lavu: add helper functions for integer lists.

Add av_int_list_length() to compute a list length.
Add av_opt_set_int_list() to set a binary option.
Signed-off-by: Nicolas George <nicolas.george@normalesup.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/APIchanges

@@ -15,6 +15,10 @@ libavutil:     2012-10-22
 
 API changes, most recent first:
 
+2013-04-10 - xxxxxxx - lavu 25.26.100 - avutil.h,opt.h
+  Add av_int_list_length()
+  and av_opt_set_int_list().
+
 2013-03-30 - xxxxxxx - lavu 52.24.100 - samplefmt.h
   Add av_samples_alloc_array_and_samples().
 

libavutil/avutil.h

@@ -252,6 +252,27 @@ static inline void *av_x_if_null(const void *p, const void *x)
     return (void *)(intptr_t)(p ? p : x);
 }
 
+/**
+ * Compute the length of an integer list.
+ *
+ * @param elsize  size in bytes of each list element (only 1, 2, 4 or 8)
+ * @param term    list terminator (usually 0 or -1)
+ * @param list    pointer to the list
+ * @return  length of the list, in elements, not counting the terminator
+ */
+unsigned av_int_list_length_for_size(unsigned elsize,
+                                     const void *list, uint64_t term);
+
+/**
+ * Compute the length of an integer list.
+ *
+ * @param term  list terminator (usually 0 or -1)
+ * @param list  pointer to the list
+ * @return  length of the list, in elements, not counting the terminator
+ */
+#define av_int_list_length(list, term) \
+    av_int_list_length_for_size(sizeof(*list), list, term)
+
 /**
  * @}
  * @}

libavutil/opt.h

@@ -656,6 +656,20 @@ int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_
 int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags);
 int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags);
 int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags);
+
+/**
+ * Set a binary option to an integer list.
+ *
+ * @param obj    AVClass object to set options on
+ * @param name   name of the binary option
+ * @param val    pointer to an integer list (must have the correct type with
+ *               regard to the contents of the list)
+ * @param term   list terminator (usually 0 or -1)
+ * @param flags  search flags
+ */
+#define av_opt_set_int_list(obj, name, val, term, flags) \
+    av_opt_set_bin(obj, name, (const uint8_t *)val, \
+                   av_int_list_length(val, term) * sizeof(*val), flags)
 /**
  * @}
  */

libavutil/utils.c

@@ -79,3 +79,22 @@ char av_get_picture_type_char(enum AVPictureType pict_type)
     default:                 return '?';
     }
 }
+
+unsigned av_int_list_length_for_size(unsigned elsize,
+                                     const void *list, uint64_t term)
+{
+    unsigned i;
+
+    if (!list)
+        return 0;
+#define LIST_LENGTH(type) \
+    { type t = term, *l = list; for (i = 0; l[i] != t; i++); }
+    switch (elsize) {
+    case 1: LIST_LENGTH(uint8_t);  break;
+    case 2: LIST_LENGTH(uint16_t); break;
+    case 4: LIST_LENGTH(uint32_t); break;
+    case 8: LIST_LENGTH(uint64_t); break;
+    default: av_assert0(!"valid element size");
+    }
+    return i;
+}