
            }
            else
            {
                AddMappings(new [] { new MappedSegmentWrapper(segment, 0, long.MaxValue, context) }, owner);
            }
        }

        public void UnmapMemory(Range range, ICPU context = null)
        {
            lock(cpuSync)
            {
                foreach(var cpu in GetCPUsForContext<ICPUWithMappedMemory>(context))
                {
                    mappingsRemoved = true;
                    cpu.UnmapMemory(range);
                }
            }
        }

        public void SetPageAccessViaIo(ulong address)
        {
            foreach(var cpu in cpuById.Values.OfType<ICPUWithMappedMemory>())
            {
                cpu.SetPageAccessViaIo(address);
            }
        }

        public void ClearPageAccessViaIo(ulong address)
        {
            foreach(var cpu in cpuById.Values.OfType<ICPUWithMappedMemory>())
            {
                cpu.ClearPageAccessViaIo(address);
            }
        }

        public void AddWatchpointHook(ulong address, SysbusAccessWidth width, Access access, BusHookDelegate hook)
        {
            if(!Enum.IsDefined(typeof(Access), access))
            {
                throw new RecoverableException("Undefined access value.");
            }
            if(((((int)width) & 15) != (int)width) || width == 0)
            {
                throw new RecoverableException("Undefined width value.");
            }

            var handler = new BusHookHandler(hook, width);

            var dictionariesToUpdate = new List<Dictionary<ulong, List<BusHookHandler>>>();

            if((access & Access.Read) != 0)
            {
                dictionariesToUpdate.Add(hooksOnRead);
            }
            if((access & Access.Write) != 0)
            {
                dictionariesToUpdate.Add(hooksOnWrite);
            }
            foreach(var dictionary in dictionariesToUpdate)
            {
                if(dictionary.ContainsKey(address))
                {
                    dictionary[address].Add(handler);
                }
                else
                {
                    dictionary[address] = new List<BusHookHandler> { handler };
                }
            }
            UpdatePageAccesses();
        }

        public void RemoveWatchpointHook(ulong address, BusHookDelegate hook)
        {
            foreach(var hookDictionary in new [] { hooksOnRead, hooksOnWrite })
            {
                List<BusHookHandler> handlers;
                if(hookDictionary.TryGetValue(address, out handlers))
                {
                    handlers.RemoveAll(x => x.ContainsAction(hook));
                    if(handlers.Count == 0)
                    {
                        hookDictionary.Remove(address);
                    }
                }
            }

            ClearPageAccessViaIo(address);
            UpdatePageAccesses();
        }

        public void RemoveAllWatchpointHooks(ulong address)
        {
            hooksOnRead.Remove(address);
            hooksOnWrite.Remove(address);
            ClearPageAccessViaIo(address);
            UpdatePageAccesses();
        }

        public bool TryGetWatchpointsAt(ulong address, Access access, out List<BusHookHandler> result)
        {
            if(access == Access.ReadAndWrite || access == Access.Read)
            {
                if(hooksOnRead.TryGetValue(address, out result))
                {
                    return true;
                }
                else if(access == Access.Read)
                {
                    result = null;
                    return false;
                }
            }
            return hooksOnWrite.TryGetValue(address, out result);
        }

        /// <remarks>Doesn't include peripherals registered using NullRegistrationPoints.</remarks>
        public IEnumerable<BusRangeRegistration> GetRegistrationPoints(IBusPeripheral peripheral, ICPU context = null)
        {
            return GetAccessiblePeripheralsForContext(context)
                .Where(x => x.Peripheral == peripheral)
                .Select(x => x.RegistrationPoint);
        }

        /// <remarks>Doesn't include peripherals registered using NullRegistrationPoints.</remarks>
        public IEnumerable<BusRangeRegistration> GetRegistrationPoints(IBusPeripheral peripheral)
        {
            // try to detect the CPU context based on the current thread
            TryGetCurrentCPU(out var context);
            return GetRegistrationPoints(peripheral, context);
        }

        public void ApplySVD(string path)
        {
            var svdDevice = new SVDParser(path, this);
            svdDevices.Add(svdDevice);
        }

        public void Tag(Range range, string tag, ulong defaultValue = 0, bool pausing = false)
        {
            var intersectings = tags.Where(x => x.Key.Intersects(range)).ToArray();
            if(intersectings.Length == 0)
            {
                tags.Add(range, new TagEntry { Name = tag, DefaultValue = defaultValue });
                if(pausing)
                {
                    pausingTags.Add(tag);
                }
                return;
            }
            // tag splitting
            if(intersectings.Length != 1)
            {
                throw new RecoverableException(string.Format(
                    "Currently subtag has to be completely contained in other tag. Given one intersects with tags: {0}",
                    intersectings.Select(x => x.Value.Name).Aggregate((x, y) => x + ", " + y)));
            }
            var parentRange = intersectings[0].Key;
            var parentName = intersectings[0].Value.Name;
            var parentDefaultValue = intersectings[0].Value.DefaultValue;
            var parentPausing = pausingTags.Contains(parentName);
            if(!parentRange.Contains(range))
            {
                throw new RecoverableException(string.Format(
                    "Currently subtag has to be completely contained in other tag, in this case {0}.", parentName));
            }
            RemoveTag(parentRange.StartAddress);
            var parentRangeAfterSplitSizeLeft = range.StartAddress - parentRange.StartAddress;
            if(parentRangeAfterSplitSizeLeft > 0)
            {
                Tag(new Range(parentRange.StartAddress, parentRangeAfterSplitSizeLeft), parentName, parentDefaultValue, parentPausing);
            }
            var parentRangeAfterSplitSizeRight = parentRange.EndAddress - range.EndAddress;
            if(parentRangeAfterSplitSizeRight > 0)
            {
                Tag(new Range(range.EndAddress + 1, parentRangeAfterSplitSizeRight), parentName, parentDefaultValue, parentPausing);
            }
            Tag(range, string.Format("{0}/{1}", parentName, tag), defaultValue, pausing);
        }

        public void RemoveTag(ulong address)
        {
            var tagsToRemove = tags.Where(x => x.Key.Contains(address)).ToArray();
            if(tagsToRemove.Length == 0)
            {
                throw new RecoverableException(string.Format("There is no tag at address 0x{0:X}.", address));
            }
            foreach(var tag in tagsToRemove)
            {
                tags.Remove(tag.Key);
                pausingTags.Remove(tag.Value.Name);
            }
        }

        public void SetAddressRangeLocked(Range range, bool locked, IPeripheral context = null)
        {
            lock(lockedRangesCollectionByContext)
            {
                // Check if `range` needs to be locked or unlocked at all.
                if(locked ? lockedRangesCollectionByContext[context].ContainsWholeRange(range) : !IsAddressRangeLocked(range, context))
                {
                    return;
                }

                using(Machine.ObtainPausedState(internalPause: true))
                {
                    RelockRange(range, locked, context);

                    lockedRangesCollectionByContext.WithStateCollection(context, stateMask: null, collection =>
                    {
                        if(locked)
                        {
                            collection.Add(range);
                        }
                        else
                        {
                            collection.Remove(range);
                        }
                    });
                }
            }
        }

        public void SetPeripheralEnabled(IPeripheral peripheral, bool enabled)
        {
            if(enabled)
            {
                lockedPeripherals.Remove(peripheral);
            }
            else
            {
                if(peripheral != null)
                {
                    lockedPeripherals.Add(peripheral);
                }
            }
        }

        /// <returns>True if any part of the <c>range</c> is locked for the given CPU (globally if <c>null</c> passed as <c>context</c>).</returns>
        public bool IsAddressRangeLocked(Range range, IPeripheral context = null)
        {
            // The locked range is either mapped for the CPU context, or globally (that is the reason for the OR)
            return (lockedRangesCollectionByContext.TryGetValue(context, initiatorState: null, out var collection) && collection.ContainsOverlappingRange(range))
                || lockedRangesCollectionByContext[null].ContainsOverlappingRange(range);
        }

        public bool IsPeripheralEnabled(IPeripheral peripheral)
        {
            if(lockedPeripherals.Contains(peripheral))
            {
                return false;
            }
            return true;
        }

        public void Clear()
        {
            ClearAll();
        }

        public void Reset()
        {
            LowestLoadedAddress = null;
            globalLookup = new SymbolLookup();
            localLookups = new Dictionary<ICPU, SymbolLookup>();
            pcCache.Invalidate();
        }

        public string DecorateWithCPUNameAndPC(string str)
        {
            if(!TryGetCurrentCPU(out var cpu) || !Machine.TryGetLocalName(cpu, out var cpuName))
            {
                return str;
            }

