On 11.07.2017 12:30, Gilad Ben-Yossef wrote: > On Tue, Jul 11, 2017 at 10:52 AM, Kamil Konieczny > <k.konieczny@xxxxxxxxxxxxxxxxxxx> wrote: >> >> >> I am writing crypto driver for hash MD5/SHA1/SHA256 on Exynos 4412, >> and I am facing some (minor?) difficulties. [...] >> So there is no [...] final method. >> >> It must be feeded with at least one message byte to produce hash. >> >> One more constrain is to process data in constant-sized chunks, >> here it is 64 bytes, the same as for AES block, >> i.e. it cannot stop and export state while in middle of block, >> example - if we feed 16 bytes, we must then feed 48 bytes >> to stop, but ideally we should feed it always 64 bytes. [...] >> >> Any suggestions ? >> >> Can i keep some bytes unfeeded from ahash_request >> and return -EINPROGRESS ? >> Should i set timer and copy rest bytes after some timeout, >> where no more requests are incoming ? Or not ? cause it is >> async mode ? >> can i wait for more requests for processing waiting one ? > Your two constraints are actually inter-related - > > If you can only feed the HW a constant size chunk, than indeed need to > keey bytes fed > to the driver the are below the chunk size in a software buffer, but > than you need the final() > method to feed these bytes (padded as needed) to the HW if they are > the last bytes > > Gilad HW will done padding I want to avoid memcpy iff possible for async hash -- Best regards, Kamil Konieczny Samsung R&D Institute Poland
