make inclusion of sources optional

include/config.h

 //#define DISABLE_CDC_DTR_CHECK
 #define DEBOUNCE_DELAY_MS 5
 
+#define DEBUG_DISK_WRITE_SOURCES
+
+#define DISK_BLOCK_SIZE 512
+
+#ifdef DEBUG_DISK_WRITE_SOURCES
+#define DISK_BLOCK_COUNT (256 + 128)
+#else // DEBUG_DISK_WRITE_SOURCES
+#define DISK_BLOCK_COUNT 128 // 128 is minimum size for fatfs lib
+#endif // DEBUG_DISK_WRITE_SOURCES
+
 #endif // __CONFIG_H__

include/fat_disk.h

  * See <http://www.gnu.org/licenses/>.
  */
 
-#define DISK_BLOCK_COUNT 300
-#define DISK_BLOCK_SIZE 512
-
 void fat_disk_init(void);
 
 uint8_t *fat_disk_get_sector(uint32_t sector);

src/debug_disk.c

 #include "log.h"
 #include "debug_disk.h"
 
+#ifdef DEBUG_DISK_WRITE_SOURCES
 #include "pack_data.h"
+#endif // DEBUG_DISK_WRITE_SOURCES
 
 static FATFS fs;
 static bool mounted = false;
 
-void debug_disk_init(void) {
-    if (debug_disk_mount() != 0) {
-        debug("error mounting disk");
-        return;
-    }
-
-    // maximum length: 11 bytes
-    f_setlabel("DEBUG DISK");
-
+static void write_readme(void) {
     FIL file;
     FRESULT res = f_open(&file, "README.md", FA_CREATE_ALWAYS | FA_WRITE);
     if (res != FR_OK) {
             debug("error: f_close returned %d", res);
         }
     }
+}
 
-    res = f_open(&file, "src.tar.xz", FA_CREATE_ALWAYS | FA_WRITE);
+#ifdef DEBUG_DISK_WRITE_SOURCES
+static void write_sources(void) {
+    FIL file;
+    FRESULT res = f_open(&file, "src.tar.xz", FA_CREATE_ALWAYS | FA_WRITE);
     if (res != FR_OK) {
         debug("error: f_open returned %d", res);
     } else {
             debug("error: f_close returned %d", res);
         }
     }
+}
+#endif // DEBUG_DISK_WRITE_SOURCES
+
+void debug_disk_init(void) {
+    if (debug_disk_mount() != 0) {
+        debug("error mounting disk");
+        return;
+    }
+
+    // maximum length: 11 bytes
+    f_setlabel("DEBUG DISK");
+
+    write_readme();
+
+#ifdef DEBUG_DISK_WRITE_SOURCES
+    write_sources();
+#endif // DEBUG_DISK_WRITE_SOURCES
 
     if (debug_disk_unmount() != 0) {
         debug("error unmounting disk");