            // you probably wonder why 26?
            // * we assume at least 3 characters for cpu name
            // * 64-bit PC value nees 18 characters
            // * there are 5 more separating characters
            var builder = new StringBuilder(str.Length + 26);
            builder
                .Append("[")
                .Append(cpuName);

            builder.AppendFormat(": 0x{0:X}", cpu.PC.RawValue);

            builder
                .Append("] ")
                .Append(str);

            return builder.ToString();
        }

        public SymbolLookup GetLookup(ICPU context = null)
        {
            if(context == null
               || !localLookups.TryGetValue(context, out var cpuLookup))
            {
                return globalLookup;
            }

            return cpuLookup;
        }

        public IMachine Machine { get; }

        public int UnexpectedReads
        {
            get
            {
                return Interlocked.CompareExchange(ref unexpectedReads, 0, 0);
            }
        }

        public int UnexpectedWrites
        {
            get
            {
                return Interlocked.CompareExchange(ref unexpectedWrites, 0, 0);
            }
        }

        public ulong? LowestLoadedAddress { get; private set; }

        /// <returns>
        /// The returned <c>IEnumerable</c> always enumerates all peripherals registered globally
        /// but also peripherals registered per CPU are enumerated if called in CPU context.
        /// </returns>
        public IEnumerable<IRegistered<IBusPeripheral, BusRangeRegistration>> Children
        {
            get
            {
                foreach(var peripheral in GetPeripheralsForCurrentCPU())
                {
                    yield return peripheral;
                }
            }
        }

        public bool IsMultiCore
        {
            get
            {
                return cpuById.Count() > 1;
            }
        }

        public Endianess Endianess
        {
            get
            {
                return endianess;
            }
            set
            {
                if(peripheralRegistered)
                {
                    throw new RecoverableException("Currently one has to set endianess before any peripheral is registered.");
                }
                endianess = value;
            }
        }

        public UnhandledAccessBehaviour UnhandledAccessBehaviour { get; set; }

        public event Action<IMachine> OnSymbolsChanged;

        private SymbolLookup GetOrCreateLookup(ICPU context)
        {
            if(context == null)
            {
                return globalLookup;
            }

            if(!localLookups.TryGetValue(context, out var lookup))
            {
                lookup = new SymbolLookup();
                localLookups[context] = lookup;
            }

            return lookup;
        }

        private void RemoveLookup(ICPU context = null)
        {
            if(context == null)
            {
                globalLookup = new SymbolLookup();
            }
            else
            {
                localLookups.Remove(context);
            }
        }

        private void UnregisterInner(IBusPeripheral peripheral)
        {
            RemoveMappingsForPeripheral(peripheral);

            // remove the peripheral from all cpu-local and the global mappings
            foreach(var pair in peripheralsCollectionByContext.GetAllContextKeys()
                .SelectMany(context => peripheralsCollectionByContext.GetAllStateKeys(context).Select(stateMask => new { context, stateMask })))
            {
                peripheralsCollectionByContext.WithStateCollection(pair.context, stateMask: pair.stateMask, collection =>
                {
                    collection.Remove(peripheral);
                });
            }
            foreach(var stateMask in peripheralsCollectionByContext.GetAllStateKeys(context: null))
            {
                peripheralsCollectionByContext.WithStateCollection(context: null, stateMask, collection =>
                {
                    collection.Remove(peripheral);
                });
            }
            RemoveContextKeys(peripheral);
        }

        private void UnregisterInner(IBusRegistered<IBusPeripheral> busRegistered)
        {
            if(mappingsForPeripheral.ContainsKey(busRegistered.Peripheral))
            {
                var toRemove = new HashSet<MappedSegmentWrapper>();
                // it is assumed that mapped segment cannot be partially outside the registration point range
                foreach(var mapping in mappingsForPeripheral[busRegistered.Peripheral].Where(x => busRegistered.RegistrationPoint.Range.Contains(x.StartingOffset)))
                {
                    UnmapMemory(new Range(mapping.StartingOffset, checked((ulong)mapping.Size)));
                    toRemove.Add(mapping);
                }
                mappingsForPeripheral[busRegistered.Peripheral].RemoveAll(x => toRemove.Contains(x));
                if(mappingsForPeripheral[busRegistered.Peripheral].Count == 0)
                {
                    mappingsForPeripheral.Remove(busRegistered.Peripheral);
                }
            }
            var perCoreRegistration = busRegistered.RegistrationPoint as IBusRegistration;
            peripheralsCollectionByContext.WithStateCollection(perCoreRegistration.Initiator, perCoreRegistration.StateMask, collection =>
            {
                collection.Remove(busRegistered.RegistrationPoint.Range.StartAddress, busRegistered.RegistrationPoint.Range.EndAddress);
            });
            RemoveContextKeys(busRegistered.Peripheral);
        }

        // this wrapper is to avoid compiler crashing on Ubuntu 20.04;
        // for unknown reasons calling `TryGetCurrentCPU` in the `Children` getter
        // caused the compiler to throw na InternalErrorException/NullReferenceException
        // when building sources
        private IEnumerable<IBusRegistered<IBusPeripheral>> GetPeripheralsForCurrentCPU()
        {
            TryGetCurrentCPU(out var context);
            return GetAccessiblePeripheralsForContext(context);
        }

        /// <summary>
        /// This method will return all accessible peripherals for the given context.
        /// This means all peripherals accessible only in the current context, and peripherals accessible globally (from any - `null` - context).
        /// </summary>
        private IEnumerable<IBusRegistered<IBusPeripheral>> GetAccessiblePeripheralsForContext(IPeripheral context, ulong? initiatorState = null)
        {
            var locals = peripheralsCollectionByContext.GetValue(context, initiatorState).Peripherals;
            return context != null ? locals.Concat(peripheralsCollectionByContext[null].Peripherals) : locals;
        }

        private void FillAccessMethodsWithTaggedMethods(IBusPeripheral peripheral, string tag, ref PeripheralAccessMethods methods)
        {
            methods.Peripheral = peripheral;
            methods.Tag = tag;

            var customAccessMethods = new Dictionary<Tuple<BusAccess.Method, BusAccess.Operation>, MethodInfo>();
            bool noRegion = true;
            foreach(var method in peripheral.GetType().GetMethods())
            {
                Type signature = null;
                if(!Misc.TryGetMatchingSignature(BusAccess.Delegates, method, out signature))
                {
                    continue;
                }

                var accessGroupAttribute = (ConnectionRegionAttribute)method.GetCustomAttributes(typeof(ConnectionRegionAttribute), true).FirstOrDefault();
                if(accessGroupAttribute == null || accessGroupAttribute.Name != tag)
                {
                    continue;
                }

                var accessMethod = BusAccess.GetMethodFromSignature(signature);
                var accessOperation = BusAccess.GetOperationFromSignature(signature);

                var tuple = Tuple.Create(accessMethod, accessOperation);
                if(customAccessMethods.ContainsKey(tuple))
                {
                    throw new RegistrationException(string.Format("Only one method for operation {0} accessing {1} registers is allowed.", accessOperation, accessMethod));
                }

                customAccessMethods[tuple] = method;
                methods.SetMethod(method, peripheral, accessOperation, accessMethod);
                noRegion = false;
            }

            if(noRegion)
            {
                throw new RegistrationException($"No region \"{tag}\" is available for {peripheral}.");
            }

            foreach(var tuple in customAccessMethods)
            {
                var complementingOperation = BusAccess.GetComplementingOperation(tuple.Key.Item2);
                if(!customAccessMethods.ContainsKey(Tuple.Create(tuple.Key.Item1, complementingOperation)))
                {
                    throw new RegistrationException($"{complementingOperation}{tuple.Key.Item1} is not specified for {tag}");
                }
            }

