main: look for LOGO.BMP when idle

..and show that instead of the BornHack 2019 logo if found

main.c

@@ -28,6 +28,7 @@
 #include "power.h"
 #include "font.h"
 #include "display.h"
+#include "sdcard.h"
 #include "menu.h"
 
 #ifdef NDEBUG
@@ -51,14 +52,32 @@ static const struct button_config anypressed[BTN_MAX] = {
 
 extern const struct dp_cimage logo;
 
+static FRESULT show_logo(void)
+{
+ FATFS fs;
+ FRESULT res;
+
+ sd_init();
+
+ res = f_mount(&fs, "", 1);
+ if (res != FR_OK)
+ goto err;
+
+ res = dp_showbmp_at("LOGO.BMP", 0, 0);
+err:
+ sd_uninit();
+ return res;
+}
+
 static void
 idle(void)
 {
  struct ticker tick1s;
  unsigned int count = 0;
 
  dp_fill(0, 0, 240, 240, 0x000);
- dp_cimage(0, 10, &logo);
+ if (show_logo() != FR_OK)
+ dp_cimage(0, 10, &logo);
  buttons_config(anypressed);
 
  ticker_start(&tick1s, 1000, 2);