vkd3d-common: Implement spinlock.

Signed-off-by: Hans-Kristian Arntzen <post@arntzen-software.no>

Makefile.am

@@ -73,6 +73,7 @@ libvkd3d_shader_la_SOURCES = \
 	include/private/list.h \
 	include/private/rbtree.h \
 	include/private/vkd3d_common.h \
+	include/private/vkd3d_spinlock.h \
 	include/private/vkd3d_debug.h \
 	include/private/vkd3d_memory.h \
 	include/vkd3d_shader.h \
@@ -97,6 +98,7 @@ endif
 
 libvkd3d_la_SOURCES = \
 	include/private/vkd3d_common.h \
+	include/private/vkd3d_spinlock.h \
 	include/private/vkd3d_debug.h \
 	include/private/vkd3d_memory.h \
 	include/private/vkd3d_utf8.h \

include/private/vkd3d_common.h

@@ -21,6 +21,7 @@
 
 #include "config.h"
 #include "vkd3d_windows.h"
+#include "vkd3d_spinlock.h"
 
 #include <ctype.h>
 #include <stdint.h>

include/private/vkd3d_spinlock.h

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2020 Philip Rebohle for Valve Corporation
+ * Copyright 2020 Hans-Kristian Arntzen for Valve Corporation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#ifndef __VKD3D_SPINLOCK_H
+#define __VKD3D_SPINLOCK_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#if (__STDC_VERSION__ >= 201112L) && !defined(__STDC_NO_ATOMICS__)
+#include <stdatomic.h>
+
+#elif defined(__GNUC__) && ((__GNUC__ * 1000 + __GNUC_MINOR__) >= 4007)
+
+/* Can use GCC's intrinsic versions of C11 atomics. */
+#define atomic_load_explicit(lock, order) __atomic_load_n(lock, order)
+#define atomic_store_explicit(lock, value, order) __atomic_store_n(lock, value, order)
+#define atomic_exchange_explicit(lock, value, order) __atomic_exchange_n(lock, value, order)
+#define memory_order_relaxed __ATOMIC_RELAXED
+#define memory_order_acquire __ATOMIC_ACQUIRE
+#define memory_order_release __ATOMIC_RELEASE
+
+#elif defined(__GNUC__)
+/* Legacy GCC intrinsics */
+#define atomic_try_lock(lock) !__sync_lock_test_and_set(lock, 1)
+#define atomic_unlock(lock) __sync_lock_release(lock)
+
+#elif defined(_MSC_VER)
+#include <intrin.h>
+#define atomic_try_lock(lock) !InterlockedExchange(lock, 1)
+/* There is no "unlock" equivalent on MSVC, but exchange without consuming the result
+ * is effectively an unlock with correct memory semantics.
+ * Compiler is be free to optimize this. */
+#define atomic_unlock(lock) InterlockedExchange(lock, 0)
+#else
+#error "No possible spinlock implementation for this platform."
+#endif
+
+/* Generic C11 implementations of try_lock and unlock. */
+#ifndef atomic_try_lock
+#define atomic_try_lock(lock) \
+    (!atomic_load_explicit(lock, memory_order_relaxed) && \
+     !atomic_exchange_explicit(lock, 1u, memory_order_acquire))
+#endif
+
+#ifndef atomic_unlock
+#define atomic_unlock(lock) atomic_store_explicit(lock, 0u, memory_order_release)
+#endif
+
+#ifdef _MSC_VER
+typedef LONG spinlock_t;
+#else
+typedef uint32_t spinlock_t;
+#endif
+
+static inline void spinlock_init(spinlock_t *lock)
+{
+    *lock = 0;
+}
+
+static inline bool spinlock_try_acquire(spinlock_t *lock)
+{
+    return atomic_try_lock(lock);
+}
+
+static inline void spinlock_acquire(spinlock_t *lock)
+{
+    while (!spinlock_try_acquire(lock))
+        continue;
+}
+
+static inline void spinlock_release(spinlock_t *lock)
+{
+    atomic_unlock(lock);
+}
+
+#endif