g10/decrypt-data: use iobuf_read for higher performance

* g10/decrypt-data.c (fill_buffer): Use iobuf_read instead of iobuf_get
for reading data.
--

This patch reduces iobuf_read per byte processing overhead and speeds
up decryption.

Benchmark results below, tested on Intel Core i7-4790K (turbo off).
Encrypted 2 GiB through pipe to ramfs file using AES128. Decrypt
ramfs file out through pipe to /dev/null.

before patch-set
----------------
	       gpg process
no-armor:      user time    pipe transfer rate
 encrypt-aead:  1.02         1.0 GB/s
 decrypt-aead:  10.8         185 MB/s
 encrypt-cfb:   4.8          342 MB/s
 decrypt-cfb:   12.7         157 MB/s

               gpg process
armor:         user time    pipe transfer rate
 encrypt-aead:  13.8         140 MB/s
 decrypt-aead:  30.6         68 MB/s
 encrypt-cfb:   17.4         114 MB/s
 decrypt-cfb:   32.6         64 MB/s

after (decrypt opt)
-------------------
               gpg process
no-armor:      user time    pipe transfer rate
 decrypt-aead:  7.3          263 MB/s
 decrypt-cfb:   9.3          211 MB/s

               gpg process
armor:         user time    pipe transfer rate
 decrypt-aead:  27.0         77 MB/s
 decrypt-cfb:   29.0         72 MB/s

Note: decryption results are much slower than encryption because of
extra SHA1 & RIPEMD160 hashing.

GnuPG-bug-id: 3786
Signed-off-by: Jussi Kivilinna <[email protected]>

0 files changed, 0 insertions, 0 deletions