2 files changed, 444 insertions, 0 deletions

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index adabe8dbd..4de159119 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -153,6 +153,7 @@ add_library(core STATIC
     hle/kernel/hle_ipc.cpp
     hle/kernel/hle_ipc.h
     hle/kernel/k_affinity_mask.h
+    hle/kernel/k_priority_queue.h
     hle/kernel/kernel.cpp
     hle/kernel/kernel.h
     hle/kernel/memory/address_space_info.cpp
diff --git a/src/core/hle/kernel/k_priority_queue.h b/src/core/hle/kernel/k_priority_queue.h
new file mode 100644
index 000000000..88e4e1ed4
--- /dev/null
+++ b/src/core/hle/kernel/k_priority_queue.h
@@ -0,0 +1,443 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+// This file references various implementation details from Atmosphere, an open-source firmware for
+// the Nintendo Switch. Copyright 2018-2020 Atmosphere-NX.
+
+#pragma once
+
+#include "common/assert.h"
+#include "common/bit_set.h"
+#include "common/bit_util.h"
+#include "common/common_types.h"
+
+namespace Kernel {
+
+class Thread;
+
+template <typename T>
+concept KPriorityQueueAffinityMask = !std::is_reference<T>::value && requires(T & t) {
+    { t.GetAffinityMask() }
+    ->std::convertible_to<u64>;
+    {t.SetAffinityMask(std::declval<u64>())};
+
+    { t.GetAffinity(std::declval<int32_t>()) }
+    ->std::same_as<bool>;
+    {t.SetAffinity(std::declval<int32_t>(), std::declval<bool>())};
+    {t.SetAll()};
+};
+
+template <typename T>
+concept KPriorityQueueMember = !std::is_reference<T>::value && requires(T & t) {
+    {typename T::QueueEntry()};
+    {(typename T::QueueEntry()).Initialize()};
+    {(typename T::QueueEntry()).SetPrev(std::addressof(t))};
+    {(typename T::QueueEntry()).SetNext(std::addressof(t))};
+    { (typename T::QueueEntry()).GetNext() }
+    ->std::same_as<T*>;
+    { (typename T::QueueEntry()).GetPrev() }
+    ->std::same_as<T*>;
+    { t.GetPriorityQueueEntry(std::declval<s32>()) }
+    ->std::same_as<typename T::QueueEntry&>;
+
+    {t.GetAffinityMask()};
+    { typename std::remove_cvref<decltype(t.GetAffinityMask())>::type() }
+    ->KPriorityQueueAffinityMask;
+
+    { t.GetActiveCore() }
+    ->std::convertible_to<s32>;
+    { t.GetPriority() }
+    ->std::convertible_to<s32>;
+};
+
+template <typename Member, size_t _NumCores, int LowestPriority, int HighestPriority>
+requires KPriorityQueueMember<Member> class KPriorityQueue {
+public:
+    using AffinityMaskType = typename std::remove_cv<typename std::remove_reference<decltype(
+        std::declval<Member>().GetAffinityMask())>::type>::type;
+
+    static_assert(LowestPriority >= 0);
+    static_assert(HighestPriority >= 0);
+    static_assert(LowestPriority >= HighestPriority);
+    static constexpr size_t NumPriority = LowestPriority - HighestPriority + 1;
+    static constexpr size_t NumCores = _NumCores;
+
+    static constexpr bool IsValidCore(s32 core) {
+        return 0 <= core && core < static_cast<s32>(NumCores);
+    }
+
+    static constexpr bool IsValidPriority(s32 priority) {
+        return HighestPriority <= priority && priority <= LowestPriority + 1;
+    }
+
+private:
+    using Entry = typename Member::QueueEntry;
+
+public:
+    class KPerCoreQueue {
+    private:
+        Entry root[NumCores];
+
+    public:
+        constexpr KPerCoreQueue() : root() {
+            for (size_t i = 0; i < NumCores; i++) {
+                this->root[i].Initialize();
+            }
+        }
+
+        constexpr bool PushBack(s32 core, Member* member) {
+            /* Get the entry associated with the member. */
+            Entry& member_entry = member->GetPriorityQueueEntry(core);
+
+            /* Get the entry associated with the end of the queue. */
+            Member* tail = this->root[core].GetPrev();
+            Entry& tail_entry =
+                (tail != nullptr) ? tail->GetPriorityQueueEntry(core) : this->root[core];
+
+            /* Link the entries. */
+            member_entry.SetPrev(tail);
+            member_entry.SetNext(nullptr);
+            tail_entry.SetNext(member);
+            this->root[core].SetPrev(member);
+
+            return (tail == nullptr);
+        }
+
