diff mbox

[FFmpeg-devel,1/4] Add a compat stdatomic.h implementation based on windows atomics

Message ID 1480375796-28595-1-git-send-email-wtc@google.com
State Accepted
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Commit Message

Wan-Teh Chang Nov. 28, 2016, 11:29 p.m. UTC
From: Anton Khirnov <anton@khirnov.net>

Adapted from the code by Rémi Denis-Courmont from VLC

This merges libav commit c2755864afadfbaa349e8d583665c86fe99fa90b.

Signed-off-by: Wan-Teh Chang <wtc@google.com>
---
 compat/atomics/win32/stdatomic.h | 179 +++++++++++++++++++++++++++++++++++++++
 configure                        |   2 +
 2 files changed, 181 insertions(+)
 create mode 100644 compat/atomics/win32/stdatomic.h

Comments

wm4 Nov. 29, 2016, 12:12 p.m. UTC | #1
On Mon, 28 Nov 2016 15:29:53 -0800
Wan-Teh Chang <wtc-at-google.com@ffmpeg.org> wrote:

> From: Anton Khirnov <anton@khirnov.net>
> 
> Adapted from the code by Rémi Denis-Courmont from VLC
> 
> This merges libav commit c2755864afadfbaa349e8d583665c86fe99fa90b.
> 
> Signed-off-by: Wan-Teh Chang <wtc@google.com>
> ---

Patchset seems ok. No changes to the actual ffmpeg code yet. I assume
the patches are unchanged from Libav.
Carl Eugen Hoyos Nov. 29, 2016, 2:46 p.m. UTC | #2
2016-11-29 0:29 GMT+01:00 Wan-Teh Chang <wtc-at-google.com@ffmpeg.org>:

> Adapted from the code by Rémi Denis-Courmont from VLC

Missing copyright statement, please do not commit as-is!

Carl Eugen
Wan-Teh Chang Nov. 29, 2016, 3:55 p.m. UTC | #3
On Tue, Nov 29, 2016 at 6:46 AM, Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote:
> 2016-11-29 0:29 GMT+01:00 Wan-Teh Chang <wtc-at-google.com@ffmpeg.org>:
>
>> Adapted from the code by Rémi Denis-Courmont from VLC
>
> Missing copyright statement, please do not commit as-is!

Hi Carl,

I made only the following changes to the Libav commits:

1. I changed Libav's LGPL license header to FFmpeg's LGPL license header.

2. I changed the header inclusion guard macros (from
LIBAV_COMPAT_ATOMICS_..._STDATOMIC_H to
COMPAT_ATOMICS_..._STDATOMIC_H).

Rémi Denis-Courmont's copyright notice is not in all the headers I
copied from Libav. I can do some source code archaeology in the VLC
source code repository.

Wan-Teh Chang
wm4 Nov. 29, 2016, 4:09 p.m. UTC | #4
On Tue, 29 Nov 2016 07:55:18 -0800
Wan-Teh Chang <wtc-at-google.com@ffmpeg.org> wrote:

> On Tue, Nov 29, 2016 at 6:46 AM, Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote:
> > 2016-11-29 0:29 GMT+01:00 Wan-Teh Chang <wtc-at-google.com@ffmpeg.org>:
> >  
> >> Adapted from the code by Rémi Denis-Courmont from VLC  
> >
> > Missing copyright statement, please do not commit as-is!  
> 
> Hi Carl,
> 
> I made only the following changes to the Libav commits:
> 
> 1. I changed Libav's LGPL license header to FFmpeg's LGPL license header.
> 
> 2. I changed the header inclusion guard macros (from
> LIBAV_COMPAT_ATOMICS_..._STDATOMIC_H to
> COMPAT_ATOMICS_..._STDATOMIC_H).
> 
> Rémi Denis-Courmont's copyright notice is not in all the headers I
> copied from Libav. I can do some source code archaeology in the VLC
> source code repository.

I don't think that's required anyway.
Wan-Teh Chang Nov. 29, 2016, 5:53 p.m. UTC | #5
I studied the history of vlc/include/vlc_atomic.h and compared it wth
libav/compat/atomics/win32/stdatomic.h.

