9 files changed, 104 insertions, 79 deletions

diff --git a/audio/out/ao_wasapi.c b/audio/out/ao_wasapi.c
index 3d59554dcd..431b24c3a1 100644
--- a/audio/out/ao_wasapi.c
+++ b/audio/out/ao_wasapi.c
@@ -33,7 +33,6 @@
 #include "audio/out/ao_wasapi_utils.h"
 
 #include "audio/format.h"
-#include "compat/atomics.h"
 #include "osdep/timer.h"
 #include "osdep/io.h"
 
@@ -43,7 +42,7 @@
               do { if ((unk) != NULL) { release; (unk) = NULL; } } while(0)
 
 static double get_device_delay(struct wasapi_state *state) {
-    UINT64 sample_count = state->sample_count;
+    UINT64 sample_count = atomic_load(&state->sample_count);
     UINT64 position, qpc_position;
     HRESULT hr;
 
@@ -100,8 +99,7 @@ static void thread_feed(struct ao *ao)
                                           frame_count, 0);
     EXIT_ON_ERROR(hr);
 
-    mp_atomic_add_and_fetch(&state->sample_count, frame_count);
-    mp_memory_barrier();
+    atomic_fetch_add(&state->sample_count, frame_count);
 
     return;
 exit_label:
@@ -318,8 +316,7 @@ static void audio_pause(struct ao *ao)
 
     IAudioClient_Stop(state->pAudioClientProxy);
     IAudioClient_Reset(state->pAudioClientProxy);
-    state->sample_count = 0;
-    mp_memory_barrier();
+    atomic_store(&state->sample_count, 0);
 }
 
 static void audio_resume(struct ao *ao)
diff --git a/audio/out/ao_wasapi.h b/audio/out/ao_wasapi.h
index 4fe80a6c8f..52813b586d 100755
--- a/audio/out/ao_wasapi.h
+++ b/audio/out/ao_wasapi.h
@@ -28,6 +28,8 @@
 #include <mmdeviceapi.h>
 #include <avrt.h>
 
+#include "compat/atomics.h"
+
 typedef struct wasapi_state {
     struct mp_log *log;
     HANDLE threadLoop;
@@ -85,7 +87,7 @@ typedef struct wasapi_state {
     /* WASAPI internal clock information, for estimating delay */
     IAudioClock *pAudioClock;
     UINT64 clock_frequency; /* scale for the "samples" returned by the clock */
-    UINT64 sample_count; /* the amount of samples per channel written to a GetBuffer buffer */
+    atomic_ullong sample_count; /* the amount of samples per channel written to a GetBuffer buffer */
     LARGE_INTEGER qpc_frequency; /* frequency of windows' high resolution timer */
 
     int opt_exclusive;
diff --git a/audio/out/ao_wasapi_utils.c b/audio/out/ao_wasapi_utils.c
index c81562f5f3..95d2642780 100755
--- a/audio/out/ao_wasapi_utils.c
+++ b/audio/out/ao_wasapi_utils.c
@@ -426,7 +426,7 @@ static int init_clock(struct wasapi_state *state) {
 
     QueryPerformanceFrequency(&state->qpc_frequency);
 
-    state->sample_count = 0;
+    atomic_store(&state->sample_count, 0);
 
     MP_VERBOSE(state, "IAudioClock::GetFrequency gave a frequency of %"PRIu64".\n", (uint64_t) state->clock_frequency);
 
diff --git a/audio/out/pull.c b/audio/out/pull.c
index 4b0dc6e890..71f14f38dc 100644
--- a/audio/out/pull.c
+++ b/audio/out/pull.c
@@ -45,13 +45,13 @@ struct ao_pull_state {
     struct mp_ring *buffers[MP_NUM_CHANNELS];
 
     // AO_STATE_*
-    int state;
+    atomic_int state;
 
     // Whether buffers[] can be accessed.
-    int ready;
+    atomic_bool ready;
 
