public static ulong GetDecompressedSize(ReadOnlySpan <byte> src) { var size = ExternMethods.ZSTD_getFrameContentSize(src, (size_t)src.Length); if (size == ExternMethods.ZSTD_CONTENTSIZE_UNKNOWN) { throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_GENERIC, "Decompressed content size is not specified"); } if (size == ExternMethods.ZSTD_CONTENTSIZE_ERROR) { throw new ZstdException(ZSTD_ErrorCode.ZSTD_error_GENERIC, "Decompressed content size cannot be determined (e.g. invalid magic number, srcSize too small)"); } return(size); }