Partial atomic replacement for antiquated GCC versions (fixes #6825)

include/vlc_atomic.h

@@ -28,9 +28,13 @@
 
 # if !defined (__cplusplus) && (__STDC_VERSION__ >= 201112L) \
   && !defined (__STDC_NO_ATOMICS__)
+
+/*** Native C11 atomics ***/
 #  include <stdatomic.h>
 
-# else /* if (???) */
+# elif defined (__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
+
+/*** Intel/GCC atomics ***/
 
 #  define ATOMIC_FLAG_INIT false
 
@@ -201,6 +205,211 @@ bool vlc_atomic_compare_exchange(volatile void *object, void *expected,
 #  define atomic_flag_clear_explicit(object,order) \
     atomic_flag_clear(object)
 
+# else
+
+/*** No atomics ***/
+
+#  define ATOMIC_FLAG_INIT false
+
+#  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) \
+    __sync_synchronize()
+
+#  define atomic_signal_fence(order) \
+    ((void)0)
+
+#  define atomic_is_lock_free(obj) \
+    false
+
+typedef uintptr_t atomic_generic_t;
+typedef atomic_generic_t atomic_flag;
+typedef atomic_generic_t atomic_bool;
+//typedef atomic_generic_t atomic_char;
+//typedef atomic_generic_t atomic_schar;
+typedef atomic_generic_t atomic_uchar;
+//typedef atomic_generic_t atomic_short;
+typedef atomic_generic_t atomic_ushort;
+//typedef atomic_generic_t atomic_int;
+typedef atomic_generic_t atomic_uint;
+//typedef atomic_generic_t atomic_long;
+typedef atomic_generic_t atomic_ulong;
+//typedef atomic_generic_t atomic_llong;
+//typedef atomic_generic_t atomic_ullong;
+//typedef atomic_generic_t atomic_char16_t;
+//typedef atomic_generic_t atomic_char32_t;
+//typedef atomic_generic_t atomic_wchar_t;
+//typedef atomic_generic_t atomic_int_least8_t;
+typedef atomic_generic_t atomic_uint_least8_t;
+//typedef atomic_generic_t atomic_int_least16_t;
+typedef atomic_generic_t atomic_uint_least16_t;
+//typedef atomic_generic_t atomic_int_least32_t;
+typedef atomic_generic_t atomic_uint_least32_t;
+//typedef atomic_generic_t atomic_int_least64_t;
+//typedef atomic_generic_t atomic_uint_least64_t;
+//typedef atomic_generic_t atomic_int_fast8_t;
+typedef atomic_generic_t atomic_uint_fast8_t;
+//typedef atomic_generic_t atomic_int_fast16_t;
+typedef atomic_generic_t atomic_uint_fast16_t;
+//typedef atomic_generic_t atomic_int_fast32_t;
+typedef atomic_generic_t atomic_uint_fast32_t;
+//typedef atomic_generic_t atomic_int_fast64_t
+//typedef atomic_generic_t atomic_uint_fast64_t;
+//typedef atomic_generic_t atomic_intptr_t;
+typedef atomic_generic_t atomic_uintptr_t;
+typedef atomic_generic_t atomic_size_t;
+//typedef atomic_generic_t atomic_ptrdiff_t;
+//typedef atomic_generic_t atomic_intmax_t;
+//typedef atomic_generic_t atomic_uintmax_t;
+
+#define atomic_store(object,desired) \
+    do { \
+        vlc_global_lock(VLC_ATOMIC_MUTEX); \
+        *(object) = (desired); \
+        vlc_global_unlock(VLC_ATOMIC_MUTEX); \
+    } while (0)
+
+#  define atomic_store_explicit(object,desired,order) \
+    atomic_store(object,desired)
+
+static inline uintptr_t atomic_load(atomic_generic_t *object)
+{
+    uintptr_t value;
+
+    vlc_global_lock(VLC_ATOMIC_MUTEX);
+    value = *object;
+    vlc_global_unlock(VLC_ATOMIC_MUTEX);
+    return value;
+}
+#  define atomic_load_explicit(object,order) \
+    atomic_load(object)
+
+static inline
+uintptr_t atomic_exchange(atomic_generic_t *object, uintptr_t desired)
+{
+    uintptr_t value;
+
+    vlc_global_lock(VLC_ATOMIC_MUTEX);
+    value = *object;
+    *object = desired;
+    vlc_global_unlock(VLC_ATOMIC_MUTEX);
+    return value;
+}
+#  define atomic_exchange_explicit(object,desired,order) \
+    atomic_exchange(object,desired)
+
+static inline
