From 3ff56f4a3c03412e9ddf0e4c60c93a3db9e6481a Mon Sep 17 00:00:00 2001
From: Ryan Pavlik <ryan.pavlik@collabora.com>
Date: Wed, 15 Jul 2020 13:01:00 -0500
Subject: [PATCH] inc/xrt: Add Windows implementations of atomic intrinsics.

---
 src/xrt/include/xrt/xrt_compiler.h | 48 ++++++++++++++++++++++++++----
 src/xrt/include/xrt/xrt_defines.h  |  6 ++--
 2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/src/xrt/include/xrt/xrt_compiler.h b/src/xrt/include/xrt/xrt_compiler.h
index 990e02d86..e80c0fc0c 100644
--- a/src/xrt/include/xrt/xrt_compiler.h
+++ b/src/xrt/include/xrt/xrt_compiler.h
@@ -17,6 +17,18 @@
 #include <stdint.h>
 #include <stdbool.h>
 
+#ifdef _MSC_VER
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif // !WIN32_LEAN_AND_MEAN
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif // !NOMINMAX
+
+#include <intrin.h>
+// for atomic intrinsics
+#include <windows.h>
+#endif // _MSC_VER
 
 /*!
  * Array size helper.
@@ -71,7 +83,6 @@
 #elif defined(__clang__) || defined(__GNUC__)
 #define XRT_DEBUGBREAK() __builtin_trap()
 #elif defined(_MSC_VER)
-#include <intrin.h>
 #define XRT_DEBUGBREAK() __debugbreak()
 #else
 #error "compiler not supported"
@@ -79,14 +90,41 @@
 
 
 
+typedef volatile int32_t xrt_atomic_s32_t;
+
+static inline int32_t
+xrt_atomic_s32_inc_return(xrt_atomic_s32_t *p)
+{
 #if defined(__GNUC__)
-#define xrt_atomic_inc_return(v) __sync_add_and_fetch((v), 1)
-#define xrt_atomic_dec_return(v) __sync_sub_and_fetch((v), 1)
-#define xrt_atomic_cmpxchg(v, old, _new)                                       \
-	__sync_val_compare_and_swap((v), (old), (_new))
+	return __sync_add_and_fetch(p, 1);
+#elif defined(_MSC_VER)
+	return InterlockedIncrement((volatile LONG *)p);
 #else
 #error "compiler not supported"
 #endif
+}
+static inline int32_t
+xrt_atomic_s32_dec_return(xrt_atomic_s32_t *p)
+{
+#if defined(__GNUC__)
+	return __sync_sub_and_fetch(p, 1);
+#elif defined(_MSC_VER)
+	return InterlockedDecrement((volatile LONG *)p);
+#else
+#error "compiler not supported"
+#endif
+}
+static inline int32_t
+xrt_atomic_s32_cmpxchg(xrt_atomic_s32_t *p, int32_t old_, int32_t new_)
+{
+#if defined(__GNUC__)
+	return __sync_val_compare_and_swap(p, old_, new_);
+#elif defined(_MSC_VER)
+	return InterlockedCompareExchange((volatile LONG *)p, old_, new_);
+#else
+#error "compiler not supported"
+#endif
+}
 
 /*!
  * Get the holder from a pointer to a field.
diff --git a/src/xrt/include/xrt/xrt_defines.h b/src/xrt/include/xrt/xrt_defines.h
index 25e3f644c..24c29185f 100644
--- a/src/xrt/include/xrt/xrt_defines.h
+++ b/src/xrt/include/xrt/xrt_defines.h
@@ -28,7 +28,7 @@ extern "C" {
  */
 struct xrt_reference
 {
-	uint32_t count;
+	xrt_atomic_s32_t count;
 };
 
 /*!
@@ -617,14 +617,14 @@ union xrt_output_value {
 static inline bool
 xrt_reference_dec(struct xrt_reference *xref)
 {
-	int count = xrt_atomic_dec_return(&xref->count);
+	int32_t count = xrt_atomic_s32_dec_return(&xref->count);
 	return count == 0;
 }
 
 static inline void
 xrt_reference_inc(struct xrt_reference *xref)
 {
-	xrt_atomic_inc_return(&xref->count);
+	xrt_atomic_s32_inc_return(&xref->count);
 }