citra/src/core/hle/kernel/kernel.cpp

// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <algorithm>
#include "common/assert.h"
#include "common/logging/log.h"
#include "core/hle/config_mem.h"
#include "core/hle/kernel/kernel.h"
#include "core/hle/kernel/memory.h"
#include "core/hle/kernel/process.h"
#include "core/hle/kernel/resource_limit.h"
#include "core/hle/kernel/thread.h"
#include "core/hle/kernel/timer.h"
#include "core/hle/shared_page.h"

namespace Kernel {

unsigned int Object::next_object_id;
HandleTable g_handle_table;

void WaitObject::AddWaitingThread(SharedPtr<Thread> thread) {
    auto itr = std::find(waiting_threads.begin(), waiting_threads.end(), thread);
    if (itr == waiting_threads.end())
        waiting_threads.push_back(std::move(thread));
}

void WaitObject::RemoveWaitingThread(Thread* thread) {
    auto itr = std::find(waiting_threads.begin(), waiting_threads.end(), thread);
    if (itr != waiting_threads.end())
        waiting_threads.erase(itr);
}

SharedPtr<Thread> WaitObject::GetHighestPriorityReadyThread() {
    // Remove the threads that are ready or already running from our waitlist
    waiting_threads.erase(std::remove_if(waiting_threads.begin(), waiting_threads.end(), [](const SharedPtr<Thread>& thread) -> bool {
        return thread->status == THREADSTATUS_RUNNING || thread->status == THREADSTATUS_READY;
    }), waiting_threads.end());

    if (waiting_threads.empty())
        return nullptr;

    auto candidate_threads = waiting_threads;

    // Eliminate all threads that are waiting on more than one object, and not all of said objects are ready
    candidate_threads.erase(std::remove_if(candidate_threads.begin(), candidate_threads.end(), [](const SharedPtr<Thread>& thread) -> bool {
        return std::any_of(thread->wait_objects.begin(), thread->wait_objects.end(), [](const SharedPtr<WaitObject>& object) -> bool {
            return object->ShouldWait();
        });
    }), candidate_threads.end());

    // Return the thread with the lowest priority value (The one with the highest priority)
    auto thread_itr = std::min_element(candidate_threads.begin(), candidate_threads.end(), [](const SharedPtr<Thread>& lhs, const SharedPtr<Thread>& rhs) {
        return lhs->current_priority < rhs->current_priority;
    });

    if (thread_itr == candidate_threads.end())
        return nullptr;

    return *thread_itr;
}

void WaitObject::WakeupAllWaitingThreads() {
    // Wake up all threads that can be awoken, in priority order
    while (auto thread = GetHighestPriorityReadyThread()) {
        if (thread->wait_objects.empty()) {
            Acquire();
            // Set the output index of the WaitSynchronizationN call to the index of this object.
            if (thread->wait_set_output) {
                thread->SetWaitSynchronizationOutput(thread->GetWaitObjectIndex(this));
                thread->wait_set_output = false;
            }
        } else {
            for (auto object : thread->wait_objects) {
                object->Acquire();
                // Remove the thread from the object's waitlist
                object->RemoveWaitingThread(thread.get());
            }
            // Note: This case doesn't update the output index of WaitSynchronizationN.
            // Clear the thread's waitlist
            thread->wait_objects.clear();
        }

        // Set the result of the call to WaitSynchronization to RESULT_SUCCESS
        thread->SetWaitSynchronizationResult(RESULT_SUCCESS);
        thread->ResumeFromWait();
        // Note: Removing the thread from the object's waitlist will be done by GetHighestPriorityReadyThread
    }
}

const std::vector<SharedPtr<Thread>>& WaitObject::GetWaitingThreads() const {
    return waiting_threads;
}

HandleTable::HandleTable() {
    next_generation = 1;
    Clear();
}

ResultVal<Handle> HandleTable::Create(SharedPtr<Object> obj) {
    DEBUG_ASSERT(obj != nullptr);

    u16 slot = next_free_slot;
    if (slot >= generations.size()) {
        LOG_ERROR(Kernel, "Unable to allocate Handle, too many slots in use.");
        return ERR_OUT_OF_HANDLES;
    }
    next_free_slot = generations[slot];

    u16 generation = next_generation++;

    // Overflow count so it fits in the 15 bits dedicated to the generation in the handle.
    // CTR-OS doesn't use generation 0, so skip straight to 1.
    if (next_generation >= (1 << 15))
        next_generation = 1;

    generations[slot] = generation;
    objects[slot] = std::move(obj);

    Handle handle = generation | (slot << 15);
    return MakeResult<Handle>(handle);
}

ResultVal<Handle> HandleTable::Duplicate(Handle handle) {
    SharedPtr<Object> object = GetGeneric(handle);
    if (object == nullptr) {
        LOG_ERROR(Kernel, "Tried to duplicate invalid handle: %08X", handle);
        return ERR_INVALID_HANDLE;
    }
    return Create(std::move(object));
}

ResultCode HandleTable::Close(Handle handle) {
    if (!IsValid(handle))
        return ERR_INVALID_HANDLE;

    u16 slot = GetSlot(handle);

    objects[slot] = nullptr;

    generations[slot] = next_free_slot;
    next_free_slot = slot;
    return RESULT_SUCCESS;
}

bool HandleTable::IsValid(Handle handle) const {
    size_t slot = GetSlot(handle);
    u16 generation = GetGeneration(handle);

    return slot < MAX_COUNT && objects[slot] != nullptr && generations[slot] == generation;
}

SharedPtr<Object> HandleTable::GetGeneric(Handle handle) const {
    if (handle == CurrentThread) {
        return GetCurrentThread();
    } else if (handle == CurrentProcess) {
        return g_current_process;
    }

    if (!IsValid(handle)) {
        return nullptr;
    }
    return objects[GetSlot(handle)];
}

void HandleTable::Clear() {
    for (u16 i = 0; i < MAX_COUNT; ++i) {
        generations[i] = i + 1;
        objects[i] = nullptr;
    }
    next_free_slot = 0;
}

/// Initialize the kernel
void Init(u32 system_mode) {
    ConfigMem::Init();
    SharedPage::Init();

    Kernel::MemoryInit(system_mode);

    Kernel::ResourceLimitsInit();
    Kernel::ThreadingInit();
    Kernel::TimersInit();

    Object::next_object_id = 0;
    // TODO(Subv): Start the process ids from 10 for now, as lower PIDs are
    // reserved for low-level services
    Process::next_process_id = 10;
}

/// Shutdown the kernel
void Shutdown() {
    g_handle_table.Clear(); // Free all kernel objects

    Kernel::ThreadingShutdown();
    g_current_process = nullptr;

    Kernel::TimersShutdown();
    Kernel::ResourceLimitsShutdown();
    Kernel::MemoryShutdown();
}

} // namespace