            FillAccessMethodsWithDefaultMethods(peripheral, ref methods);
        }

        private void FillAccessMethodsWithDefaultMethods(IBusPeripheral peripheral, ref PeripheralAccessMethods methods)
        {
            methods.Peripheral = peripheral;

            var bytePeripheral = peripheral as IBytePeripheral;
            var wordPeripheral = peripheral as IWordPeripheral;
            var dwordPeripheral = peripheral as IDoubleWordPeripheral;
            var qwordPeripheral = peripheral as IQuadWordPeripheral;
            BytePeripheralWrapper byteWrapper = null;
            WordPeripheralWrapper wordWrapper = null;
            DoubleWordPeripheralWrapper dwordWrapper = null;
            QuadWordPeripheralWrapper qwordWrapper = null;

            if(methods.ReadByte != null)
            {
                byteWrapper = new BytePeripheralWrapper(methods.ReadByte, methods.WriteByte);
            }
            if(methods.ReadWord != null)
            {
                // why there are such wrappers? since device can be registered through
                // method specific registration points
                wordWrapper = new WordPeripheralWrapper(methods.ReadWord, methods.WriteWord);
            }
            if(methods.ReadDoubleWord != null)
            {
                dwordWrapper = new DoubleWordPeripheralWrapper(methods.ReadDoubleWord, methods.WriteDoubleWord);
            }
            if(methods.ReadQuadWord != null)
            {
                qwordWrapper = new QuadWordPeripheralWrapper(methods.ReadQuadWord, methods.WriteQuadWord);
            }

            if(bytePeripheral == null && wordPeripheral == null && dwordPeripheral == null && qwordPeripheral == null
                    && byteWrapper == null && wordWrapper == null && dwordWrapper == null && qwordWrapper == null)
            {
                throw new RegistrationException(string.Format("Cannot register peripheral {0}, it does not implement any of IBusPeripheral derived interfaces," +
                "nor any other methods were pointed.", peripheral));
            }

            // We need to pass in Endianess as a default because at this point the peripheral
            // is not yet associated with a machine.
            Endianess periEndianess = peripheral.GetEndianness(Endianess);
            // Note that the condition for applying ReadByteUsingDoubleWordBigEndian et al is different than the condition
            // for byte-swapping correctly-sized accesses! The former is needed for all big-endian peripherals, the
            // latter - only in the cross-endianness case. This is to ensure that on a big-endian bus, reading a byte
            // at offset 0 from a peripheral that only supports double word access and has a single register with value
            // 0x11223344 correctly returns 0x11, and not 0x44 as it would if ReadByteUsingDoubleWord were used.
            var translatedAccessNeedsSwap = Endianess == Endianess.BigEndian;
            var matchingAccessNeedsSwap = periEndianess != Endianess;

            var allowedTranslations = default(AllowedTranslation);
            var allowedTranslationsAttributes = peripheral.GetType().GetCustomAttributes(typeof(AllowedTranslationsAttribute), true);
            if(allowedTranslationsAttributes.Length != 0)
            {
                allowedTranslations = ((AllowedTranslationsAttribute)allowedTranslationsAttributes[0]).AllowedTranslations;
            }

            // If the CPU endianness does not match the bus endianness, this endianness mismatch
            // is basically an additional swap. Instead of performing it we reverse the condition.
            // This is the case on PowerPC, for example: there the translation library is always built
            // in big-endian mode, and if the CPU is running in little-endian mode, it performs byte
            // swapping separately. This is to support switching endianness at runtime, but note that
            // if this is actually done, peripheral accesses will be reversed.
            if(hasCpuWithMismatchedEndianness)
            {
                matchingAccessNeedsSwap = !matchingAccessNeedsSwap;
                translatedAccessNeedsSwap = !translatedAccessNeedsSwap;
                // Other translation types will behave incorrectly in this case.
                allowedTranslations &=
                    AllowedTranslation.ByteToWord | AllowedTranslation.ByteToDoubleWord | AllowedTranslation.ByteToQuadWord |
                    AllowedTranslation.WordToByte | AllowedTranslation.DoubleWordToByte | AllowedTranslation.QuadWordToByte;
            }

            // When methods don't have tag, it means they are regular peripheral methods (not regions).
            // Use peripheral methods for accesses.
            if(methods.Tag == null)
            {
                if(methods.ReadByte == null && bytePeripheral != null)
                {
                    methods.ReadByte = bytePeripheral.ReadByte;
                    methods.WriteByte = bytePeripheral.WriteByte;
                }
                if(methods.ReadWord == null && wordPeripheral != null)
                {
                    methods.ReadWord = matchingAccessNeedsSwap ? (BusAccess.WordReadMethod)wordPeripheral.ReadWordBigEndian : wordPeripheral.ReadWord;
                    methods.WriteWord = matchingAccessNeedsSwap ? (BusAccess.WordWriteMethod)wordPeripheral.WriteWordBigEndian : wordPeripheral.WriteWord;
                }
                if(methods.ReadDoubleWord == null && dwordPeripheral != null)
                {
                    methods.ReadDoubleWord = matchingAccessNeedsSwap ? (BusAccess.DoubleWordReadMethod)dwordPeripheral.ReadDoubleWordBigEndian : dwordPeripheral.ReadDoubleWord;
                    methods.WriteDoubleWord = matchingAccessNeedsSwap ? (BusAccess.DoubleWordWriteMethod)dwordPeripheral.WriteDoubleWordBigEndian : dwordPeripheral.WriteDoubleWord;
                }
                if(methods.ReadQuadWord == null && qwordPeripheral != null)
                {
                    methods.ReadQuadWord = matchingAccessNeedsSwap ? (BusAccess.QuadWordReadMethod)qwordPeripheral.ReadQuadWordBigEndian : qwordPeripheral.ReadQuadWord;
                    methods.WriteQuadWord = matchingAccessNeedsSwap ? (BusAccess.QuadWordWriteMethod)qwordPeripheral.WriteQuadWordBigEndian : qwordPeripheral.WriteQuadWord;
                }
            }

            if(methods.ReadByte == null) // they are null or not always in pairs
            {
                if(qwordWrapper != null && (allowedTranslations & AllowedTranslation.ByteToQuadWord) != 0)
                {
                    methods.ReadByte = translatedAccessNeedsSwap ? (BusAccess.ByteReadMethod)qwordWrapper.ReadByteUsingQuadWordBigEndian : qwordWrapper.ReadByteUsingQuadWord;
                    methods.WriteByte = translatedAccessNeedsSwap ? (BusAccess.ByteWriteMethod)qwordWrapper.WriteByteUsingQuadWordBigEndian : qwordWrapper.WriteByteUsingQuadWord;
                }
                else if(dwordWrapper != null && (allowedTranslations & AllowedTranslation.ByteToDoubleWord) != 0)
                {
                    methods.ReadByte = translatedAccessNeedsSwap ? (BusAccess.ByteReadMethod)dwordWrapper.ReadByteUsingDoubleWordBigEndian : dwordWrapper.ReadByteUsingDoubleWord;
                    methods.WriteByte = translatedAccessNeedsSwap ? (BusAccess.ByteWriteMethod)dwordWrapper.WriteByteUsingDoubleWordBigEndian : dwordWrapper.WriteByteUsingDoubleWord;
                }
                else if(wordWrapper != null && (allowedTranslations & AllowedTranslation.ByteToWord) != 0)
                {
                    methods.ReadByte = translatedAccessNeedsSwap ? (BusAccess.ByteReadMethod)wordWrapper.ReadByteUsingWordBigEndian : wordWrapper.ReadByteUsingWord;
                    methods.WriteByte = translatedAccessNeedsSwap ? (BusAccess.ByteWriteMethod)wordWrapper.WriteByteUsingWordBigEndian : wordWrapper.WriteByteUsingWord;
                }
                else if(qwordPeripheral != null && (allowedTranslations & AllowedTranslation.ByteToQuadWord) != 0)
                {
                    methods.ReadByte = translatedAccessNeedsSwap ? (BusAccess.ByteReadMethod)qwordPeripheral.ReadByteUsingQuadWordBigEndian : qwordPeripheral.ReadByteUsingQuadWord;
                    methods.WriteByte = translatedAccessNeedsSwap ? (BusAccess.ByteWriteMethod)qwordPeripheral.WriteByteUsingQuadWordBigEndian : qwordPeripheral.WriteByteUsingQuadWord;
                }
                else if(dwordPeripheral != null && (allowedTranslations & AllowedTranslation.ByteToDoubleWord) != 0)
                {
                    methods.ReadByte = translatedAccessNeedsSwap ? (BusAccess.ByteReadMethod)dwordPeripheral.ReadByteUsingDoubleWordBigEndian : dwordPeripheral.ReadByteUsingDoubleWord;
                    methods.WriteByte = translatedAccessNeedsSwap ? (BusAccess.ByteWriteMethod)dwordPeripheral.WriteByteUsingDoubleWordBigEndian : dwordPeripheral.WriteByteUsingDoubleWord;
                }
                else if(wordPeripheral != null && (allowedTranslations & AllowedTranslation.ByteToWord) != 0)
                {
                    methods.ReadByte = translatedAccessNeedsSwap ? (BusAccess.ByteReadMethod)wordPeripheral.ReadByteUsingWordBigEndian : wordPeripheral.ReadByteUsingWord;
                    methods.WriteByte = translatedAccessNeedsSwap ? (BusAccess.ByteWriteMethod)wordPeripheral.WriteByteUsingWordBigEndian : wordPeripheral.WriteByteUsingWord;
                }

