Function zstd_sys::ZSTD_estimateCDictSize

pub unsafe extern "C" fn ZSTD_estimateCDictSize(
    dictSize: usize, 
    compressionLevel: c_int
) -> usize

ZSTD_estimate?DictSize() : ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict(). ZSTD_estimateCStreamSize_advanced_usingCParams() makes it possible to control precisely compression parameters, like ZSTD_createCDict_advanced(). Note : dictionary created by reference using ZSTD_dlm_byRef are smaller