1. vlc/include/vlc_atomic.h was initially written by Rémi
Denis-Courmont. This is the most substantial commit by Rémi
Denis-Courmont:

http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=ad3586579f956b6856d2f7c0c4cbd860fd8241af

2. The Windows port was written by Felix Abecassis. Note that he
didn't add his copyright notice to vlc/include/vlc_atomic.h. This is
the most substantial commit by Felix Abecassis:

http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=9c077c0d28df2ad7387b4db8702bd023b2556c86

3. libav/compat/atomics/win32/stdatomic.h contains code that is
apparently derived from the code in vlc/include/vlc_atomic.h written
by both Rémi Denis-Courmont and Felix Abecassis, but doesn't have a
copyright notice.

Similarly, libav/compat/atomics/suncc/stdatomic.h contains code that
is apparently derived from the code in vlc/include/vlc_atomic.h
written by Rémi Denis-Courmont, but doesn't have a copyright notice.

4. Given this information, should I add a copyright notice to
ffmpeg/compat/atomics/win32/stdatomic.h and
ffmpeg/compat/atomics/suncc/stdatomic.h?

5. A related question: libav/compat/atomics/pthread/stdatomic.c does
NOT contain any code that is apparently derived from the code in
vlc/include/vlc_atomic.h written by Rémi Denis-Courmont, but
libav/compat/atomics/pthread/stdatomic.c contains a copyright notice
of Rémi Denis-Courmont. Should I remove that copyright notice from
ffmpeg/compat/atomics/pthread/stdatomic.c?

Thanks,
Wan-Teh Chang
James Almer Dec. 2, 2016, 7:48 p.m. UTC | #6
On 11/29/2016 9:12 AM, wm4 wrote:
> On Mon, 28 Nov 2016 15:29:53 -0800
> Wan-Teh Chang <wtc-at-google.com@ffmpeg.org> wrote:
> 
>> From: Anton Khirnov <anton@khirnov.net>
>>
>> Adapted from the code by Rémi Denis-Courmont from VLC
>>
>> This merges libav commit c2755864afadfbaa349e8d583665c86fe99fa90b.
>>
>> Signed-off-by: Wan-Teh Chang <wtc@google.com>
>> ---
> 
> Patchset seems ok. No changes to the actual ffmpeg code yet. I assume
> the patches are unchanged from Libav.