+bool vlc_atomic_compare_exchange(atomic_generic_t *object,
+                                 uintptr_t *expected, uintptr_t desired)
+{
+    bool ret;
+
+    vlc_global_lock(VLC_ATOMIC_MUTEX);
+    ret = *object == *expected;
+    if (ret)
+        *object = desired;
+    else
+        *expected = *object;
+    vlc_global_unlock(VLC_ATOMIC_MUTEX);
+    return ret;
+}
+#  define atomic_compare_exchange_strong(object,expected,desired) \
+    vlc_atomic_compare_exchange(object, expected, desired)
+#  define atomic_compare_exchange_strong_explicit(object,expected,desired,order) \
+    atomic_compare_exchange_strong(object, expected, desired)
+#  define atomic_compare_exchange_weak(object,expected,desired) \
+    vlc_atomic_compare_exchange(object, expected, desired)
+#  define atomic_compare_exchange_weak_explicit(object,expected,desired,order) \
+    atomic_compare_exchange_weak(object, expected, desired)
+
+static inline
+uintmax_t atomic_fetch_add(atomic_generic_t *object, uintptr_t operand)
+{
+    uintptr_t value;
+
+    vlc_global_lock(VLC_ATOMIC_MUTEX);
+    value = *object;
+    *object += operand;
+    vlc_global_unlock(VLC_ATOMIC_MUTEX);
+    return value;
+}
+#  define atomic_fetch_add_explicit(object,operand,order) \
+    atomic_fetch_add(object,operand)
+
+static inline
+uintptr_t atomic_fetch_sub(atomic_generic_t *object, uintptr_t operand)
+{
+    uintptr_t value;
+
+    vlc_global_lock(VLC_ATOMIC_MUTEX);
+    value = *object;
+    *object -= operand;
+    vlc_global_unlock(VLC_ATOMIC_MUTEX);
+    return value;
+}
+#  define atomic_fetch_sub_explicit(object,operand,order) \
+    atomic_fetch_sub(object,operand)
+
+static inline
+uintptr_t atomic_fetch_or(atomic_generic_t *object, uintptr_t operand)
+{
+    uintptr_t value;
+
+    vlc_global_lock(VLC_ATOMIC_MUTEX);
+    value = *object;
+    *object |= operand;
+    vlc_global_unlock(VLC_ATOMIC_MUTEX);
+    return value;
+}
+#  define atomic_fetch_or_explicit(object,operand,order) \
+    atomic_fetch_or(object,operand)
+
+static inline
+uintptr_t atomic_fetch_xor(atomic_generic_t *object, uintptr_t operand)
+{
+    uintptr_t value;
+
+    vlc_global_lock(VLC_ATOMIC_MUTEX);
+    value = *object;
+    *object ^= operand;
+    vlc_global_unlock(VLC_ATOMIC_MUTEX);
+    return value;
+}
+#  define atomic_fetch_xor_explicit(object,operand,order) \
+    atomic_fetch_sub(object,operand)
+
+static inline
+uintptr_t atomic_fetch_and(atomic_generic_t *object, uintptr_t operand)
+{
+    uintptr_t value;
+
+    vlc_global_lock(VLC_ATOMIC_MUTEX);
+    value = *object;
+    *object &= operand;
+    vlc_global_unlock(VLC_ATOMIC_MUTEX);
+    return value;
+}
+#  define atomic_fetch_and_explicit(object,operand,order) \
+    atomic_fetch_and(object,operand)
+
+#  define atomic_flag_test_and_set(object) \
+    atomic_exchange(object, true)
+
+#  define atomic_flag_test_and_set_explicit(object,order) \
+    atomic_flag_test_and_set(object)
+
+#  define atomic_flag_clear(object) \
+    atomic_store(object, false)
+
+#  define atomic_flag_clear_explicit(object,order) \
+    atomic_flag_clear(object)
+
 # endif
 
 /**

include/vlc_threads.h

@@ -563,6 +563,7 @@ enum {
    VLC_XLIB_MUTEX,
    VLC_MOSAIC_MUTEX,
    VLC_HIGHLIGHT_MUTEX,
+   VLC_ATOMIC_MUTEX,
    /* Insert new entry HERE */
    VLC_MAX_MUTEX
 };

src/misc/threads.c

@@ -42,6 +42,7 @@ void vlc_global_mutex (unsigned n, bool acquire)
         VLC_STATIC_MUTEX,
         VLC_STATIC_MUTEX,
         VLC_STATIC_MUTEX,
+        VLC_STATIC_MUTEX,
     };
     static_assert (VLC_MAX_MUTEX == (sizeof (locks) / sizeof (locks[0])),
                    "Wrong number of global mutexes");