+        constexpr bool PushFront(s32 core, Member* member) {
+            /* Get the entry associated with the member. */
+            Entry& member_entry = member->GetPriorityQueueEntry(core);
+
+            /* Get the entry associated with the front of the queue. */
+            Member* head = this->root[core].GetNext();
+            Entry& head_entry =
+                (head != nullptr) ? head->GetPriorityQueueEntry(core) : this->root[core];
+
+            /* Link the entries. */
+            member_entry.SetPrev(nullptr);
+            member_entry.SetNext(head);
+            head_entry.SetPrev(member);
+            this->root[core].SetNext(member);
+
+            return (head == nullptr);
+        }
+
+        constexpr bool Remove(s32 core, Member* member) {
+            /* Get the entry associated with the member. */
+            Entry& member_entry = member->GetPriorityQueueEntry(core);
+
+            /* Get the entries associated with next and prev. */
+            Member* prev = member_entry.GetPrev();
+            Member* next = member_entry.GetNext();
+            Entry& prev_entry =
+                (prev != nullptr) ? prev->GetPriorityQueueEntry(core) : this->root[core];
+            Entry& next_entry =
+                (next != nullptr) ? next->GetPriorityQueueEntry(core) : this->root[core];
+
+            /* Unlink. */
+            prev_entry.SetNext(next);
+            next_entry.SetPrev(prev);
+
+            return (this->GetFront(core) == nullptr);
+        }
+
+        constexpr Member* GetFront(s32 core) const {
+            return this->root[core].GetNext();
+        }
+    };
+
+    class KPriorityQueueImpl {
+    private:
+        KPerCoreQueue queues[NumPriority];
+        Common::BitSet64<NumPriority> available_priorities[NumCores];
+
+    public:
+        constexpr KPriorityQueueImpl() : queues(), available_priorities() { /* ... */
+        }
+
+        constexpr void PushBack(s32 priority, s32 core, Member* member) {
+            ASSERT(IsValidCore(core));
+            ASSERT(IsValidPriority(priority));
+
+            if (priority <= LowestPriority) {
+                if (this->queues[priority].PushBack(core, member)) {
+                    this->available_priorities[core].SetBit(priority);
+                }
+            }
+        }
+
+        constexpr void PushFront(s32 priority, s32 core, Member* member) {
+            ASSERT(IsValidCore(core));
+            ASSERT(IsValidPriority(priority));
+
+            if (priority <= LowestPriority) {
+                if (this->queues[priority].PushFront(core, member)) {
+                    this->available_priorities[core].SetBit(priority);
+                }
+            }
+        }
+
+        constexpr void Remove(s32 priority, s32 core, Member* member) {
+            ASSERT(IsValidCore(core));
+            ASSERT(IsValidPriority(priority));
+
+            if (priority <= LowestPriority) {
+                if (this->queues[priority].Remove(core, member)) {
+                    this->available_priorities[core].ClearBit(priority);
+                }
+            }
+        }
+
+        constexpr Member* GetFront(s32 core) const {
+            ASSERT(IsValidCore(core));
+
+            const s32 priority =
+                static_cast<s32>(this->available_priorities[core].CountLeadingZero());
+            if (priority <= LowestPriority) {
+                return this->queues[priority].GetFront(core);
+            } else {
+                return nullptr;
+            }
+        }
+
+        constexpr Member* GetFront(s32 priority, s32 core) const {
+            ASSERT(IsValidCore(core));
+            ASSERT(IsValidPriority(priority));
+
+            if (priority <= LowestPriority) {
+                return this->queues[priority].GetFront(core);
+            } else {
+                return nullptr;
+            }
+        }
+
+        constexpr Member* GetNext(s32 core, const Member* member) const {
+            ASSERT(IsValidCore(core));
+
+            Member* next = member->GetPriorityQueueEntry(core).GetNext();
+            if (next == nullptr) {
+                const s32 priority = static_cast<s32>(
+                    this->available_priorities[core].GetNextSet(member->GetPriority()));
