* Example usage:
* \code
* Flash fls;
-* flash_init(&fls.blk, 0);
+* flash_init(&fls, 0);
* // enable access only on desired blocks
* // start block = 50, num blocks = 20
-* kblock_trim(&fls, 50, 20);
+* kblock_trim(&fls.blk, 50, 20);
* // ...
* // now write to the flash
* // block number is automatically converted