                else
                {
                    methods.ReadByte = peripheral.ReadByteNotTranslated;
                    methods.WriteByte = peripheral.WriteByteNotTranslated;
                }
            }

            if(methods.ReadWord == null)
            {
                if(qwordWrapper != null && (allowedTranslations & AllowedTranslation.WordToQuadWord) != 0)
                {
                    methods.ReadWord = translatedAccessNeedsSwap ? (BusAccess.WordReadMethod)qwordWrapper.ReadWordUsingQuadWordBigEndian : qwordWrapper.ReadWordUsingQuadWord;
                    methods.WriteWord = translatedAccessNeedsSwap ? (BusAccess.WordWriteMethod)qwordWrapper.WriteWordUsingQuadWordBigEndian : qwordWrapper.WriteWordUsingQuadWord;
                }
                else if(dwordWrapper != null && (allowedTranslations & AllowedTranslation.WordToDoubleWord) != 0)
                {
                    methods.ReadWord = translatedAccessNeedsSwap ? (BusAccess.WordReadMethod)dwordWrapper.ReadWordUsingDoubleWordBigEndian : dwordWrapper.ReadWordUsingDoubleWord;
                    methods.WriteWord = translatedAccessNeedsSwap ? (BusAccess.WordWriteMethod)dwordWrapper.WriteWordUsingDoubleWordBigEndian : dwordWrapper.WriteWordUsingDoubleWord;
                }
                else if(byteWrapper != null && (allowedTranslations & AllowedTranslation.WordToByte) != 0)
                {
                    methods.ReadWord = translatedAccessNeedsSwap ? (BusAccess.WordReadMethod)byteWrapper.ReadWordUsingByteBigEndian : byteWrapper.ReadWordUsingByte;
                    methods.WriteWord = translatedAccessNeedsSwap ? (BusAccess.WordWriteMethod)byteWrapper.WriteWordUsingByteBigEndian : byteWrapper.WriteWordUsingByte;
                }
                else if(qwordPeripheral != null && (allowedTranslations & AllowedTranslation.WordToQuadWord) != 0)
                {
                    methods.ReadWord = translatedAccessNeedsSwap ? (BusAccess.WordReadMethod)qwordPeripheral.ReadWordUsingQuadWordBigEndian : qwordPeripheral.ReadWordUsingQuadWord;
                    methods.WriteWord = translatedAccessNeedsSwap ? (BusAccess.WordWriteMethod)qwordPeripheral.WriteWordUsingQuadWordBigEndian : qwordPeripheral.WriteWordUsingQuadWord;
                }
                else if(dwordPeripheral != null && (allowedTranslations & AllowedTranslation.WordToDoubleWord) != 0)
                {
                    methods.ReadWord = translatedAccessNeedsSwap ? (BusAccess.WordReadMethod)dwordPeripheral.ReadWordUsingDoubleWordBigEndian : dwordPeripheral.ReadWordUsingDoubleWord;
                    methods.WriteWord = translatedAccessNeedsSwap ? (BusAccess.WordWriteMethod)dwordPeripheral.WriteWordUsingDoubleWordBigEndian : dwordPeripheral.WriteWordUsingDoubleWord;
                }
                else if(bytePeripheral != null && (allowedTranslations & AllowedTranslation.WordToByte) != 0)
                {
                    methods.ReadWord = translatedAccessNeedsSwap ? (BusAccess.WordReadMethod)bytePeripheral.ReadWordUsingByteBigEndian : bytePeripheral.ReadWordUsingByte;
                    methods.WriteWord = translatedAccessNeedsSwap ? (BusAccess.WordWriteMethod)bytePeripheral.WriteWordUsingByteBigEndian : bytePeripheral.WriteWordUsingByte;
                }
                else
                {
                    methods.ReadWord = peripheral.ReadWordNotTranslated;
                    methods.WriteWord = peripheral.WriteWordNotTranslated;
                }
            }
            else if(matchingAccessNeedsSwap && wordWrapper != null)
            {
                methods.ReadWord = (BusAccess.WordReadMethod)wordWrapper.ReadWordBigEndian;
                methods.WriteWord = (BusAccess.WordWriteMethod)wordWrapper.WriteWordBigEndian;
            }

