lavc: Deprecate av_hwaccel_next() and av_register_hwaccel()

doc/APIchanges

@@ -15,6 +15,10 @@ libavutil:     2017-10-21
 
 API changes, most recent first:
 
+2017-11-xx - xxxxxxx - lavc 58.5.100 - avcodec.h
+  Deprecate user visibility of the AVHWAccel structure and the functions
+  av_register_hwaccel() and av_hwaccel_next().
+
 2017-11-xx - xxxxxxx - lavc 58.4.100 - avcodec.h
   Add AVCodecHWConfig and avcodec_get_hw_config().
 

libavcodec/avcodec.h

@@ -3489,6 +3489,10 @@ const AVCodecHWConfig *avcodec_get_hw_config(const AVCodec *codec, int index);
 
 /**
  * @defgroup lavc_hwaccel AVHWAccel
+ *
+ * @note  Nothing in this structure should be accessed by the user.  At some
+ *        point in future it will not be externally visible at all.
+ *
  * @{
  */
 typedef struct AVHWAccel {
@@ -3533,7 +3537,6 @@ typedef struct AVHWAccel {
      * New public fields should be added right above.
      *****************************************************************
      */
-    struct AVHWAccel *next;
 
     /**
      * Allocate a custom buffer
@@ -5874,17 +5877,26 @@ void av_fast_padded_mallocz(void *ptr, unsigned int *size, size_t min_size);
  */
 unsigned int av_xiphlacing(unsigned char *s, unsigned int v);
 
+#if FF_API_USER_VISIBLE_AVHWACCEL
 /**
  * Register the hardware accelerator hwaccel.
+ *
+ * @deprecated  This function doesn't do anything.
  */
+attribute_deprecated
 void av_register_hwaccel(AVHWAccel *hwaccel);
 
 /**
  * If hwaccel is NULL, returns the first registered hardware accelerator,
  * if hwaccel is non-NULL, returns the next registered hardware accelerator
  * after hwaccel, or NULL if hwaccel is the last one.
+ *
+ * @deprecated  AVHWaccel structures contain no user-serviceable parts, so
+ *              this function should not be used.
  */
+attribute_deprecated
 AVHWAccel *av_hwaccel_next(const AVHWAccel *hwaccel);
+#endif
 
 
 /**

libavcodec/utils.c

@@ -1898,22 +1898,16 @@ const AVCodecHWConfig *avcodec_get_hw_config(const AVCodec *codec, int index)
     return &codec->hw_configs[index]->public;
 }
 
-static AVHWAccel *first_hwaccel = NULL;
-static AVHWAccel **last_hwaccel = &first_hwaccel;
-
-void av_register_hwaccel(AVHWAccel *hwaccel)
+#if FF_API_USER_VISIBLE_AVHWACCEL
+AVHWAccel *av_hwaccel_next(const AVHWAccel *hwaccel)
 {
-    AVHWAccel **p = last_hwaccel;
-    hwaccel->next = NULL;
-    while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, hwaccel))
-        p = &(*p)->next;
-    last_hwaccel = &hwaccel->next;
+    return NULL;
 }
 
-AVHWAccel *av_hwaccel_next(const AVHWAccel *hwaccel)
+void av_register_hwaccel(AVHWAccel *hwaccel)
 {
-    return hwaccel ? hwaccel->next : first_hwaccel;
 }
+#endif
 
 int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op))
 {

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR  58
-#define LIBAVCODEC_VERSION_MINOR   4
+#define LIBAVCODEC_VERSION_MINOR   5
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
@@ -123,6 +123,9 @@
 #ifndef FF_API_CODEC_GET_SET
 #define FF_API_CODEC_GET_SET     (LIBAVCODEC_VERSION_MAJOR < 59)
 #endif
+#ifndef FF_API_USER_VISIBLE_AVHWACCEL
+#define FF_API_USER_VISIBLE_AVHWACCEL (LIBAVCODEC_VERSION_MAJOR < 59)
+#endif
 
 
 #endif /* AVCODEC_VERSION_H */