/* This file is part of the dynarmic project.
 * Copyright (c) 2016 MerryMage
 * SPDX-License-Identifier: 0BSD
 */

#pragma once

#include <array>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>

#include "dynarmic/frontend/A32/translate/translate_callbacks.h"
#include "dynarmic/interface/A32/arch_version.h"
#include "dynarmic/interface/optimization_flags.h"

namespace Dynarmic {
class ExclusiveMonitor;
}  // namespace Dynarmic

namespace Dynarmic {
namespace A32 {

using VAddr = std::uint32_t;

class Coprocessor;

enum class Exception {
    /// An UndefinedFault occured due to executing instruction with an unallocated encoding
    UndefinedInstruction,
    /// An unpredictable instruction is to be executed. Implementation-defined behaviour should now happen.
    /// This behaviour is up to the user of this library to define.
    UnpredictableInstruction,
    /// A decode error occurred when decoding this instruction. This should never happen.
    DecodeError,
    /// A SEV instruction was executed. The event register of all PEs should be set. (Hint instruction.)
    SendEvent,
    /// A SEVL instruction was executed. The event register of the current PE should be set. (Hint instruction.)
    SendEventLocal,
    /// A WFI instruction was executed. You may now enter a low-power state. (Hint instruction.)
    WaitForInterrupt,
    /// A WFE instruction was executed. You may now enter a low-power state if the event register is clear. (Hint instruction.)
    WaitForEvent,
    /// A YIELD instruction was executed. (Hint instruction.)
    Yield,
    /// A BKPT instruction was executed.
    Breakpoint,
    /// A PLD instruction was executed. (Hint instruction.)
    PreloadData,
    /// A PLDW instruction was executed. (Hint instruction.)
    PreloadDataWithIntentToWrite,
    /// A PLI instruction was executed. (Hint instruction.)
    PreloadInstruction,
    /// Attempted to execute a code block at an address for which MemoryReadCode returned std::nullopt.
    /// (Intended to be used to emulate memory protection faults.)
    NoExecuteFault,
};

/// These function pointers may be inserted into compiled code.
struct UserCallbacks : public TranslateCallbacks {
    virtual ~UserCallbacks() = default;

    // All reads through this callback are 4-byte aligned.
    // Memory must be interpreted as little endian.
    std::optional<std::uint32_t> MemoryReadCode(VAddr vaddr) override { return MemoryRead32(vaddr); }

    // This function is called before the instruction at pc is read.
    // IR code can be emitted by the callee prior to instruction handling.
    // By returning true the callee precludes the translation of the instruction;
    // in such case the callee is responsible for setting the terminal.
    bool PreCodeReadHook(bool /*is_thumb*/, VAddr /*pc*/, A32::IREmitter& /*ir*/) override { return true; }

    // Thus function is called before the instruction at pc is interpreted.
    // IR code can be emitted by the callee prior to translation of the instruction.
    void PreCodeTranslationHook(bool /*is_thumb*/, VAddr /*pc*/, A32::IREmitter& /*ir*/) override {}

    // Reads through these callbacks may not be aligned.
    // Memory must be interpreted as if ENDIANSTATE == 0, endianness will be corrected by the JIT.
    virtual std::uint8_t MemoryRead8(VAddr vaddr) = 0;
    virtual std::uint16_t MemoryRead16(VAddr vaddr) = 0;
    virtual std::uint32_t MemoryRead32(VAddr vaddr) = 0;
    virtual std::uint64_t MemoryRead64(VAddr vaddr) = 0;

    // Writes through these callbacks may not be aligned.
    virtual void MemoryWrite8(VAddr vaddr, std::uint8_t value) = 0;
    virtual void MemoryWrite16(VAddr vaddr, std::uint16_t value) = 0;
    virtual void MemoryWrite32(VAddr vaddr, std::uint32_t value) = 0;
    virtual void MemoryWrite64(VAddr vaddr, std::uint64_t value) = 0;