            if(methods.ReadDoubleWord == null)
            {
                if(qwordWrapper != null && (allowedTranslations & AllowedTranslation.DoubleWordToQuadWord) != 0)
                {
                    methods.ReadDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordReadMethod)qwordWrapper.ReadDoubleWordUsingQuadWordBigEndian : qwordWrapper.ReadDoubleWordUsingQuadWord;
                    methods.WriteDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordWriteMethod)qwordWrapper.WriteDoubleWordUsingQuadWordBigEndian : qwordWrapper.WriteDoubleWordUsingQuadWord;
                }
                else if(wordWrapper != null && (allowedTranslations & AllowedTranslation.DoubleWordToWord) != 0)
                {
                    methods.ReadDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordReadMethod)wordWrapper.ReadDoubleWordUsingWordBigEndian : wordWrapper.ReadDoubleWordUsingWord;
                    methods.WriteDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordWriteMethod)wordWrapper.WriteDoubleWordUsingWordBigEndian : wordWrapper.WriteDoubleWordUsingWord;
                }
                else if(byteWrapper != null && (allowedTranslations & AllowedTranslation.DoubleWordToByte) != 0)
                {
                    methods.ReadDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordReadMethod)byteWrapper.ReadDoubleWordUsingByteBigEndian : byteWrapper.ReadDoubleWordUsingByte;
                    methods.WriteDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordWriteMethod)byteWrapper.WriteDoubleWordUsingByteBigEndian : byteWrapper.WriteDoubleWordUsingByte;
                }
                else if(qwordPeripheral != null && (allowedTranslations & AllowedTranslation.DoubleWordToQuadWord) != 0)
                {
                    methods.ReadDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordReadMethod)qwordPeripheral.ReadDoubleWordUsingQuadWordBigEndian : qwordPeripheral.ReadDoubleWordUsingQuadWord;
                    methods.WriteDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordWriteMethod)qwordPeripheral.WriteDoubleWordUsingQuadWordBigEndian : qwordPeripheral.WriteDoubleWordUsingQuadWord;
                }
                else if(wordPeripheral != null && (allowedTranslations & AllowedTranslation.DoubleWordToWord) != 0)
                {
                    methods.ReadDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordReadMethod)wordPeripheral.ReadDoubleWordUsingWordBigEndian : wordPeripheral.ReadDoubleWordUsingWord;
                    methods.WriteDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordWriteMethod)wordPeripheral.WriteDoubleWordUsingWordBigEndian : wordPeripheral.WriteDoubleWordUsingWord;
                }
                else if(bytePeripheral != null && (allowedTranslations & AllowedTranslation.DoubleWordToByte) != 0)
                {
                    methods.ReadDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordReadMethod)bytePeripheral.ReadDoubleWordUsingByteBigEndian : bytePeripheral.ReadDoubleWordUsingByte;
                    methods.WriteDoubleWord = translatedAccessNeedsSwap ? (BusAccess.DoubleWordWriteMethod)bytePeripheral.WriteDoubleWordUsingByteBigEndian : bytePeripheral.WriteDoubleWordUsingByte;
                }
                else
                {
                    methods.ReadDoubleWord = peripheral.ReadDoubleWordNotTranslated;
                    methods.WriteDoubleWord = peripheral.WriteDoubleWordNotTranslated;
                }
            }
            else if(matchingAccessNeedsSwap && dwordWrapper != null)
            {
                methods.ReadDoubleWord = (BusAccess.DoubleWordReadMethod)dwordWrapper.ReadDoubleWordBigEndian;
                methods.WriteDoubleWord = (BusAccess.DoubleWordWriteMethod)dwordWrapper.WriteDoubleWordBigEndian;
            }
            if(methods.ReadQuadWord == null)
            {
                if(dwordWrapper != null && (allowedTranslations & AllowedTranslation.QuadWordToDoubleWord) != 0)
                {
                    methods.ReadQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordReadMethod)dwordWrapper.ReadQuadWordUsingDoubleWordBigEndian : dwordWrapper.ReadQuadWordUsingDoubleWord;
                    methods.WriteQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordWriteMethod)dwordWrapper.WriteQuadWordUsingDoubleWordBigEndian : dwordWrapper.WriteQuadWordUsingDoubleWord;
                }
                else if(wordWrapper != null && (allowedTranslations & AllowedTranslation.QuadWordToWord) != 0)
                {
                    methods.ReadQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordReadMethod)wordWrapper.ReadQuadWordUsingWordBigEndian : wordWrapper.ReadQuadWordUsingWord;
                    methods.WriteQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordWriteMethod)wordWrapper.WriteQuadWordUsingWordBigEndian : wordWrapper.WriteQuadWordUsingWord;
                }
                else if(byteWrapper != null && (allowedTranslations & AllowedTranslation.QuadWordToByte) != 0)
                {
                    methods.ReadQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordReadMethod)byteWrapper.ReadQuadWordUsingByteBigEndian : byteWrapper.ReadQuadWordUsingByte;
                    methods.WriteQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordWriteMethod)byteWrapper.WriteQuadWordUsingByteBigEndian : byteWrapper.WriteQuadWordUsingByte;
                }
                else if(dwordPeripheral != null && (allowedTranslations & AllowedTranslation.QuadWordToDoubleWord) != 0)
                {
                    methods.ReadQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordReadMethod)dwordPeripheral.ReadQuadWordUsingDoubleWordBigEndian : dwordPeripheral.ReadQuadWordUsingDoubleWord;
                    methods.WriteQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordWriteMethod)dwordPeripheral.WriteQuadWordUsingDoubleWordBigEndian : dwordPeripheral.WriteQuadWordUsingDoubleWord;
                }
                else if(wordPeripheral != null && (allowedTranslations & AllowedTranslation.QuadWordToWord) != 0)
                {
                    methods.ReadQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordReadMethod)wordPeripheral.ReadQuadWordUsingWordBigEndian : wordPeripheral.ReadQuadWordUsingWord;
                    methods.WriteQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordWriteMethod)wordPeripheral.WriteQuadWordUsingWordBigEndian : wordPeripheral.WriteQuadWordUsingWord;
                }
                else if(bytePeripheral != null && (allowedTranslations & AllowedTranslation.QuadWordToByte) != 0)
                {
                    methods.ReadQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordReadMethod)bytePeripheral.ReadQuadWordUsingByteBigEndian : bytePeripheral.ReadQuadWordUsingByte;
                    methods.WriteQuadWord = translatedAccessNeedsSwap ? (BusAccess.QuadWordWriteMethod)bytePeripheral.WriteQuadWordUsingByteBigEndian : bytePeripheral.WriteQuadWordUsingByte;
                }
                else
                {
                    methods.ReadQuadWord = peripheral.ReadQuadWordNotTranslated;
                    methods.WriteQuadWord = peripheral.WriteQuadWordNotTranslated;
                }
            }
            else if(matchingAccessNeedsSwap && qwordWrapper != null)
            {
                methods.ReadQuadWord = (BusAccess.QuadWordReadMethod)qwordWrapper.ReadQuadWordBigEndian;
                methods.WriteQuadWord = (BusAccess.QuadWordWriteMethod)qwordWrapper.WriteQuadWordBigEndian;
            }
        }

        private void UpdateAccessMethods()
        {
            foreach(var peripherals in allPeripherals)
            {
                peripherals.VisitAccessMethods(null, pam =>
                {
                    if(pam.Tag != null)
                    {
                        FillAccessMethodsWithTaggedMethods(pam.Peripheral, pam.Tag, ref pam);
                    }
                    else
                    {
                        FillAccessMethodsWithDefaultMethods(pam.Peripheral, ref pam);
                    }
                    return pam;
                });
            }
        }

        private void RegisterInner(IBusPeripheral peripheral, PeripheralAccessMethods methods, BusRangeRegistration registrationPoint, IPeripheral context)
        {
            using(Machine.ObtainPausedState(true))
            {
                // Ensure the context exists if we need one, since this peripheral might be getting registered before its context is.
                // This only applies for contexts that are not CPUs, since those are always created immediately, but it's harmless to do
                // for CPUs.
                if(context != null)
                {
                    AddContextKeys(context);
                }

                var stateMask = registrationPoint.StateMask;
                var busRegisteredInContext = peripheralsCollectionByContext.GetValue(context, stateMask?.State).Peripherals;
                var intersecting = busRegisteredInContext
                    .FirstOrDefault(x => x.RegistrationPoint.Range.Intersects(registrationPoint.Range)
                                      && x.RegistrationPoint.StateMask?.Mask == registrationPoint.StateMask?.Mask);
                if(intersecting != null)
                {
                    throw new RegistrationException($"Given address {registrationPoint.Range} for peripheral {peripheral} conflicts with address {intersecting.RegistrationPoint.Range} of peripheral {intersecting.Peripheral}", "address");
                }

                var registeredPeripheral = new BusRegistered<IBusPeripheral>(peripheral, registrationPoint);

                if(IsAddressRangeLocked(registrationPoint.Range, context))
                {
                    // If it's impossible to re-lock the range, the peripheral can't be registered
                    if(!CanRangeBeLocked(registrationPoint.Range, context, out var _, out var __))
                    {
                        throw new RegistrationException($"Cannot register peripheral {peripheral} on locked range {registrationPoint.Range}");
                    }
                }

                // we also have to put missing methods
                var absoluteAddressAware = peripheral as IAbsoluteAddressAware;
                if(absoluteAddressAware != null)
                {
                    methods.SetAbsoluteAddress = absoluteAddressAware.SetAbsoluteAddress;
                }
                peripheralsCollectionByContext.WithStateCollection(context, stateMask, collection =>
                {
                    // Currently the end address is actually "one past the end address".
                    collection.Add(registrationPoint.Range.StartAddress, registrationPoint.Range.EndAddress + 1, registeredPeripheral, methods);
                });
                // let's add new mappings
                AddMappingsForPeripheral(peripheral, registrationPoint, context);
                // After adding new mappings, if the address range is locked, the mappings possibly have to be modified/unmapped on the CPU's side
                // RelockRange to make this happen
                if(IsAddressRangeLocked(registrationPoint.Range, context))
                {
                    // We've checked before if the range can be locked, so this should succeed
                    RelockRange(registrationPoint.Range, true, context);
                }
                Machine.RegisterAsAChildOf(this, peripheral, registrationPoint);
                Machine.RegisterBusController(peripheral, this);
            }

            peripheralRegistered = true;
        }

        /// <summary>
        /// This method can be used to re-trigger locking/unlocking actions on a range which is already registered as locked.
        /// This is useful when adding or relocating peripherals to the locked range.
        /// <summary>
        /// <remarks>
        /// Locking should almost always be done by calling <see cref="SetAddressRangeLocked"/>
        /// since this method doesn't update locked ranges and so should be used with caution.
        /// </remarks>
        private void RelockRange(Range range, bool locked, IPeripheral context)
        {
            using(Machine.ObtainPausedState(internalPause: true))
            {
                var cpusWithMappedMemory = idByCpu.Keys.OfType<ICPUWithMappedMemory>();
                if(cpusWithMappedMemory.Any())
                {
                    if(!CanRangeBeLocked(range, context, out var mappedInRange, out var onlyPartiallyInRange))
                    {
                        throw new RecoverableException(
                            $"Mapped peripherals registered at the given range {range} have to be fully included:\n"
                            + $"* {string.Join("\n* ", onlyPartiallyInRange)}"
                        );
                    }

