From 362b9ceb7cc3c7564d62006f58d32b2d82fd7cc9 Mon Sep 17 00:00:00 2001
From: Bill Zissimopoulos <billziss@navimatics.com>
Date: Mon, 17 Jan 2022 14:33:34 +0000
Subject: [PATCH] inc: fsctl.h: atomics

---
 inc/winfsp/fsctl.h | 87 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/inc/winfsp/fsctl.h b/inc/winfsp/fsctl.h
index 11c8dff7..62a15091 100644
--- a/inc/winfsp/fsctl.h
+++ b/inc/winfsp/fsctl.h
@@ -699,6 +699,93 @@ FSP_API NTSTATUS FspMountSet(FSP_MOUNT_DESC *Desc);
 FSP_API NTSTATUS FspMountRemove(FSP_MOUNT_DESC *Desc);
 #endif
 
+/*
+ * Atomics
+ *
+ * See https://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html (https://archive.is/mJfFX)
+ */
+#if _MSC_VER >= 1920 /* VS2019 or later */
+__int32 __iso_volatile_load32(const volatile __int32 *);
+void __iso_volatile_store32(volatile __int32 *, __int32);
+__int64 __iso_volatile_load64(const volatile __int64 *);
+void __iso_volatile_store64(volatile __int64 *, __int64);
+#define FSP_ATOMIC_VOLATILE_LOAD32(p)   __iso_volatile_load32(p)
+#define FSP_ATOMIC_VOLATILE_STORE32(p,v)__iso_volatile_store32(p,v)
+#define FSP_ATOMIC_VOLATILE_LOAD64(p)   __iso_volatile_load64(p)
+#define FSP_ATOMIC_VOLATILE_STORE64(p,v)__iso_volatile_store64(p,v)
+#else
+#define FSP_ATOMIC_VOLATILE_LOAD32(p)   (*(p))
+#define FSP_ATOMIC_VOLATILE_STORE32(p,v)(*(p) = (v))
+#define FSP_ATOMIC_VOLATILE_LOAD64(p)   (*(p))
+#define FSP_ATOMIC_VOLATILE_STORE64(p,v)(*(p) = (v))
+#endif
+static inline INT32 FspAtomicLoad32(INT32 volatile *p)
+{
+#if defined(_M_ARM64)
+    void __dmb(unsigned int);
+    INT32 v = FSP_ATOMIC_VOLATILE_LOAD32(p);
+    __dmb(0xb);
+    return v;
+
+#elif defined(_M_X64) || defined(_M_IX86)
+    void _ReadWriteBarrier(void);
+    INT32 v = FSP_ATOMIC_VOLATILE_LOAD32(p);
+    _ReadWriteBarrier();
+    return v;
+
+#endif
+}
+static inline VOID FspAtomicStore32(INT32 volatile *p, INT32 v)
+{
+#if defined(_M_ARM64)
+    void __dmb(unsigned int);
+    __dmb(0xb);
+    FSP_ATOMIC_VOLATILE_STORE32(p, v);
+    __dmb(0xb);
+
+#elif defined(_M_X64) || defined(_M_IX86)
+    long _InterlockedExchange(long volatile *, long);
+    _InterlockedExchange((long volatile *)p, v);
+
+#endif
+}
+static inline VOID *FspAtomicLoadPointer(VOID *volatile *p)
+{
+#if defined(_M_ARM64)
+    void __dmb(unsigned int);
+    VOID *v = (VOID *)FSP_ATOMIC_VOLATILE_LOAD64((__int64 volatile *)(p));
+    __dmb(0xb);
+    return v;
+
+#elif defined(_M_X64)
+    void _ReadWriteBarrier(void);
+    VOID *v = (VOID *)FSP_ATOMIC_VOLATILE_LOAD64((__int64 volatile *)(p));
+    _ReadWriteBarrier();
+    return v;
+
+#elif defined(_M_IX86)
+    void _ReadWriteBarrier(void);
+    VOID *v = (VOID *)FSP_ATOMIC_VOLATILE_LOAD32((__int32 volatile *)(p));
+    _ReadWriteBarrier();
+    return v;
+
+#endif
+}
+static inline VOID FspAtomicStorePointer(VOID *volatile *p, VOID *v)
+{
+#if defined(_M_ARM64)
+    void __dmb(unsigned int);
+    __dmb(0xb);
+    FSP_ATOMIC_VOLATILE_STORE64((__int64 volatile *)(p), (__int64)(v));
+    __dmb(0xb);
+
+#elif defined(_M_X64) || defined(_M_IX86)
+    void *_InterlockedExchangePointer(void *volatile *, void *);
+    _InterlockedExchangePointer(p, v);
+
+#endif
+}
+
 #ifdef __cplusplus
 }
 #endif