Vim Script Intel HEX Checksum

ihex.vim

function IHexChecksum()
  let l:data = getline(".")
  let l:dlen = strlen(data)

  if (empty(matchstr(l:data, "^:\\(\\x\\x\\)\\{5,}$")))
    echoerr("Input is not a valid Intel HEX line!")
    return
  endif

  let l:byte = 0
  for l:bytepos in range(1, l:dlen-4, 2)
    let l:byte += str2nr(strpart(l:data, l:bytepos, 2), 16)
  endfor

  let l:byte = (256-(l:byte%256))%256
  call setline(".", strpart(l:data, 0, l:dlen-2).printf("%02x", l:byte))
endfunction