trezor-firmware/bootloader/firmware_align.py

#!/usr/bin/env python3
import sys
import os

TOTALSIZE = 32768
MAXSIZE = TOTALSIZE - 32

fn = sys.argv[1]
fs = os.stat(fn).st_size
if fs > MAXSIZE:
	raise Exception('bootloader has to be smaller than %d bytes (current size is %d)' % (MAXSIZE, fs))
with open(fn, 'ab') as f:
	f.write(b'\x00' * (TOTALSIZE - fs))
	f.close()