函数 av_ripemd_init 

pub unsafe extern "C" fn av_ripemd_init(
    context: *mut AVRIPEMD,
    bits: c_int,
) -> c_int

Initialize RIPEMD hashing.

@param context pointer to the function context (of size av_ripemd_size) @param bits number of bits in digest (128, 160, 256 or 320 bits) @return zero if initialization succeeded, -1 otherwise