[FFmpeg-devel] [PATCH 2/3] avutil/atomic: Add avpriv_atomic_int64_cas()

[Michael Niedermayer]

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavutil/atomic.c     | 20 ++++++++++++++++++++
 libavutil/atomic.h     | 10 ++++++++++
 libavutil/atomic_gcc.h | 12 ++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/libavutil/atomic.c b/libavutil/atomic.c
index 64cff25..27561ad 100644
--- a/libavutil/atomic.c
+++ b/libavutil/atomic.c
@@ -70,6 +70,17 @@ void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
     return ret;
 }
 
+int64_t avpriv_atomic_int64_cas(int64_t volatile *ptr, int64_t oldval, int64_t newval)
+{
+    int64_t ret;
+    pthread_mutex_lock(&atomic_lock);
+    ret = *ptr;
+    if (ret == oldval)
+        *ptr = newval;
+    pthread_mutex_unlock(&atomic_lock);
+    return ret;
+}
+
 #elif !HAVE_THREADS
 
 int avpriv_atomic_int_get(volatile int *ptr)
@@ -97,6 +108,15 @@ void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval)
     return *ptr;
 }
 
+int64_t avpriv_atomic_int64_cas(int64_t volatile *ptr, int64_t oldval, int64_t newval)
+{
+    if (*ptr == oldval) {
+        *ptr = newval;
+        return oldval;
+    }
+    return *ptr;
+}
+
 #else /* HAVE_THREADS */
 
 /* This should never trigger, unless a new threading implementation
diff --git a/libavutil/atomic.h b/libavutil/atomic.h
index 15906d2..cabc4f0 100644
--- a/libavutil/atomic.h
+++ b/libavutil/atomic.h
@@ -74,6 +74,16 @@ int avpriv_atomic_int_add_and_fetch(volatile int *ptr, int inc);
  */
 void *avpriv_atomic_ptr_cas(void * volatile *ptr, void *oldval, void *newval);
 
+/**
+ * Atomic int64_t compare and swap.
+ *
+ * @param ptr pointer to the int64_t to operate on
+ * @param oldval do the swap if the current value of *ptr equals to oldval
+ * @param newval value to replace *ptr with
+ * @return the value of *ptr before comparison
+ */
+int64_t avpriv_atomic_int64_cas(int64_t volatile *ptr, int64_t oldval, int64_t newval);
+
 #endif /* HAVE_ATOMICS_NATIVE */
 
 #endif /* AVUTIL_ATOMIC_H */
diff --git a/libavutil/atomic_gcc.h b/libavutil/atomic_gcc.h
index 5f9fc49..c7e0dba 100644
--- a/libavutil/atomic_gcc.h
+++ b/libavutil/atomic_gcc.h
@@ -75,4 +75,16 @@ static inline void *atomic_ptr_cas_gcc(void * volatile *ptr,
 #endif
 }
 
+#define avpriv_atomic_int64_cas atomic_int64_cas_gcc
+static inline int64_t atomic_int64_cas_gcc(int64_t volatile *ptr,
+                                           int64_t oldval, int64_t newval)
+{
+#if HAVE_SYNC_VAL_COMPARE_AND_SWAP
+    return __sync_val_compare_and_swap(ptr, oldval, newval);
+#else
+    __atomic_compare_exchange_n(ptr, &oldval, newval, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+    return oldval;
+#endif
+}
+
 #endif /* AVUTIL_ATOMIC_GCC_H */
-- 
2.10.2