From cf7c467637d139d12486a31dc0211c9cbdd4d3a0 Mon Sep 17 00:00:00 2001
From: belliash <belliash@codingworkshop.eu.org>
Date: Sun, 29 Oct 2023 11:48:31 +0100
Subject: [PATCH] Implement RtlInterlockedExchangePointer() routine

---
 xtoskrnl/includes/rtl.h |  5 +++++
 xtoskrnl/rtl/intrin.c   | 22 ++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/xtoskrnl/includes/rtl.h b/xtoskrnl/includes/rtl.h
index b4bad2c..fb66e69 100644
--- a/xtoskrnl/includes/rtl.h
+++ b/xtoskrnl/includes/rtl.h
@@ -233,6 +233,11 @@ XTFASTCALL
 LONG_PTR
 RtlInterlockedDecrementLongPtr(IN VOLATILE PLONG_PTR Addend);
 
+XTFASTCALL
+PVOID
+RtlInterlockedExchangePointer(IN VOLATILE PVOID *Destination,
+                              IN PVOID Value);
+
 XTCDECL
 BOOLEAN
 RtlListEmpty(PLIST_ENTRY ListHead);
diff --git a/xtoskrnl/rtl/intrin.c b/xtoskrnl/rtl/intrin.c
index 4b9df3c..d5413f8 100644
--- a/xtoskrnl/rtl/intrin.c
+++ b/xtoskrnl/rtl/intrin.c
@@ -50,3 +50,25 @@ RtlInterlockedDecrementLongPtr(IN VOLATILE PLONG_PTR Addend)
 {
     return (LONG_PTR)__sync_sub_and_fetch(Addend, 1);
 }
+
+/**
+ * Performs an atomic assignment of the value to the pointer variable.
+ *
+ * @param Destination
+ *        Supplies a pointer to the variable to be set.
+ *
+ * @param Value
+ *        Supplies a value to set.
+ *
+ * @return This routine returns the initial value of the pointer variable.
+ *
+ * @since XT 1.0
+ */
+XTFASTCALL
+PVOID
+RtlInterlockedExchangePointer(IN VOLATILE PVOID *Destination,
+                              IN PVOID Value)
+{
+    __sync_synchronize();
+    return (void *)__sync_lock_test_and_set(Destination, Value);
+}