Patchset applied.
diff mbox

Patch

diff --git a/compat/atomics/win32/stdatomic.h b/compat/atomics/win32/stdatomic.h
new file mode 100644
index 0000000..4cbba9c
--- /dev/null
+++ b/compat/atomics/win32/stdatomic.h
@@ -0,0 +1,179 @@ 
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef COMPAT_ATOMICS_WIN32_STDATOMIC_H
+#define COMPAT_ATOMICS_WIN32_STDATOMIC_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <windows.h>
+
+#define ATOMIC_FLAG_INIT 0
+
+#define ATOMIC_VAR_INIT(value) (value)
+
+#define atomic_init(obj, value) \
+do {                            \
+    *(obj) = (value);           \
+} while(0)
+
+#define kill_dependency(y) ((void)0)
+
+#define atomic_thread_fence(order) \
+    MemoryBarrier();
+
+#define atomic_signal_fence(order) \
+    ((void)0)
+
+#define atomic_is_lock_free(obj) 0
+
+typedef intptr_t atomic_flag;
+typedef intptr_t atomic_bool;
+typedef intptr_t atomic_char;
+typedef intptr_t atomic_schar;
+typedef intptr_t atomic_uchar;
+typedef intptr_t atomic_short;
+typedef intptr_t atomic_ushort;
+typedef intptr_t atomic_int;
+typedef intptr_t atomic_uint;
+typedef intptr_t atomic_long;
+typedef intptr_t atomic_ulong;
+typedef intptr_t atomic_llong;
+typedef intptr_t atomic_ullong;
+typedef intptr_t atomic_wchar_t;
+typedef intptr_t atomic_int_least8_t;
+typedef intptr_t atomic_uint_least8_t;
+typedef intptr_t atomic_int_least16_t;
+typedef intptr_t atomic_uint_least16_t;
+typedef intptr_t atomic_int_least32_t;
+typedef intptr_t atomic_uint_least32_t;
+typedef intptr_t atomic_int_least64_t;
+typedef intptr_t atomic_uint_least64_t;
+typedef intptr_t atomic_int_fast8_t;
+typedef intptr_t atomic_uint_fast8_t;
+typedef intptr_t atomic_int_fast16_t;
+typedef intptr_t atomic_uint_fast16_t;
+typedef intptr_t atomic_int_fast32_t;
+typedef intptr_t atomic_uint_fast32_t;
+typedef intptr_t atomic_int_fast64_t;
+typedef intptr_t atomic_uint_fast64_t;
+typedef intptr_t atomic_intptr_t;
+typedef intptr_t atomic_uintptr_t;
+typedef intptr_t atomic_size_t;
+typedef intptr_t atomic_ptrdiff_t;
+typedef intptr_t atomic_intmax_t;
+typedef intptr_t atomic_uintmax_t;
+
+#define atomic_store(object, desired)   \
+do {                                    \
+    *(object) = (desired);              \
+    MemoryBarrier();                    \
+} while (0)
+
+#define atomic_store_explicit(object, desired, order) \
+    atomic_store(object, desired)
+
+#define atomic_load(object) \
+    (MemoryBarrier(), *(object))
+
+#define atomic_load_explicit(object, order) \
+    atomic_load(object)
+
+#define atomic_exchange(object, desired) \
+    InterlockedExchangePointer(object, desired);
+
+#define atomic_exchange_explicit(object, desired, order) \
+    atomic_exchange(object, desired)
+
+static inline int atomic_compare_exchange_strong(intptr_t *object, intptr_t *expected,
+                                                 intptr_t desired)
+{
+    intptr_t old = *expected;
+    *expected = InterlockedCompareExchangePointer(object, desired, old);
+    return *expected == old;
+}
+
+#define atomic_compare_exchange_strong_explicit(object, expected, desired, success, failure) \
+    atomic_compare_exchange_strong(object, expected, desired)
+
+#define atomic_compare_exchange_weak(object, expected, desired) \
+    atomic_compare_exchange_strong(object, expected, desired)
+
+#define atomic_compare_exchange_weak_explicit(object, expected, desired, success, failure) \
+    atomic_compare_exchange_weak(object, expected, desired)
+
+#ifdef _WIN64
+#define atomic_fetch_add(object, operand) \
+    InterlockedExchangeAdd64(object, operand)
+
+#define atomic_fetch_sub(object, operand) \
+    InterlockedExchangeAdd64(object, -(operand))
+
+#define atomic_fetch_or(object, operand) \
+    InterlockedOr64(object, operand)
+
+#define atomic_fetch_xor(object, operand) \
+    InterlockedXor64(object, operand)
+
+#define atomic_fetch_and(object, operand) \
+    InterlockedAnd64(object, operand)
+#else
+#define atomic_fetch_add(object, operand) \
+    InterlockedExchangeAdd(object, operand)
+
+#define atomic_fetch_sub(object, operand) \
+    InterlockedExchangeAdd(object, -(operand))
+
+#define atomic_fetch_or(object, operand) \
+    InterlockedOr(object, operand)
+
+#define atomic_fetch_xor(object, operand) \
+    InterlockedXor(object, operand)
+
+#define atomic_fetch_and(object, operand) \
+    InterlockedAnd(object, operand)
+#endif /* _WIN64 */
+
+#define atomic_fetch_add_explicit(object, operand, order) \
+    atomic_fetch_add(object, operand)
+
+#define atomic_fetch_sub_explicit(object, operand, order) \
+    atomic_fetch_sub(object, operand)
+
+#define atomic_fetch_or_explicit(object, operand, order) \
+    atomic_fetch_or(object, operand)
+
+#define atomic_fetch_xor_explicit(object, operand, order) \
+    atomic_fetch_sub(object, operand)
+
+#define atomic_fetch_and_explicit(object, operand, order) \
+    atomic_fetch_and(object, operand)
+
+#define atomic_flag_test_and_set(object) \
+    atomic_exchange(object, 1)
+
+#define atomic_flag_test_and_set_explicit(object, order) \
+    atomic_flag_test_and_set(object)
+
+#define atomic_flag_clear(object) \
+    atomic_store(object, 0)
+
+#define atomic_flag_clear_explicit(object, order) \
+    atomic_flag_clear(object)
+
+#endif /* COMPAT_ATOMICS_WIN32_STDATOMIC_H */
diff --git a/configure b/configure
index 8cbe6f8..2a77be9 100755
--- a/configure
+++ b/configure
@@ -6384,6 +6384,8 @@  done
 if disabled stdatomic_h; then
     if enabled atomics_gcc; then
         add_cppflags '-I\$(SRC_PATH)/compat/atomics/gcc'
+    elif enabled atomics_win32; then
+        add_cppflags '-I\$(SRC_PATH)/compat/atomics/win32'
     fi
 fi