    // Writes through these callbacks may not be aligned.
    virtual bool MemoryWriteExclusive8(VAddr /*vaddr*/, std::uint8_t /*value*/, std::uint8_t /*expected*/) { return false; }
    virtual bool MemoryWriteExclusive16(VAddr /*vaddr*/, std::uint16_t /*value*/, std::uint16_t /*expected*/) { return false; }
    virtual bool MemoryWriteExclusive32(VAddr /*vaddr*/, std::uint32_t /*value*/, std::uint32_t /*expected*/) { return false; }
    virtual bool MemoryWriteExclusive64(VAddr /*vaddr*/, std::uint64_t /*value*/, std::uint64_t /*expected*/) { return false; }

    // If this callback returns true, the JIT will assume MemoryRead* callbacks will always
    // return the same value at any point in time for this vaddr. The JIT may use this information
    // in optimizations.
    // A conservative implementation that always returns false is safe.
    virtual bool IsReadOnlyMemory(VAddr /*vaddr*/) { return false; }

    /// The interpreter must execute exactly num_instructions starting from PC.
    virtual void InterpreterFallback(VAddr pc, size_t num_instructions) = 0;

    // This callback is called whenever a SVC instruction is executed.
    virtual void CallSVC(std::uint32_t swi) = 0;

    virtual void ExceptionRaised(VAddr pc, Exception exception) = 0;

    virtual void InstructionSynchronizationBarrierRaised() {}

    // Timing-related callbacks
    // ticks ticks have passed
    virtual void AddTicks(std::uint64_t ticks) = 0;
    // How many more ticks am I allowed to execute?
    virtual std::uint64_t GetTicksRemaining() = 0;
    // How many ticks should this instruction take to execute?
    std::uint64_t GetTicksForCode(bool /*is_thumb*/, VAddr /*vaddr*/, std::uint32_t /*instruction*/) override { return 1; }
};

struct UserConfig {
    UserCallbacks* callbacks;

    size_t processor_id = 0;
    ExclusiveMonitor* global_monitor = nullptr;

    /// Select the architecture version to use.
    /// There are minor behavioural differences between versions.
    ArchVersion arch_version = ArchVersion::v8;

    /// This selects other optimizations than can't otherwise be disabled by setting other
    /// configuration options. This includes:
    /// - IR optimizations
    /// - Block linking optimizations
    /// - RSB optimizations
    /// This is intended to be used for debugging.
    OptimizationFlag optimizations = all_safe_optimizations;

    bool HasOptimization(OptimizationFlag f) const {
        if (!unsafe_optimizations) {
            f &= all_safe_optimizations;
        }
        return (f & optimizations) != no_optimizations;
    }

    /// This enables unsafe optimizations that reduce emulation accuracy in favour of speed.
    /// For safety, in order to enable unsafe optimizations you have to set BOTH this flag
    /// AND the appropriate flag bits above.
    /// The prefered and tested mode for this library is with unsafe optimizations disabled.
    bool unsafe_optimizations = false;

