The block header size is 80 Byte (640 bits) so we must pad it to a multiple of 512 (In our case to 1024) like this:
(blockheader in binary)+1+00000.....000+1010000000
where "1010000000" is the size of blockheader in binary representation
Is this correct?
I am confused because in this link https://security.stackexchange.com/questions/179282/how-is-the-bitcoin-block-header-data-padded-for-sha256-hashin
it pad like this
blockheader+1+ 00...000+110 0100 0000