0cbcd6ec9a
As means to pave the way for getting rid of global state within core, This eliminates kernel global state by removing all globals. Instead this introduces a KernelCore class which acts as a kernel instance. This instance lives in the System class, which keeps its lifetime contained to the lifetime of the System class. This also forces the kernel types to actually interact with the main kernel instance itself instead of having transient kernel state placed all over several translation units, keeping everything together. It also has a nice consequence of making dependencies much more explicit. This also makes our initialization a tad bit more correct. Previously we were creating a kernel process before the actual kernel was initialized, which doesn't really make much sense. The KernelCore class itself follows the PImpl idiom, which allows keeping all the implementation details sealed away from everything else, which forces the use of the exposed API and allows us to avoid any unnecessary inclusions within the main kernel header.
124 lines
4.6 KiB
C++
124 lines
4.6 KiB
C++
// Copyright 2014 Citra Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#pragma once
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#include <array>
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#include <cstddef>
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#include "common/common_types.h"
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#include "core/hle/kernel/object.h"
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#include "core/hle/result.h"
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namespace Kernel {
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enum KernelHandle : Handle {
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CurrentThread = 0xFFFF8000,
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CurrentProcess = 0xFFFF8001,
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};
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/**
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* This class allows the creation of Handles, which are references to objects that can be tested
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* for validity and looked up. Here they are used to pass references to kernel objects to/from the
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* emulated process. it has been designed so that it follows the same handle format and has
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* approximately the same restrictions as the handle manager in the CTR-OS.
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*
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* Handles contain two sub-fields: a slot index (bits 31:15) and a generation value (bits 14:0).
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* The slot index is used to index into the arrays in this class to access the data corresponding
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* to the Handle.
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*
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* To prevent accidental use of a freed Handle whose slot has already been reused, a global counter
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* is kept and incremented every time a Handle is created. This is the Handle's "generation". The
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* value of the counter is stored into the Handle as well as in the handle table (in the
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* "generations" array). When looking up a handle, the Handle's generation must match with the
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* value stored on the class, otherwise the Handle is considered invalid.
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*
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* To find free slots when allocating a Handle without needing to scan the entire object array, the
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* generations field of unallocated slots is re-purposed as a linked list of indices to free slots.
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* When a Handle is created, an index is popped off the list and used for the new Handle. When it
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* is destroyed, it is again pushed onto the list to be re-used by the next allocation. It is
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* likely that this allocation strategy differs from the one used in CTR-OS, but this hasn't been
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* verified and isn't likely to cause any problems.
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*/
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class HandleTable final : NonCopyable {
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public:
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HandleTable();
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/**
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* Allocates a handle for the given object.
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* @return The created Handle or one of the following errors:
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* - `ERR_HANDLE_TABLE_FULL`: the maximum number of handles has been exceeded.
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*/
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ResultVal<Handle> Create(SharedPtr<Object> obj);
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/**
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* Returns a new handle that points to the same object as the passed in handle.
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* @return The duplicated Handle or one of the following errors:
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* - `ERR_INVALID_HANDLE`: an invalid handle was passed in.
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* - Any errors returned by `Create()`.
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*/
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ResultVal<Handle> Duplicate(Handle handle);
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/**
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* Closes a handle, removing it from the table and decreasing the object's ref-count.
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* @return `RESULT_SUCCESS` or one of the following errors:
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* - `ERR_INVALID_HANDLE`: an invalid handle was passed in.
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*/
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ResultCode Close(Handle handle);
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/// Checks if a handle is valid and points to an existing object.
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bool IsValid(Handle handle) const;
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/**
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* Looks up a handle.
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* @return Pointer to the looked-up object, or `nullptr` if the handle is not valid.
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*/
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SharedPtr<Object> GetGeneric(Handle handle) const;
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/**
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* Looks up a handle while verifying its type.
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* @return Pointer to the looked-up object, or `nullptr` if the handle is not valid or its
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* type differs from the requested one.
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*/
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template <class T>
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SharedPtr<T> Get(Handle handle) const {
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return DynamicObjectCast<T>(GetGeneric(handle));
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}
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/// Closes all handles held in this table.
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void Clear();
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private:
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/**
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* This is the maximum limit of handles allowed per process in CTR-OS. It can be further
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* reduced by ExHeader values, but this is not emulated here.
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*/
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static const size_t MAX_COUNT = 4096;
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static u16 GetSlot(Handle handle) {
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return handle >> 15;
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}
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static u16 GetGeneration(Handle handle) {
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return handle & 0x7FFF;
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}
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/// Stores the Object referenced by the handle or null if the slot is empty.
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std::array<SharedPtr<Object>, MAX_COUNT> objects;
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/**
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* The value of `next_generation` when the handle was created, used to check for validity. For
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* empty slots, contains the index of the next free slot in the list.
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*/
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std::array<u16, MAX_COUNT> generations;
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/**
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* Global counter of the number of created handles. Stored in `generations` when a handle is
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* created, and wraps around to 1 when it hits 0x8000.
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*/
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u16 next_generation;
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/// Head of the free slots linked list.
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u16 next_free_slot;
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};
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} // namespace Kernel
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