     // Device delay of the last written sample, in realtime.
-    int64_t end_time_us;
+    atomic_llong end_time_us;
 };
 
 static int get_space(struct ao *ao)
@@ -77,10 +77,9 @@ static int play(struct ao *ao, void **data, int samples, int flags)
         int r = mp_ring_write(p->buffers[n], data[n], write_bytes);
         assert(r == write_bytes);
     }
-    if (p->state != AO_STATE_PLAY) {
-        p->end_time_us = 0;
-        p->state = AO_STATE_PLAY;
-        mp_memory_barrier();
+    if (atomic_load(&p->state) != AO_STATE_PLAY) {
+        atomic_store(&p->end_time_us, 0);
+        atomic_store(&p->state, AO_STATE_PLAY);
         if (ao->driver->resume)
             ao->driver->resume(ao);
     }
@@ -103,8 +102,7 @@ int ao_read_data(struct ao *ao, void **data, int samples, int64_t out_time_us)
     struct ao_pull_state *p = ao->api_priv;
     int full_bytes = samples * ao->sstride;
 
-    mp_memory_barrier();
-    if (!p->ready) {
+    if (!atomic_load(&p->ready)) {
         for (int n = 0; n < ao->num_planes; n++)
             af_fill_silence(data[n], full_bytes, ao->format);
         return 0;
@@ -116,10 +114,9 @@ int ao_read_data(struct ao *ao, void **data, int samples, int64_t out_time_us)
     int bytes = MPMIN(buffered_bytes, full_bytes);
 
     if (bytes > 0)
-        p->end_time_us = out_time_us;
+        atomic_store(&p->end_time_us, out_time_us);
 
-    mp_memory_barrier();
-    if (p->state == AO_STATE_PAUSE)
+    if (atomic_load(&p->state) == AO_STATE_PAUSE)
         bytes = 0;
 
     for (int n = 0; n < ao->num_planes; n++) {
@@ -154,8 +151,7 @@ static float get_delay(struct ao *ao)
 {
     struct ao_pull_state *p = ao->api_priv;
 
-    mp_memory_barrier();
-    int64_t end = p->end_time_us;
+    int64_t end = atomic_load(&p->end_time_us);
     int64_t now = mp_time_us();
     double driver_delay = MPMAX(0, (end - now) / (1000.0 * 1000.0));
     return mp_ring_buffered(p->buffers[0]) / (double)ao->bps + driver_delay;
@@ -168,15 +164,12 @@ static void reset(struct ao *ao)
         ao->driver->reset(ao);
     // Not like this is race-condition free. It will work if ->reset
     // stops the audio callback, though.
-    p->ready = 0;
-    p->state = AO_STATE_NONE;
-    mp_memory_barrier();
+    atomic_store(&p->ready, false);
+    atomic_store(&p->state, AO_STATE_NONE);
     for (int n = 0; n < ao->num_planes; n++)
         mp_ring_reset(p->buffers[n]);
-    p->end_time_us = 0;
-    mp_memory_barrier();
-    p->ready = 1;
-    mp_memory_barrier();
+    atomic_store(&p->end_time_us, 0);
+    atomic_store(&p->ready, true);
 }
 
 static void pause(struct ao *ao)
@@ -184,15 +177,13 @@ static void pause(struct ao *ao)
     struct ao_pull_state *p = ao->api_priv;
     if (ao->driver->pause)
         ao->driver->pause(ao);
-    p->state = AO_STATE_PAUSE;
-    mp_memory_barrier();
+    atomic_store(&p->state, AO_STATE_PAUSE);
 }
 
 static void resume(struct ao *ao)
 {
     struct ao_pull_state *p = ao->api_priv;
-    p->state = AO_STATE_PLAY;
-    mp_memory_barrier();
+    atomic_store(&p->state, AO_STATE_PLAY);
     if (ao->driver->resume)
         ao->driver->resume(ao);
 }
@@ -207,8 +198,7 @@ static int init(struct ao *ao)
     struct ao_pull_state *p = ao->api_priv;
     for (int n = 0; n < ao->num_planes; n++)
             p->buffers[n] = mp_ring_new(ao, ao->buffer * ao->sstride);
-    p->ready = 1;
-    mp_memory_barrier();
+    atomic_store(&p->ready, true);
     return 0;
 }
 
diff --git a/common/msg.c b/common/msg.c
index 11fee518d2..d2e728b585 100644
--- a/common/msg.c
+++ b/common/msg.c
@@ -66,7 +66,7 @@ struct mp_log_root {
     /* This is incremented every time the msglevels must be reloaded.
      * (This is perhaps better than maintaining a globally accessible and
      * synchronized mp_log tree.) */
-    int64_t reload_counter;
+    atomic_ulong reload_counter;
 };
 