                    foreach(var busRegistered in mappedInRange)
                    {
                        var registrationContext = busRegistered.RegistrationPoint.Initiator;
                        var registrationRange = busRegistered.RegistrationPoint.Range;
                        foreach(var cpu in GetCPUsForContext<ICPUWithMappedMemory>(registrationContext))
                        {
                            // There's no need to remove mappings from `mappingsForPeripheral`.
                            // They're only used when a new ICPUWithMappedMemory gets registered
                            // which isn't possible after `mappingsRemoved` is set in `UnmapMemory`.
                            cpu.SetMappedMemoryEnabled(registrationRange, enabled: !locked);
                        }
                    }
                }
            }
        }

        private bool CanRangeBeLocked(Range range, IPeripheral context, out IEnumerable<IBusRegistered<IMapped>> mappedInRange, out IEnumerable<IBusRegistered<IMapped>> onlyPartiallyInRange)
        {
            mappedInRange = GetMappedPeripherals(context).Where(x => x.RegistrationPoint.Range.Intersects(range));
            // Only allow including whole registration range of IMapped peripherals.
            onlyPartiallyInRange = mappedInRange.Where(x => !range.Contains(x.RegistrationPoint.Range));
            return !onlyPartiallyInRange.Any();
        }

        private IEnumerable<PeripheralLookupResult> FindTargets(ulong address, ulong count, IPeripheral context = null)
        {
            var result = new List<PeripheralLookupResult>();
            var written = 0UL;
            while(written < count)
            {
                var currentPosition = address + written;
                // what peripheral is at the current write position?
                var what = WhatIsAt(currentPosition, context);
                if(what == null)
                {
                    var holeStart = currentPosition;
                    // we can omit part of the array
                    // but how much?
                    var nextPeripheral = GetAccessiblePeripheralsForContext(context).OrderBy(x => x.RegistrationPoint.Range.StartAddress).FirstOrDefault(x => x.RegistrationPoint.Range.StartAddress > currentPosition);
                    if(nextPeripheral == null)
                    {
                        // hole reaches the end of the required range
                        written = count;
                    }
                    else
                    {
                        written += Math.Min(nextPeripheral.RegistrationPoint.Range.StartAddress - currentPosition, count - written);
                    }
                    var holeSize = address + written - currentPosition;
                    this.Log(LogLevel.Warning, "Tried to access bytes at non-existing peripheral in range {0}.", new Range(holeStart, holeSize));
                    continue;
                }
                var toWrite = Math.Min(count - written, what.RegistrationPoint.Range.EndAddress - currentPosition + 1);
                var singleResult = new PeripheralLookupResult();
                singleResult.What = what;
                singleResult.SourceIndex = written;
                singleResult.SourceLength = toWrite;
                singleResult.Offset = currentPosition;
                written += toWrite;
                result.Add(singleResult);
            }

            return result;
        }

        private static void ThrowIfNotAllMemory(IEnumerable<PeripheralLookupResult> targets)
        {
            foreach(var target in targets)
            {
                var iMemory = target.What.Peripheral as IMemory;
                var redirector = target.What.Peripheral as Redirector;
                if(iMemory == null && redirector == null)
                {
                    throw new RecoverableException(String.Format("Tried to access {0} but only memory accesses were allowed.", target.What.Peripheral));
                }
            }
        }

        private void UpdatePageAccesses()
        {
            foreach(var address in hooksOnRead.Select(x => x.Key).Union(hooksOnWrite.Select(x => x.Key)))
            {
                SetPageAccessViaIo(address);
            }
        }

        private void ClearAll()
        {
            lock(cpuSync)
            {
                foreach(var group in Machine.PeripheralsGroups.ActiveGroups)
                {
                    group.Unregister();
                }

                foreach(var p in allPeripherals.SelectMany(x => x.Peripherals).Select(x => x.Peripheral).Distinct().Union(GetCPUs().Cast<IPeripheral>()).ToList())
                {
                    Machine.UnregisterFromParent(p);
                }

                mappingsRemoved = false;
                InitStructures();
            }
        }

        private void UpdateLowestLoadedAddress(ulong lowestLoadedAddress)
        {
            if(!LowestLoadedAddress.HasValue)
            {
                LowestLoadedAddress = lowestLoadedAddress;
                return;
            }
            LowestLoadedAddress = Math.Min(LowestLoadedAddress.Value, lowestLoadedAddress);
        }

        private void AddFingerprint(string fileName)
        {
            binaryFingerprints.Add(new BinaryFingerprint(fileName));
        }

        private void InitStructures()
        {
            cpuById.Clear();
            idByCpu.Clear();
            hooksOnRead.Clear();
            hooksOnWrite.Clear();
            pcCache.Invalidate();
            globalLookup = new SymbolLookup();
            localLookups = new Dictionary<ICPU, SymbolLookup>();
            cachedCpuId = new ThreadLocal<int>();
            peripheralsCollectionByContext = new ContextKeyDictionary<PeripheralCollection, IReadOnlyPeripheralCollection>(() => new PeripheralCollection(this));
            lockedPeripherals = new HashSet<IPeripheral>();
            lockedRangesCollectionByContext = new ContextKeyDictionary<MinimalRangesCollection, IReadOnlyMinimalRangesCollection>(() => new MinimalRangesCollection());
            mappingsForPeripheral = new Dictionary<IBusPeripheral, List<MappedSegmentWrapper>>();
            tags = new Dictionary<Range, TagEntry>();
            svdDevices = new List<SVDParser>();
            pausingTags = new HashSet<string>();
            PostDeserializationInitStructures();
        }

        private List<MappedMemory> ObtainMemoryList()
        {
            return allPeripherals.SelectMany(x => x.Peripherals).Where(x => x.Peripheral is MappedMemory).OrderBy(x => x.RegistrationPoint.Range.StartAddress).
                Select(x => x.Peripheral).Cast<MappedMemory>().Distinct().ToList();
        }

        private void AddMappings(IEnumerable<MappedSegmentWrapper> newMappings, IBusPeripheral owner)
        {
            using(Machine.ObtainPausedState(true))
            {
                lock(cpuSync)
                {
                    var mappingsList = newMappings.ToList();
                    if(mappingsForPeripheral.ContainsKey(owner))
                    {
                        mappingsForPeripheral[owner].AddRange(newMappings);
                    }
                    else
                    {
                        mappingsForPeripheral[owner] = mappingsList;
                    }
                    // Old mappings are given to the CPU in the moment of its registration.
                    foreach(var mapping in mappingsList)
                    {
                        foreach(var cpu in GetCPUsForContext<ICPUWithMappedMemory>(mapping.Context))
                        {
                            cpu.MapMemory(mapping);
                        }
                    }
                }
            }
        }

        private void AddMappingsForPeripheral(IBusPeripheral peripheral, BusRangeRegistration registrationPoint, IPeripheral context)
        {
            var mappedPeripheral = peripheral as IMapped;
            if(mappedPeripheral == null) // The context can be null to map it globally
            {
                return;
            }
            var cpuWithMappedMemory = context as ICPUWithMappedMemory;
            var segments = mappedPeripheral.MappedSegments;
            var mappings = segments.Select(x => FromRegistrationPointToSegmentWrapper(x, registrationPoint, cpuWithMappedMemory)).Where(x => x != null);
            AddMappings(mappings, mappedPeripheral);
        }

        private void UnregisterAccessFlags(BusRangeRegistration registrationPoint, ICPU context)
        {
            foreach(var cpu in GetCPUsForContext<ICPUWithMappedMemory>(context))
            {
                var range = registrationPoint.Range;
                cpu.RegisterAccessFlags(range.StartAddress, range.Size);
            }
        }

        private bool RemoveMappingsForPeripheral(IBusPeripheral peripheral)
        {
            if(!mappingsForPeripheral.ContainsKey(peripheral))
            {
                return false;
            }
            foreach(var mapping in mappingsForPeripheral[peripheral])
            {
                UnmapMemory(new Range(mapping.StartingOffset, mapping.Size));
            }
            mappingsForPeripheral.Remove(peripheral);
            return true;
        }

