Avoid division by spec->blocksize in cipher mode handlers
* cipher/cipher-internal.h (_gcry_blocksize_shift): New. * cipher/cipher-cbc.c (_gcry_cipher_cbc_encrypt) (_gcry_cipherp_cbc_decrypt): Use bit-level operations instead of division to get number of blocks and check input length against blocksize. * cipher/cipher-cfb.c (_gcry_cipher_cfb_encrypt) (_gcry_cipher_cfb_decrypt): Ditto. * cipher/cipher-cmac.c (_gcry_cmac_write): Ditto. * cipher/cipher-ctr.c (_gcry_cipher_ctr_crypt): Ditto. * cipher/cipher-ofb.c (_gcry_cipher_ofb_encrypt) (_gcry_cipher_ofb_decrypt): Ditto.
Integer division was causing 10 to 20 cycles per call overhead
for cipher modes on x86-64.
- Signed-off-by: Jussi Kivilinna <firstname.lastname@example.org>