 struct mp_log {
@@ -75,7 +75,7 @@ struct mp_log {
     const char *verbose_prefix;
     int level;                  // minimum log level for any outputs
     int terminal_level;         // minimum log level for terminal output
-    int64_t reload_counter;
+    atomic_ulong reload_counter;
 };
 
 struct mp_log_buffer {
@@ -119,7 +119,7 @@ static void update_loglevel(struct mp_log *log)
         log->level = MPMAX(log->level, log->root->buffers[n]->level);
     if (log->root->stats_file)
         log->level = MPMAX(log->level, MSGL_STATS);
-    log->reload_counter = log->root->reload_counter;
+    atomic_store(&log->reload_counter, atomic_load(&log->root->reload_counter));
     pthread_mutex_unlock(&mp_msg_lock);
 }
 
@@ -127,10 +127,10 @@ static void update_loglevel(struct mp_log *log)
 // Thread-safety: see mp_msg().
 bool mp_msg_test(struct mp_log *log, int lev)
 {
-    mp_memory_barrier();
-    if (!log->root || log->root->mute)
+    struct mp_log_root *root = log->root;
+    if (!root || root->mute)
         return false;
-    if (log->reload_counter != log->root->reload_counter)
+    if (atomic_load(&log->reload_counter) != atomic_load(&root->reload_counter))
         update_loglevel(log);
     return lev <= log->level;
 }
@@ -395,9 +395,11 @@ void mp_msg_init(struct mpv_global *global)
     assert(!global->log);
 
     struct mp_log_root *root = talloc_zero(NULL, struct mp_log_root);
-    root->global = global;
-    root->header = true;
-    root->reload_counter = 1;
+    *root = (struct mp_log_root){
+        .global = global,
+        .header = true,
+        .reload_counter = ATOMIC_VAR_INIT(1),
+    };
 
     struct mp_log dummy = { .root = root };
     struct mp_log *log = mp_log_new(root, &dummy, "");
@@ -429,8 +431,7 @@ void mp_msg_update_msglevels(struct mpv_global *global)
     talloc_free(root->msglevels);
     root->msglevels = talloc_strdup(root, global->opts->msglevels);
 
-    mp_atomic_add_and_fetch(&root->reload_counter, 1);
-    mp_memory_barrier();
+    atomic_fetch_add(&root->reload_counter, 1);
     pthread_mutex_unlock(&mp_msg_lock);
 }
 
@@ -475,9 +476,7 @@ struct mp_log_buffer *mp_msg_log_buffer_new(struct mpv_global *global,
 
     MP_TARRAY_APPEND(root, root->buffers, root->num_buffers, buffer);
 
-    mp_atomic_add_and_fetch(&root->reload_counter, 1);
-    mp_memory_barrier();
-
+    atomic_fetch_add(&root->reload_counter, 1);
     pthread_mutex_unlock(&mp_msg_lock);
 
     return buffer;
@@ -510,9 +509,7 @@ found:
     }
     talloc_free(buffer);
 
-    mp_atomic_add_and_fetch(&root->reload_counter, 1);
-    mp_memory_barrier();
-
+    atomic_fetch_add(&root->reload_counter, 1);
     pthread_mutex_unlock(&mp_msg_lock);
 }
 
diff --git a/compat/atomics.h b/compat/atomics.h
index 14f0f2720f..56328ab354 100644
--- a/compat/atomics.h
+++ b/compat/atomics.h
@@ -16,17 +16,47 @@
  * with mpv.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-// At this point both gcc and clang had __sync_synchronize support for some
-// time. We only support a full memory barrier.
+#ifndef MP_ATOMICS_H
+#define MP_ATOMICS_H
 
+#include <inttypes.h>
 #include "config.h"
 