        private string TryGetTag(ulong address, out ulong defaultValue)
        {
            // The `return` inside is intentional; we just want to find the first tag.
            // `FirstOrDefault` isn't used cause the default `Range` is a valid `<0, 0>` range.
            // `Any` + `First` aren't used to avoid analyzing `tags` keys up to the matching one twice.
            // `ToArray` isn't used to avoid analyzing all `tags` keys since we only use the first one.
            foreach(var tag in tags.Where(x => x.Key.Contains(address)).Select(x => x.Value))
            {
                defaultValue = tag.DefaultValue;
                return tag.Name;
            }
            defaultValue = default(ulong);
            return null;
        }

        private string EnterTag(string str, ulong address, out bool tagEntered, out ulong defaultValue)
        {
            // TODO: also pausing here in a bit hacky way
            var tag = TryGetTag(address, out defaultValue);
            if(tag == null)
            {
                tagEntered = false;
                return str;
            }
            tagEntered = true;
            if(pausingTags.Contains(tag))
            {
                Machine.Pause();
            }
            return string.Format("(tag: '{0}') {1}", tag, str);
        }

        private ulong ReportNonExistingRead(ulong address, SysbusAccessWidth type)
        {
            Interlocked.Increment(ref unexpectedReads);
            bool tagged;
            ulong defaultValue;
            var warning = EnterTag(NonExistingRead, address, out tagged, out defaultValue);
            warning = DecorateWithCPUNameAndPC(warning);
            if(UnhandledAccessBehaviour == UnhandledAccessBehaviour.DoNotReport)
            {
                return defaultValue;
            }
            if((UnhandledAccessBehaviour == UnhandledAccessBehaviour.ReportIfTagged && !tagged)
                || (UnhandledAccessBehaviour == UnhandledAccessBehaviour.ReportIfNotTagged && tagged))
            {
                return defaultValue;
            }
            if(tagged)
            {
                //strange parsing of default value ensures we get the right width, depending on the access type
                this.Log(LogLevel.Warning, warning.TrimEnd('.') + ", returning 0x{2}.", address, type, defaultValue.ToString("X16").Substring(16 - (int)type * 2));
            }
            else
            {
                ulong value;
                foreach(var svdDevice in svdDevices)
                {
                    if(svdDevice.TryReadAccess(address, out value, type))
                    {
                        return value;
                    }
                }
                this.Log(LogLevel.Warning, warning, address, type);
            }
            return defaultValue;
        }

        private void ReportNonExistingWrite(ulong address, ulong value, SysbusAccessWidth type)
        {
            Interlocked.Increment(ref unexpectedWrites);
            if(UnhandledAccessBehaviour == UnhandledAccessBehaviour.DoNotReport)
            {
                return;
            }
            bool tagged;
            var warning = EnterTag(NonExistingWrite, address, out tagged, out var _);
            warning = DecorateWithCPUNameAndPC(warning);
            if((UnhandledAccessBehaviour == UnhandledAccessBehaviour.ReportIfTagged && !tagged)
                || (UnhandledAccessBehaviour == UnhandledAccessBehaviour.ReportIfNotTagged && tagged))
            {
                return;
            }
            foreach(var svdDevice in svdDevices)
            {
                if(svdDevice.TryWriteAccess(address, value, type))
                {
                    return;
                }
            }
            this.Log(LogLevel.Warning, warning, address, value, type);
        }

        private IDisposable SetLocalContext(IPeripheral context, ulong? initiatorState = null)
        {
            return threadLocalContext.Initialize(context, initiatorState);
        }

        private void AddContextKeys(IPeripheral peripheral)
        {
            peripheralsCollectionByContext.AddContextKey(peripheral);
            lockedRangesCollectionByContext.AddContextKey(peripheral);
        }

        private void RemoveContextKeys(IPeripheral peripheral)
        {
            peripheralsCollectionByContext.RemoveContextKey(peripheral);
            lockedRangesCollectionByContext.RemoveContextKey(peripheral);
        }

        [PostDeserialization]
        private void PostDeserializationInitStructures()
        {
            threadLocalContext = new ThreadLocalContext(this);
        }

        private static MappedSegmentWrapper FromRegistrationPointToSegmentWrapper(IMappedSegment segment, BusRangeRegistration registrationPoint, ICPUWithMappedMemory context)
        {
            if(segment.StartingOffset >= registrationPoint.Range.Size + registrationPoint.Offset)
            {
                return null;
            }

            var desiredSize = Math.Min(segment.Size, registrationPoint.Range.Size + registrationPoint.Offset - segment.StartingOffset);
            return new MappedSegmentWrapper(segment, registrationPoint.Range.StartAddress - registrationPoint.Offset, desiredSize, context);
        }

        private IEnumerable<PeripheralCollection> allPeripherals => peripheralsCollectionByContext.GetAllDistinctValues();

        private ISet<IPeripheral> lockedPeripherals;

        private ContextKeyDictionary<PeripheralCollection, IReadOnlyPeripheralCollection> peripheralsCollectionByContext;
        private ContextKeyDictionary<MinimalRangesCollection, IReadOnlyMinimalRangesCollection> lockedRangesCollectionByContext;

        // It doesn't implement IDictionary because serialization doesn't work correctly for dictionaries without two generic parameters.
        private class ContextKeyDictionary<TValue, TReadOnlyValue> where TValue : TReadOnlyValue, ICoalescable<TValue> where TReadOnlyValue : class
        {
            public ContextKeyDictionary(Func<TValue> defaultFactory)
            {
                this.defaultFactory = defaultFactory;
                globalAllAccess = globalValue[StateMask.AllAccess] = defaultFactory();
            }

            // Adding the context key might happen on peripheral registration, or on first use.
            public void AddContextKey(IPeripheral key)
            {
                if(key == null)
                {
                    throw new ArgumentNullException(nameof(key));
                }
                if(cpuLocalValues.ContainsKey(key))
                {
                    return;
                }
                cpuLocalValues[key] = new Dictionary<StateMask, TValue>();
                cpuAllAccess[key] = cpuLocalValues[key][StateMask.AllAccess] = defaultFactory();
            }

            public void RemoveContextKey(IPeripheral key)
            {
                if(key == null)
                {
                    throw new ArgumentNullException(nameof(key));
                }
                cpuLocalValues.Remove(key);
                DropCaches(); // has the effect of dropping caches when a peripheral is unregistered
            }

            public TReadOnlyValue this[IPeripheral key] => GetValue(key);

            public TReadOnlyValue GetValue(IPeripheral key, ulong? initiatorState = null)
            {
                if(!TryGetValue(key, initiatorState, out var value))
                {
                    throw new RecoverableException($"{typeof(TValue).Name} not found for the given context: {key.GetName()} in state: {initiatorState}");
                }
                return value;
            }

            // Perform a mutation on the value collection for a specific initiator state and mask pair (for example to add a new peripheral)
            public void WithStateCollection(IPeripheral context, StateMask? stateMask, Action<TValue> action)
            {
                var collection = context == null ? globalValue : cpuLocalValues[context];
                var effectiveMask = stateMask ?? StateMask.AllAccess;
                if(!collection.ContainsKey(effectiveMask))
                {
                    collection[effectiveMask] = defaultFactory();
                }
                action(collection[effectiveMask]);
                DropCaches();
            }

            public IEnumerable<TValue> GetAllDistinctValues()
            {
                return cpuLocalValues.Values.SelectMany(v => v.Values).Concat(globalValue.Values).Distinct();
            }

            public IEnumerable<IPeripheral> GetAllContextKeys()
            {
                return cpuLocalValues.Keys;
            }

            public IEnumerable<StateMask> GetAllStateKeys(IPeripheral context)
            {
                return (context == null ? globalValue : cpuLocalValues[context]).Keys;
            }

