proc av_sha512_alloc(): ptr AVSHA512 {.importc, cdecl, ...raises: [], tags: [],
                                       forbids: [].}

proc av_sha512_final(context: ptr AVSHA512; digest: ptr uint8) {.importc, cdecl,
    ...raises: [], tags: [], forbids: [].}

proc av_sha512_init(context: ptr AVSHA512; bits: cint): cint {.importc, cdecl,
    ...raises: [], tags: [], forbids: [].}

proc av_sha512_update(context: ptr AVSHA512; data: ptr uint8; len: csize_t) {.
    importc, cdecl, ...raises: [], tags: [], forbids: [].}