+#if HAVE_STDATOMIC
+#include <stdatomic.h>
+#else
+
+// Emulate the parts of C11 stdatomic.h needed by mpv.
+// Still relies on gcc/clang atomic builtins.
+
+typedef struct { volatile unsigned long v;  } atomic_ulong;
+typedef struct { volatile int v;            } atomic_int;
+typedef struct { volatile _Bool v;          } atomic_bool;
+typedef struct { volatile long long v;      } atomic_llong;
+typedef struct { volatile uint_least32_t v; } atomic_uint_least32_t;
+typedef struct { volatile unsigned long long v; } atomic_ullong;
+
+#define ATOMIC_VAR_INIT(x) \
+    {.v = (x)}
+#define atomic_load(p) \
+    (mp_memory_barrier(), (p)->v)
+#define atomic_store(p, val) \
+    ((p)->v = (val), mp_memory_barrier())
+
 #if HAVE_ATOMIC_BUILTINS
-# define mp_memory_barrier()           __atomic_thread_fence(__ATOMIC_SEQ_CST)
-# define mp_atomic_add_and_fetch(a, b) __atomic_add_fetch(a, b,__ATOMIC_SEQ_CST)
+# define mp_memory_barrier() \
+    __atomic_thread_fence(__ATOMIC_SEQ_CST)
+# define atomic_fetch_add(a, b) \
+    __atomic_add_fetch(&(a)->v, b, __ATOMIC_SEQ_CST)
 #elif HAVE_SYNC_BUILTINS
-# define mp_memory_barrier()           __sync_synchronize()
-# define mp_atomic_add_and_fetch(a, b) __sync_add_and_fetch(a, b)
+# define mp_memory_barrier() \
+    __sync_synchronize()
+# define atomic_fetch_add(a, b) \
+    (__sync_add_and_fetch(&(a)->v, b), mp_memory_barrier())
 #else
 # error "this should have been a configuration error, report a bug please"
 #endif
+
+#endif /* else HAVE_STDATOMIC */
+
+#endif
diff --git a/misc/ring.c b/misc/ring.c
index eb139c2cab..28e610c9bb 100644
--- a/misc/ring.c
+++ b/misc/ring.c
@@ -30,19 +30,17 @@ struct mp_ring {
     /* Positions of the first readable/writeable chunks. Do not read this
      * fields but use the atomic private accessors `mp_ring_get_wpos`
      * and `mp_ring_get_rpos`. */
-    uint32_t rpos, wpos;
+    atomic_uint_least32_t rpos, wpos;
 };
 
 static uint32_t mp_ring_get_wpos(struct mp_ring *buffer)
 {
-    mp_memory_barrier();
-    return buffer->wpos;
+    return atomic_load(&buffer->wpos);
 }
 
 static uint32_t mp_ring_get_rpos(struct mp_ring *buffer)
 {
-    mp_memory_barrier();
-    return buffer->rpos;
+    return atomic_load(&buffer->rpos);
 }
 
 struct mp_ring *mp_ring_new(void *talloc_ctx, int size)
@@ -61,8 +59,7 @@ int mp_ring_drain(struct mp_ring *buffer, int len)
 {
     int buffered  = mp_ring_buffered(buffer);
     int drain_len = FFMIN(len, buffered);
-    mp_atomic_add_and_fetch(&buffer->rpos, drain_len);
-    mp_memory_barrier();
+    atomic_fetch_add(&buffer->rpos, drain_len);
     return drain_len;
 }
 
@@ -81,8 +78,7 @@ int mp_ring_read(struct mp_ring *buffer, unsigned char *dest, int len)
     memcpy(dest, buffer->buffer + read_ptr, len1);
     memcpy(dest + len1, buffer->buffer, len2);
 
-    mp_atomic_add_and_fetch(&buffer->rpos, read_len);
-    mp_memory_barrier();
+    atomic_fetch_add(&buffer->rpos, read_len);
 
     return read_len;
 }
@@ -100,16 +96,15 @@ int mp_ring_write(struct mp_ring *buffer, unsigned char *src, int len)
     memcpy(buffer->buffer + write_ptr, src, len1);
     memcpy(buffer->buffer, src + len1, len2);
 
