From 600c14b3f01803ea55653c59046a2250b9a0511d Mon Sep 17 00:00:00 2001
From: gibbed <rick@gibbed.us>
Date: Fri, 7 Jan 2022 09:20:09 -0600
Subject: [PATCH] [xboxknrl] Implement ExTryToAcquireRWLShared.

[xboxknrl] Implement ExTryToAcquireReadWriteLockShared.
---
 .../kernel/xboxkrnl/xboxkrnl_threading.cc     | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/xenia/kernel/xboxkrnl/xboxkrnl_threading.cc b/src/xenia/kernel/xboxkrnl/xboxkrnl_threading.cc
index c59a21dc8..0fa37bda8 100644
--- a/src/xenia/kernel/xboxkrnl/xboxkrnl_threading.cc
+++ b/src/xenia/kernel/xboxkrnl/xboxkrnl_threading.cc
@@ -1236,6 +1236,26 @@ void ExAcquireReadWriteLockShared(pointer_t<X_ERWLOCK> lock_ptr) {
 DECLARE_XBOXKRNL_EXPORT2(ExAcquireReadWriteLockShared, kThreading, kImplemented,
                          kBlocking);
 
+dword_result_t ExTryToAcquireReadWriteLockShared(
+    pointer_t<X_ERWLOCK> lock_ptr) {
+  auto old_irql = xeKeKfAcquireSpinLock(&lock_ptr->spin_lock);
+
+  uint32_t result;
+  if (lock_ptr->lock_count < 0 ||
+      (lock_ptr->readers_entry_count && !lock_ptr->writers_waiting_count)) {
+    lock_ptr->lock_count++;
+    lock_ptr->readers_entry_count++;
+    result = 1;
+  } else {
+    result = 0;
+  }
+
+  xeKeKfReleaseSpinLock(&lock_ptr->spin_lock, old_irql);
+  return result;
+}
+DECLARE_XBOXKRNL_EXPORT1(ExTryToAcquireReadWriteLockShared, kThreading,
+                         kImplemented);
+
 void ExReleaseReadWriteLock(pointer_t<X_ERWLOCK> lock_ptr) {
   auto old_irql = xeKeKfAcquireSpinLock(&lock_ptr->spin_lock);