            public bool TryGetValue(IPeripheral key, ulong? initiatorState, out TValue value)
            {
                if(!initiatorState.HasValue)
                {
                    if(key == null)
                    {
                        value = globalAllAccess;
                        return true;
                    }
                    // Handle reads initiated by peripherals that are never used as a context and thus have no collections.
                    // Then this will fail and it's up to the caller to fall back to the global collection.
                    return cpuAllAccess.TryGetValue(key, out value);
                }
                if(key != null && !cpuInStateCache.ContainsKey(key))
                {
                    cpuInStateCache[key] = new Dictionary<ulong, TValue>();
                }
                var cache = key == null ? globalCache : cpuInStateCache[key];
                if(cache.TryGetValue(initiatorState.Value, out var cachedValue))
                {
                    value = cachedValue;
                    return true;
                }
                else
                {
                    cache[initiatorState.Value] = cachedValue = defaultFactory();
                    return TryGetValueForState(cachedValue, key, initiatorState, out value);
                }
            }

            private bool TryGetValueForState(TValue cachedValue, IPeripheral key, ulong? initiatorState, out TValue value)
            {
                // The core of the state filtering logic. Look up which elements fit the current initiator state.
                // Then join all found state-specific collections of elements into the cached one for this state.
                var collectionToSearch = globalValue.AsEnumerable();
                if(key != null && cpuLocalValues.TryGetValue(key, out var thisCpuValues))
                {
                    // Note that in order for the 'local peripheral overrides the global one' behavior to work as intended,
                    // we must check the local peripherals first. That way they 'reserve' their spot in the cache. This function
                    // also checks the global collection when called with a context argument, but it does it only after going
                    // through the context-specific one to ensure this.
                    collectionToSearch = thisCpuValues.Concat(collectionToSearch);
                }
                bool anyHit = false;
                foreach(var pair in collectionToSearch)
                {
                    var stateMask = pair.Key;
                    if((initiatorState.Value & stateMask.Mask) == stateMask.State)
                    {
                        anyHit = true;
                        /// <see cref="PeripheralCollection.Coalesce"> doesn't add overlapping peripherals. This means that for the 'local peripheral
                        /// overrides the global one' behavior to work as intended we must check the local peripherals first, as we did above.
                        cachedValue.Coalesce(pair.Value);
                    }
                }
                value = anyHit ? cachedValue : default(TValue);
                return anyHit;
            }

            private void DropCaches()
            {
                cpuInStateCache.Clear();
                globalCache.Clear();
            }

            private readonly Dictionary<IPeripheral, Dictionary<StateMask, TValue>> cpuLocalValues = new Dictionary<IPeripheral, Dictionary<StateMask, TValue>>();
            private readonly Dictionary<IPeripheral, Dictionary<ulong, TValue>> cpuInStateCache = new Dictionary<IPeripheral, Dictionary<ulong, TValue>>();
            private readonly Func<TValue> defaultFactory;
            private readonly Dictionary<StateMask, TValue> globalValue = new Dictionary<StateMask, TValue>();
            private readonly Dictionary<ulong, TValue> globalCache = new Dictionary<ulong, TValue>();
            // Please take performance into account before removing these caches (they were added because looking up a value
            // in a Dictionary<StateMask, TValue> was very slow)
            private readonly Dictionary<IPeripheral, TValue> cpuAllAccess = new Dictionary<IPeripheral, TValue>();
            private readonly TValue globalAllAccess;
        }

        private Dictionary<IBusPeripheral, List<MappedSegmentWrapper>> mappingsForPeripheral;
        private bool mappingsRemoved;
        private bool peripheralRegistered;
        private Endianess endianess;
        private bool hasCpuWithMismatchedEndianness;
        private readonly Dictionary<ICPU, int> idByCpu;
        private readonly Dictionary<int, ICPU> cpuById;
        private readonly Dictionary<ulong, List<BusHookHandler>> hooksOnRead;
        private readonly Dictionary<ulong, List<BusHookHandler>> hooksOnWrite;

        [Constructor]
        private ThreadLocal<int> cachedCpuId;
        [Transient]
        private ThreadLocalContext threadLocalContext;
        private object cpuSync;
        private SymbolLookup globalLookup;
        private Dictionary<ICPU, SymbolLookup> localLookups;
        private Dictionary<Range, TagEntry> tags;
        private List<SVDParser> svdDevices;
        private HashSet<string> pausingTags;
        private readonly List<BinaryFingerprint> binaryFingerprints;
        private const string NonExistingRead = "Read{1} from non existing peripheral at 0x{0:X}.";
        private const string NonExistingWrite = "Write{2} to non existing peripheral at 0x{0:X}, value 0x{1:X}.";
        private const string IOExceptionMessage = "I/O error while loading ELF: {0}.";
        private const string CantFindCpuIdMessage = "Can't verify current CPU in the given context.";

        private int unexpectedReads;
        private int unexpectedWrites;

        private LRUCache<ulong, Tuple<string, Symbol>> pcCache = new LRUCache<ulong, Tuple<string, Symbol>>(10000);

        public class MappedSegmentWrapper : IMappedSegment
        {
            public MappedSegmentWrapper(IMappedSegment wrappedSegment, ulong peripheralOffset, ulong maximumSize, ICPUWithMappedMemory context)
            {
                this.wrappedSegment = wrappedSegment;
                this.peripheralOffset = peripheralOffset;
                usedSize = Math.Min(maximumSize, wrappedSegment.Size);
                this.context = context;
            }

            public void Touch()
            {
                wrappedSegment.Touch();
            }

            public override string ToString()
            {
                return string.Format("[MappedSegmentWrapper: StartingOffset=0x{0:X}, Size=0x{1:X}, OriginalStartingOffset=0x{2:X}, PeripheralOffset=0x{3:X}, Context={4}]",
                    StartingOffset, Size, OriginalStartingOffset, PeripheralOffset, context);
            }

            public ICPUWithMappedMemory Context
            {
                get
                {
                    return context;
                }
            }

            public ulong StartingOffset
            {
                get
                {
                    return peripheralOffset + wrappedSegment.StartingOffset;
                }
            }

            public ulong Size
            {
                get
                {
                    return usedSize;
                }
            }

            public IntPtr Pointer
            {
                get
                {
                    return wrappedSegment.Pointer;
                }
            }

            public ulong OriginalStartingOffset
            {
                get
                {
                    return wrappedSegment.StartingOffset;
                }
            }

            public ulong PeripheralOffset
            {
                get
                {
                    return peripheralOffset;
                }
            }

            public override bool Equals(object obj)
            {
                var objAsMappedSegmentWrapper = obj as MappedSegmentWrapper;
                if(objAsMappedSegmentWrapper == null)
                {
                    return false;
                }

                return wrappedSegment.Equals(objAsMappedSegmentWrapper.wrappedSegment)
                    && peripheralOffset == objAsMappedSegmentWrapper.peripheralOffset
                    && usedSize == objAsMappedSegmentWrapper.usedSize;
            }

            public override int GetHashCode()
            {
                unchecked
                {
                    var hash = 17;
                    hash = hash * 23 + wrappedSegment.GetHashCode();
                    hash = hash * 23 + (int)peripheralOffset;
                    hash = hash * 23 + (int)usedSize;
                    return hash;
                }
            }

            private readonly IMappedSegment wrappedSegment;
            private readonly ulong peripheralOffset;
            private readonly ulong usedSize;
            private readonly ICPUWithMappedMemory context;
        }

        private struct PeripheralLookupResult
        {
            public IBusRegistered<IBusPeripheral> What;
            public ulong Offset;
            public ulong SourceIndex;
            public ulong SourceLength;
        }

        private struct TagEntry
        {
            public string Name;
            public ulong DefaultValue;
        }

        private class ThreadLocalContext : IDisposable
        {
            public ThreadLocalContext(IBusController parent)
            {
                context = new ThreadLocal<Tuple<IPeripheral, ulong?>>(() => null, true);
                emptyDisposable.Disable();
            }

            public IDisposable Initialize(IPeripheral cpu, ulong? initiatorState)
            {
                if(cpu == null)
                {
                    return emptyDisposable;
                }
                var previousContext = context.Value;
                context.Value = Tuple.Create(cpu, initiatorState);
                return DisposableWrapper.New(() =>
                {
                    context.Value = previousContext;
                });
            }

            public void Dispose()
            {
                context.Dispose();
            }

            public bool InUse => context.Value != null;
            public IPeripheral Initiator => context.Value.Item1;
            public ulong? InitiatorState => context.Value.Item2;

            private readonly ThreadLocal<Tuple<IPeripheral, ulong?>> context;

            private static readonly DisposableWrapper emptyDisposable = new DisposableWrapper();
        }
    }
}