-    mp_atomic_add_and_fetch(&buffer->wpos, write_len);
-    mp_memory_barrier();
+    atomic_fetch_add(&buffer->wpos, write_len);
 
     return write_len;
 }
 
 void mp_ring_reset(struct mp_ring *buffer)
 {
-    buffer->wpos = buffer->rpos = 0;
-    mp_memory_barrier();
+    atomic_store(&buffer->wpos, 0);
+    atomic_store(&buffer->rpos, 0);
 }
 
 int mp_ring_available(struct mp_ring *buffer)
diff --git a/old-configure b/old-configure
index 819676ed6b..03ee0a5eb8 100755
--- a/old-configure
+++ b/old-configure
@@ -268,7 +268,7 @@ exit 0
 # If autodetection is available then the third state is: auto
 _pkg_config=auto
 _cc=auto
-test "$CC" && _cc="$CC"
+test -n "$CC" && _cc="$CC"
 _opt=-O2
 _prefix="/usr/local"
 options_state_machine init
@@ -485,19 +485,25 @@ extra_cflags="$extra_cflags -D_REENTRANT -D_THREAD_SAFE"
 compile_check waftools/fragments/pthreads.c "$_ld_pthread" || die "Unable to find pthreads support."
 echores "yes"
 
-check_statement_libs "compiler support for __atomic built-ins" auto ATOMIC_BUILTINS \
+check_statement_libs "support for stdatomic.h" auto STDATOMIC \
+    stdatomic.h '_Atomic int test = ATOMIC_VAR_INIT(123); int test2 = atomic_load(&test)'
+_stdatomic=$(defretval)
+
+_atomic=auto
+test "$_stdatomic" = yes && _atomic=no
+check_statement_libs "compiler support for __atomic built-ins" $_atomic ATOMIC_BUILTINS \
     stdint.h 'int64_t test = 0; test = __atomic_add_fetch(&test, 1, __ATOMIC_SEQ_CST)' \
     " " "-latomic"
 _atomic=$(defretval)
 
 _sync=auto
-test "$_atomic" = yes && _sync=no
+(test "$_atomic" = yes || test "$_stdatomic" = yes ) && _sync=no
 check_statement_libs "compiler support for __sync built-ins" $_sync SYNC_BUILTINS \
     stdint.h 'int64_t test = 0; test = __sync_add_and_fetch(&test, 1)'
 _sync=$(defretval)
 
-if test "$_atomic" = no && test "$_sync" = no ; then
-  die "your compiler must support either __atomic or __sync built-ins."
+if test "$_atomic" = no && test "$_sync" = no && test "$_stdatomic" = no ; then
+  die "your compiler must support either stdatomic.h, or __atomic, or __sync built-ins."
 fi
 
 check_compile "iconv" $_iconv ICONV waftools/fragments/iconv.c " " "-liconv" "-liconv $_ld_dl"
diff --git a/wscript b/wscript
index 796c0819bf..be900c03f7 100644
--- a/wscript
+++ b/wscript
@@ -105,24 +105,32 @@ main_dependencies = [
         'req': True,
         'fmsg': 'Unable to find pthreads support.'
     }, {
+        'name': 'stdatomic',
+        'desc': 'stdatomic.h',
+        'func':
+            check_statement('stdatomic.h',
+                '_Atomic int test = ATOMIC_VAR_INIT(123);'
+                'int test2 = atomic_load(&test)')
+    }, {
         'name': 'atomic-builtins',
         'desc': 'compiler support for __atomic built-ins',
         'func': check_libs(['atomic'],
             check_statement('stdint.h',
                 'int64_t test = 0;'
-                'test = __atomic_add_fetch(&test, 1, __ATOMIC_SEQ_CST)'))
+                'test = __atomic_add_fetch(&test, 1, __ATOMIC_SEQ_CST)')),
+        'deps_neg': [ 'stdatomic' ],
     }, {
         'name': 'sync-builtins',
         'desc': 'compiler support for __sync built-ins',
         'func': check_statement('stdint.h',
                     'int64_t test = 0;'
                     'test = __sync_add_and_fetch(&test, 1)'),
-        'deps_neg': [ 'atomic-builtins' ],
+        'deps_neg': [ 'stdatomic', 'atomic-builtins' ],
     }, {
         'name': 'thread-synchronization-builtins',
         'desc': 'compiler support for usable thread synchronization built-ins',
         'func': check_true,
-        'deps_any': ['atomic-builtins', 'sync-builtins'],
+        'deps_any': ['stdatomic', 'atomic-builtins', 'sync-builtins'],
         'req': True,
         'fmsg': 'your compiler must support either __atomic or __sync built-ins',
     }, {