+                if (priority <= LowestPriority) {
+                    next = this->queues[priority].GetFront(core);
+                }
+            }
+            return next;
+        }
+
+        constexpr void MoveToFront(s32 priority, s32 core, Member* member) {
+            ASSERT(IsValidCore(core));
+            ASSERT(IsValidPriority(priority));
+
+            if (priority <= LowestPriority) {
+                this->queues[priority].Remove(core, member);
+                this->queues[priority].PushFront(core, member);
+            }
+        }
+
+        constexpr Member* MoveToBack(s32 priority, s32 core, Member* member) {
+            ASSERT(IsValidCore(core));
+            ASSERT(IsValidPriority(priority));
+
+            if (priority <= LowestPriority) {
+                this->queues[priority].Remove(core, member);
+                this->queues[priority].PushBack(core, member);
+                return this->queues[priority].GetFront(core);
+            } else {
+                return nullptr;
+            }
+        }
+    };
+
+private:
+    KPriorityQueueImpl scheduled_queue;
+    KPriorityQueueImpl suggested_queue;
+
+private:
+    constexpr void ClearAffinityBit(u64& affinity, s32 core) {
+        affinity &= ~(u64(1ul) << core);
+    }
+
+    constexpr s32 GetNextCore(u64& affinity) {
+        const s32 core = Common::CountTrailingZeroes64(affinity);
+        ClearAffinityBit(affinity, core);
+        return core;
+    }
+
+    constexpr void PushBack(s32 priority, Member* member) {
+        ASSERT(IsValidPriority(priority));
+
+        /* Push onto the scheduled queue for its core, if we can. */
+        u64 affinity = member->GetAffinityMask().GetAffinityMask();
+        if (const s32 core = member->GetActiveCore(); core >= 0) {
+            this->scheduled_queue.PushBack(priority, core, member);
+            ClearAffinityBit(affinity, core);
+        }
+
+        /* And suggest the thread for all other cores. */
+        while (affinity) {
+            this->suggested_queue.PushBack(priority, GetNextCore(affinity), member);
+        }
+    }
+
+    constexpr void PushFront(s32 priority, Member* member) {
+        ASSERT(IsValidPriority(priority));
+
+        /* Push onto the scheduled queue for its core, if we can. */
+        u64 affinity = member->GetAffinityMask().GetAffinityMask();
+        if (const s32 core = member->GetActiveCore(); core >= 0) {
+            this->scheduled_queue.PushFront(priority, core, member);
+            ClearAffinityBit(affinity, core);
+        }
+
+        /* And suggest the thread for all other cores. */
+        /* Note: Nintendo pushes onto the back of the suggested queue, not the front. */
+        while (affinity) {
+            this->suggested_queue.PushBack(priority, GetNextCore(affinity), member);
+        }
+    }
+
+    constexpr void Remove(s32 priority, Member* member) {
+        ASSERT(IsValidPriority(priority));
+
+        /* Remove from the scheduled queue for its core. */
+        u64 affinity = member->GetAffinityMask().GetAffinityMask();
+        if (const s32 core = member->GetActiveCore(); core >= 0) {
+            this->scheduled_queue.Remove(priority, core, member);
+            ClearAffinityBit(affinity, core);
+        }
+
+        /* Remove from the suggested queue for all other cores. */
+        while (affinity) {
+            this->suggested_queue.Remove(priority, GetNextCore(affinity), member);
+        }
+    }
+
+public:
+    constexpr KPriorityQueue() : scheduled_queue(), suggested_queue() { /* ... */
+    }
+
+    /* Getters. */
+    constexpr Member* GetScheduledFront(s32 core) const {
+        return this->scheduled_queue.GetFront(core);
+    }
+
+    constexpr Member* GetScheduledFront(s32 core, s32 priority) const {
+        return this->scheduled_queue.GetFront(priority, core);
+    }
+
+    constexpr Member* GetSuggestedFront(s32 core) const {
+        return this->suggested_queue.GetFront(core);
+    }
+
+    constexpr Member* GetSuggestedFront(s32 core, s32 priority) const {
+        return this->suggested_queue.GetFront(priority, core);
+    }
+
+    constexpr Member* GetScheduledNext(s32 core, const Member* member) const {
