3 files changed, 82 insertions, 1 deletions
diff --git a/include/compat/stdatomic.h b/include/compat/stdatomic.h
new file mode 100644
index 0000000..28fe40c
--- /dev/null
+++ b/include/compat/stdatomic.h
@@ -0,0 +1,70 @@
+/*
+* Copyright © 2018, VideoLAN and dav1d authors
+* All rights reserved.
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions are met:
+*
+* 1. Redistributions of source code must retain the above copyright notice, this
+*    list of conditions and the following disclaimer.
+*
+* 2. Redistributions in binary form must reproduce the above copyright notice,
+*    this list of conditions and the following disclaimer in the documentation
+*    and/or other materials provided with the distribution.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef MSCVER_STDATOMIC_H_
+#define MSCVER_STDATOMIC_H_
+
+#if !defined(__cplusplus) && defined(_MSC_VER)
+
+#pragma warning(push)
+#pragma warning(disable:4067)    /* newline for __has_include_next */
+
+#if defined(__clang__) && __has_include_next(<stdatomic.h>)
+   /* use the clang stdatomic.h with clang-cl*/
+#  include_next <stdatomic.h>
+#else /* ! stdatomic.h */
+
+#include <windows.h>
+
+#include "common/attributes.h"
+
+typedef volatile LONG  __declspec(align(32)) atomic_int;
+typedef volatile ULONG __declspec(align(32)) atomic_uint;
+
+typedef enum {
+    memory_order_relaxed,
+    memory_order_acquire
+} msvc_atomic_memory_order;
+
+#define atomic_init(p_a, v)           do { *(p_a) = (v); } while(0)
+#define atomic_store(p_a, v)          InterlockedExchange((LONG*)p_a, v)
+#define atomic_load(p_a)              InterlockedCompareExchange((LONG*)p_a, 0, 0)
+#define atomic_load_explicit(p_a, mo) atomic_load(p_a)
+
+/*
+ * TODO use a special call to increment/decrement
+ * using InterlockedIncrement/InterlockedDecrement
+ */
+#define atomic_fetch_add(p_a, inc)    InterlockedExchangeAdd(p_a, inc)
+#define atomic_fetch_sub(p_a, dec)    InterlockedExchangeAdd(p_a, -(dec))
+
+#endif /* ! stdatomic.h */
+
+#pragma warning(pop)
+
+#endif /* !defined(__cplusplus) && defined(_MSC_VER) */
+
+#endif /* MSCVER_STDATOMIC_H_ */
diff --git a/meson.build b/meson.build
index 07e02d1..1d47dfa 100644
--- a/meson.build
+++ b/meson.build
@@ -92,8 +92,16 @@ endif
 
 # Header checks
 
+stdatomic_dependency = []
 if not cc.check_header('stdatomic.h')
-    error('Atomics not supported')
+    if cc.get_id() == 'msvc'
+        # we have a custom replacement for MSVC
+        stdatomic_dependency = declare_dependency(
+            include_directories : include_directories('include/compat'),
+        )
+    else
+        error('Atomics not supported')
+    endif
 endif
 
 if cc.check_header('unistd.h')
diff --git a/src/meson.build b/src/meson.build
index a574889..577dc23 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -134,6 +134,7 @@ libdav1d_entrypoints_objs = static_library('dav1d_entrypoint',
     rev_target,
 
     include_directories : dav1d_inc_dirs,
+    dependencies: [stdatomic_dependency],
     c_args : stackrealign_flag,
     install : false,
     build_by_default : false,
@@ -146,6 +147,7 @@ foreach bitdepth : dav1d_bitdepths
         'dav1d_bitdepth_@0@'.format(bitdepth),
         libdav1d_tmpl_sources, config_h_target,
         include_directories: dav1d_inc_dirs,
+        dependencies : [stdatomic_dependency],
         c_args : ['-DBITDEPTH=@0@'.format(bitdepth)] + stackalign_flag,
         install : false,
         build_by_default : false,
@@ -166,6 +168,7 @@ libdav1d_private = static_library('dav1d_private',
         ],
 
     include_directories : dav1d_inc_dirs,
+    dependencies : [stdatomic_dependency],
     c_args : [stackalign_flag],
     install : false,
     build_by_default : false,