From 9d71ce88cee58d2e171ec5ed82daf075112fb422 Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Thu, 21 Jun 2018 01:40:29 -0600
Subject: Kernel/Arbiters: Implement WaitForAddress

---
 src/core/hle/kernel/address_arbiter.cpp | 59 ++++++++++++++++++++++++++++++---
 1 file changed, 55 insertions(+), 4 deletions(-)

(limited to 'src/core/hle/kernel/address_arbiter.cpp')

diff --git a/src/core/hle/kernel/address_arbiter.cpp b/src/core/hle/kernel/address_arbiter.cpp
index cfd2c1590..367c4520d 100644
--- a/src/core/hle/kernel/address_arbiter.cpp
+++ b/src/core/hle/kernel/address_arbiter.cpp
@@ -5,14 +5,31 @@
 #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.
+        ResultCode WaitForAddress(VAddr address, s64 timeout) {
+            SharedPtr<Thread> current_thread = GetCurrentThread();
+            current_thread->arb_wait_address = address;
+            current_thread->arb_wait_result = RESULT_TIMEOUT;
+            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_SUCCESS;
+        }
+
         // Signals an address being waited on.
         ResultCode SignalToAddress(VAddr address, s32 value, s32 num_to_wake) {
             // TODO
@@ -33,14 +50,48 @@ namespace Kernel {
 
         // 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) {
-            // TODO
-            return RESULT_SUCCESS;
+            // Ensure that we can read the address.
+            if (!Memory::IsValidVirtualAddress(address)) {
+                return ERR_INVALID_ADDRESS_STATE;
+            }
+
+            s32 cur_value;
+            // Get value, decrementing if less than
+            {
+                // Decrement if less than must be an atomic operation.
+                std::lock_guard<std::recursive_mutex> lock(HLE::g_hle_lock);
+                cur_value = (s32)Memory::Read32(address);
+                if (cur_value < value) {
+                    Memory::Write32(address, (u32)(cur_value - 1));
+                }
+            }
+            if (cur_value >= value) {
+                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) {
-            // TODO
-            return RESULT_SUCCESS;
+            // Ensure that we can read the address.
+            if (!Memory::IsValidVirtualAddress(address)) {
+                return ERR_INVALID_ADDRESS_STATE;
+            }
+            // Only wait for the address if equal.
+            if ((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
\ No newline at end of file
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