+        return this->scheduled_queue.GetNext(core, member);
+    }
+
+    constexpr Member* GetSuggestedNext(s32 core, const Member* member) const {
+        return this->suggested_queue.GetNext(core, member);
+    }
+
+    constexpr Member* GetSamePriorityNext(s32 core, const Member* member) const {
+        return member->GetPriorityQueueEntry(core).GetNext();
+    }
+
+    /* Mutators. */
+    constexpr void PushBack(Member* member) {
+        this->PushBack(member->GetPriority(), member);
+    }
+
+    constexpr void Remove(Member* member) {
+        this->Remove(member->GetPriority(), member);
+    }
+
+    constexpr void MoveToScheduledFront(Member* member) {
+        this->scheduled_queue.MoveToFront(member->GetPriority(), member->GetActiveCore(), member);
+    }
+
+    constexpr Thread* MoveToScheduledBack(Member* member) {
+        return this->scheduled_queue.MoveToBack(member->GetPriority(), member->GetActiveCore(),
+                                                member);
+    }
+
+    /* First class fancy operations. */
+    constexpr void ChangePriority(s32 prev_priority, bool is_running, Member* member) {
+        ASSERT(IsValidPriority(prev_priority));
+
+        /* Remove the member from the queues. */
+        const s32 new_priority = member->GetPriority();
+        this->Remove(prev_priority, member);
+
+        /* And enqueue. If the member is running, we want to keep it running. */
+        if (is_running) {
+            this->PushFront(new_priority, member);
+        } else {
+            this->PushBack(new_priority, member);
+        }
+    }
+
+    constexpr void ChangeAffinityMask(s32 prev_core, const AffinityMaskType& prev_affinity,
+                                      Member* member) {
+        /* Get the new information. */
+        const s32 priority = member->GetPriority();
+        const AffinityMaskType& new_affinity = member->GetAffinityMask();
+        const s32 new_core = member->GetActiveCore();
+
+        /* Remove the member from all queues it was in before. */
+        for (s32 core = 0; core < static_cast<s32>(NumCores); core++) {
+            if (prev_affinity.GetAffinity(core)) {
+                if (core == prev_core) {
+                    this->scheduled_queue.Remove(priority, core, member);
+                } else {
+                    this->suggested_queue.Remove(priority, core, member);
+                }
+            }
+        }
+
+        /* And add the member to all queues it should be in now. */
+        for (s32 core = 0; core < static_cast<s32>(NumCores); core++) {
+            if (new_affinity.GetAffinity(core)) {
+                if (core == new_core) {
+                    this->scheduled_queue.PushBack(priority, core, member);
+                } else {
+                    this->suggested_queue.PushBack(priority, core, member);
+                }
+            }
+        }
+    }
+
+    constexpr void ChangeCore(s32 prev_core, Member* member, bool to_front = false) {
+        /* Get the new information. */
+        const s32 new_core = member->GetActiveCore();
+        const s32 priority = member->GetPriority();
+
+        /* We don't need to do anything if the core is the same. */
+        if (prev_core != new_core) {
+            /* Remove from the scheduled queue for the previous core. */
+            if (prev_core >= 0) {
+                this->scheduled_queue.Remove(priority, prev_core, member);
+            }
+
+            /* Remove from the suggested queue and add to the scheduled queue for the new core. */
+            if (new_core >= 0) {
+                this->suggested_queue.Remove(priority, new_core, member);
+                if (to_front) {
+                    this->scheduled_queue.PushFront(priority, new_core, member);
+                } else {
+                    this->scheduled_queue.PushBack(priority, new_core, member);
+                }
+            }
+
+            /* Add to the suggested queue for the previous core. */
+            if (prev_core >= 0) {
+                this->suggested_queue.PushBack(priority, prev_core, member);
+            }
+        }
+    }
+};
+
+} // namespace Kernel