    // Page Table
    // The page table is used for faster memory access. If an entry in the table is nullptr,
    // the JIT will fallback to calling the MemoryRead*/MemoryWrite* callbacks.
    static constexpr std::size_t PAGE_BITS = 12;
    static constexpr std::size_t NUM_PAGE_TABLE_ENTRIES = 1 << (32 - PAGE_BITS);
    std::array<std::uint8_t*, NUM_PAGE_TABLE_ENTRIES>* page_table = nullptr;
    /// Determines if the pointer in the page_table shall be offseted locally or globally.
    /// 'false' will access page_table[addr >> bits][addr & mask]
    /// 'true'  will access page_table[addr >> bits][addr]
    /// Note: page_table[addr >> bits] will still be checked to verify active pages.
    ///       So there might be wrongly faulted pages which maps to nullptr.
    ///       This can be avoided by carefully allocating the memory region.
    bool absolute_offset_page_table = false;
    /// Masks out the first N bits in host pointers from the page table.
    /// The intention behind this is to allow users of Dynarmic to pack attributes in the
    /// same integer and update the pointer attribute pair atomically.
    /// If the configured value is 3, all pointers will be forcefully aligned to 8 bytes.
    int page_table_pointer_mask_bits = 0;
    /// Determines if we should detect memory accesses via page_table that straddle are
    /// misaligned. Accesses that straddle page boundaries will fallback to the relevant
    /// memory callback.
    /// This value should be the required access sizes this applies to ORed together.
    /// To detect any access, use: 8 | 16 | 32 | 64.
    std::uint8_t detect_misaligned_access_via_page_table = 0;
    /// Determines if the above option only triggers when the misalignment straddles a
    /// page boundary.
    bool only_detect_misalignment_via_page_table_on_page_boundary = false;

    // Fastmem Pointer
    // This should point to the beginning of a 4GB address space which is in arranged just like
    // what you wish for emulated memory to be. If the host page faults on an address, the JIT
    // will fallback to calling the MemoryRead*/MemoryWrite* callbacks.
    void* fastmem_pointer = nullptr;
    /// Determines if instructions that pagefault should cause recompilation of that block
    /// with fastmem disabled.
    /// Recompiled code will use the page_table if this is available, otherwise memory
    /// accesses will hit the memory callbacks.
    bool recompile_on_fastmem_failure = true;

    /// Determines if we should use the above fastmem_pointer for exclusive reads and
    /// writes. On x64, dynarmic currently relies on x64 cmpxchg semantics which may not
    /// provide fully accurate emulation.
    bool fastmem_exclusive_access = false;
    /// Determines if exclusive access instructions that pagefault should cause
    /// recompilation of that block with fastmem disabled. Recompiled code will use memory
    /// callbacks.
    bool recompile_on_exclusive_fastmem_failure = true;

    // Coprocessors
    std::array<std::shared_ptr<Coprocessor>, 16> coprocessors{};

    /// When set to true, UserCallbacks::InstructionSynchronizationBarrierRaised will be
    /// called when an ISB instruction is executed.
    /// When set to false, ISB will be treated as a NOP instruction.
    bool hook_isb = false;

    /// Hint instructions would cause ExceptionRaised to be called with the appropriate
    /// argument.
    bool hook_hint_instructions = false;

    /// This option relates to translation. Generally when we run into an unpredictable
    /// instruction the ExceptionRaised callback is called. If this is true, we define
    /// definite behaviour for some unpredictable instructions.
    bool define_unpredictable_behaviour = false;

    /// HACK:
    /// This tells the translator a wall clock will be used, thus allowing it
    /// to avoid writting certain unnecessary code only needed for cycle timers.
    bool wall_clock_cntpct = false;

    /// This allows accurately emulating protection fault handlers. If true, we check
    /// for exit after every data memory access by the emulated program.
    bool check_halt_on_memory_access = false;

    /// This option allows you to disable cycle counting. If this is set to false,
    /// AddTicks and GetTicksRemaining are never called, and no cycle counting is done.
    bool enable_cycle_counting = true;

    /// This option relates to the CPSR.E flag. Enabling this option disables modification
    /// of CPSR.E by the emulated program, forcing it to 0.
    /// NOTE: Calling Jit::SetCpsr with CPSR.E=1 while this option is enabled may result
    ///       in unusual behavior.
    bool always_little_endian = false;

    // Minimum size is about 8MiB. Maximum size is about 128MiB (arm64 host) or 2GiB (x64 host).
    // Maximum size is limited by the maximum length of a x86_64 / arm64 jump.
    size_t code_cache_size = 128 * 1024 * 1024;  // bytes

    /// Internal use only
    bool very_verbose_debugging_output = false;
};

}  // namespace A32
}  // namespace Dynarmic
