1 files changed, 173 insertions, 0 deletions

diff --git a/src/core/hle/kernel/address_arbiter.cpp b/src/core/hle/kernel/address_arbiter.cpp
new file mode 100644
index 000000000..e9c8369d7
--- /dev/null
+++ b/src/core/hle/kernel/address_arbiter.cpp
@@ -0,0 +1,173 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/assert.h"
+#include "common/common_funcs.h"
+#include "common/common_types.h"
+#include "core/core.h"
+#include "core/hle/kernel/errors.h"
+#include "core/hle/kernel/kernel.h"
+#include "core/hle/kernel/process.h"
+#include "core/hle/kernel/thread.h"
+#include "core/hle/lock.h"
+#include "core/memory.h"
+
+namespace Kernel {
+namespace AddressArbiter {
+
+// Performs actual address waiting logic.
+static ResultCode WaitForAddress(VAddr address, s64 timeout) {
+    SharedPtr<Thread> current_thread = GetCurrentThread();
+    current_thread->arb_wait_address = address;
+    current_thread->status = THREADSTATUS_WAIT_ARB;
+    current_thread->wakeup_callback = nullptr;
+
+    current_thread->WakeAfterDelay(timeout);
+
+    Core::System::GetInstance().CpuCore(current_thread->processor_id).PrepareReschedule();
+    return RESULT_TIMEOUT;
+}
+
+// Gets the threads waiting on an address.
+static void GetThreadsWaitingOnAddress(std::vector<SharedPtr<Thread>>& waiting_threads,
+                                       VAddr address) {
+    auto RetrieveWaitingThreads =
+        [](size_t core_index, std::vector<SharedPtr<Thread>>& waiting_threads, VAddr arb_addr) {
+            const auto& scheduler = Core::System::GetInstance().Scheduler(core_index);
+            auto& thread_list = scheduler->GetThreadList();
+
+            for (auto& thread : thread_list) {
+                if (thread->arb_wait_address == arb_addr)
+                    waiting_threads.push_back(thread);
+            }
+        };
+
+    // Retrieve a list of all threads that are waiting for this address.
+    RetrieveWaitingThreads(0, waiting_threads, address);
+    RetrieveWaitingThreads(1, waiting_threads, address);
+    RetrieveWaitingThreads(2, waiting_threads, address);
+    RetrieveWaitingThreads(3, waiting_threads, address);
+    // Sort them by priority, such that the highest priority ones come first.
+    std::sort(waiting_threads.begin(), waiting_threads.end(),
+              [](const SharedPtr<Thread>& lhs, const SharedPtr<Thread>& rhs) {
+                  return lhs->current_priority < rhs->current_priority;
+              });
+}
+
+// Wake up num_to_wake (or all) threads in a vector.
+static void WakeThreads(std::vector<SharedPtr<Thread>>& waiting_threads, s32 num_to_wake) {
+    // Only process up to 'target' threads, unless 'target' is <= 0, in which case process
+    // them all.
+    size_t last = waiting_threads.size();
+    if (num_to_wake > 0)
+        last = num_to_wake;
+
+    // Signal the waiting threads.
+    for (size_t i = 0; i < last; i++) {
+        ASSERT(waiting_threads[i]->status = THREADSTATUS_WAIT_ARB);
+        waiting_threads[i]->SetWaitSynchronizationResult(RESULT_SUCCESS);
+        waiting_threads[i]->arb_wait_address = 0;
+        waiting_threads[i]->ResumeFromWait();
+    }
+}
+
+// Signals an address being waited on.
+ResultCode SignalToAddress(VAddr address, s32 num_to_wake) {
+    // Get threads waiting on the address.
+    std::vector<SharedPtr<Thread>> waiting_threads;
+    GetThreadsWaitingOnAddress(waiting_threads, address);
+
+    WakeThreads(waiting_threads, num_to_wake);
+    return RESULT_SUCCESS;
+}
+
+// Signals an address being waited on and increments its value if equal to the value argument.
+ResultCode IncrementAndSignalToAddressIfEqual(VAddr address, s32 value, s32 num_to_wake) {
+    // Ensure that we can write to the address.
+    if (!Memory::IsValidVirtualAddress(address)) {
+        return ERR_INVALID_ADDRESS_STATE;
+    }
+
+    if (static_cast<s32>(Memory::Read32(address)) == value) {
+        Memory::Write32(address, static_cast<u32>(value + 1));
+    } else {
+        return ERR_INVALID_STATE;
+    }
+
+    return SignalToAddress(address, num_to_wake);
+}
+
+// Signals an address being waited on and modifies its value based on waiting thread count if equal
+// to the value argument.
+ResultCode ModifyByWaitingCountAndSignalToAddressIfEqual(VAddr address, s32 value,
+                                                         s32 num_to_wake) {
+    // Ensure that we can write to the address.
+    if (!Memory::IsValidVirtualAddress(address)) {
+        return ERR_INVALID_ADDRESS_STATE;
+    }
+
+    // Get threads waiting on the address.
+    std::vector<SharedPtr<Thread>> waiting_threads;
+    GetThreadsWaitingOnAddress(waiting_threads, address);
+
+    // Determine the modified value depending on the waiting count.
+    s32 updated_value;
+    if (waiting_threads.size() == 0) {
+        updated_value = value - 1;
+    } else if (num_to_wake <= 0 || waiting_threads.size() <= num_to_wake) {
+        updated_value = value + 1;
+    } else {
+        updated_value = value;
+    }
+
+    if (static_cast<s32>(Memory::Read32(address)) == value) {
+        Memory::Write32(address, static_cast<u32>(updated_value));
+    } else {
+        return ERR_INVALID_STATE;
+    }
+
+    WakeThreads(waiting_threads, num_to_wake);
+    return RESULT_SUCCESS;
+}
+
+// Waits on an address if the value passed is less than the argument value, optionally decrementing.
+ResultCode WaitForAddressIfLessThan(VAddr address, s32 value, s64 timeout, bool should_decrement) {
+    // Ensure that we can read the address.
+    if (!Memory::IsValidVirtualAddress(address)) {
+        return ERR_INVALID_ADDRESS_STATE;
+    }
+
+    s32 cur_value = static_cast<s32>(Memory::Read32(address));
+    if (cur_value < value) {
+        Memory::Write32(address, static_cast<u32>(cur_value - 1));
+    } else {
+        return ERR_INVALID_STATE;
+    }
+    // Short-circuit without rescheduling, if timeout is zero.
+    if (timeout == 0) {
+        return RESULT_TIMEOUT;
+    }
+
+    return WaitForAddress(address, timeout);
+}
+
+// Waits on an address if the value passed is equal to the argument value.
+ResultCode WaitForAddressIfEqual(VAddr address, s32 value, s64 timeout) {
+    // Ensure that we can read the address.
+    if (!Memory::IsValidVirtualAddress(address)) {
+        return ERR_INVALID_ADDRESS_STATE;
+    }
+    // Only wait for the address if equal.
+    if (static_cast<s32>(Memory::Read32(address)) != value) {
+        return ERR_INVALID_STATE;
+    }
+    // Short-circuit without rescheduling, if timeout is zero.
+    if (timeout == 0) {
+        return RESULT_TIMEOUT;
+    }
+
+    return WaitForAddress(address, timeout);
+}
+} // namespace AddressArbiter
+} // namespace Kernel