drm-formats: add weston_drm_format_array_count_pairs()

It simply returns the number of format/modifier pairs in the array. This
will be useful for the next commits, in which we add support for dma-buf
feedback.

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>

libweston/drm-formats.c

@@ -184,6 +184,24 @@ weston_drm_format_array_find_format(const struct weston_drm_format_array *format
 	return NULL;
 }
 
+/**
+ * Counts the number of format/modifier pairs in a weston_drm_format_array
+ *
+ * @param formats The weston_drm_format_array
+ * @return The number of format/modifier pairs in the array
+ */
+WL_EXPORT unsigned int
+weston_drm_format_array_count_pairs(const struct weston_drm_format_array *formats)
+{
+	struct weston_drm_format *fmt;
+	unsigned int num_pairs = 0;
+
+	wl_array_for_each(fmt, &formats->arr)
+		num_pairs += fmt->modifiers.size / sizeof(uint64_t);
+
+	return num_pairs;
+}
+
 /**
  * Compare the content of two weston_drm_format_array
  *

libweston/libweston-internal.h

@@ -358,6 +358,9 @@ struct weston_drm_format *
 weston_drm_format_array_find_format(const struct weston_drm_format_array *formats,
 				    uint32_t format);
 
+unsigned int
+weston_drm_format_array_count_pairs(const struct weston_drm_format_array *formats);
+
 bool
 weston_drm_format_array_equal(const struct weston_drm_format_array *formats_A,
 			      const struct weston_drm_format_array *formats_B);

tests/drm-formats-test.c

@@ -81,6 +81,8 @@ TEST(basic_operations)
 
         weston_drm_format_array_init(&format_array);
 
+        assert(weston_drm_format_array_count_pairs(&format_array) == 0);
+
         ADD_FORMATS_AND_MODS(&format_array, formats, modifiers);
 
         for (i = 0; i < ARRAY_LENGTH(formats); i++) {
@@ -90,6 +92,9 @@ TEST(basic_operations)
                         assert(weston_drm_format_has_modifier(fmt, modifiers[j]));
         }
 
+        assert(weston_drm_format_array_count_pairs(&format_array) ==
+               ARRAY_LENGTH(formats) * ARRAY_LENGTH(modifiers));
+
         weston_drm_format_array_fini(&format_array);
 }