get_splashscreeen: add assertions

Author: MartinPulec

src/video_display.c

@@ -630,9 +630,14 @@ struct video_frame *get_splashscreen()
 {
         struct video_desc desc;
 
-        desc.width = 512;
-        desc.height = 512;
-        desc.color_spec = RGBA;
+        enum {
+                FBUF_W  = 512,
+                FBUF_H  = 512,
+                FBUF_CS = RGBA,
+        };
+        desc.width       = FBUF_W;
+        desc.height      = FBUF_H;
+        desc.color_spec  = (codec_t) FBUF_CS;
         desc.interlacing = PROGRESSIVE;
         desc.fps = 1;
         desc.tile_count = 1;
@@ -641,6 +646,10 @@ struct video_frame *get_splashscreen()
 
         const char *data = splash_data;
         memset(frame->tiles[0].data, 0, frame->tiles[0].data_len);
+        // center the pixture; framebuffer size must be greater or equal
+        // the splash size
+        _Static_assert(splash_width >= FBUF_W && splash_height >= FBUF_H,
+                       "framebuffer smaller than splash size");
         for (unsigned int y = 0; y < splash_height; ++y) {
                 char *line = frame->tiles[0].data;
                 line += vc_get_linesize(frame->tiles[0].width,
@@ -649,6 +658,7 @@ struct video_frame *get_splashscreen()
                 line += vc_get_linesize(
                                 (frame->tiles[0].width - splash_width)/2,
                                 frame->color_spec);
+                _Static_assert((codec_t) FBUF_CS == RGBA, "RGBA is expected");
                 for (unsigned int x = 0; x < splash_width; ++x) {
                         HEADER_PIXEL(data,line);
                         line += 4;