NOTE: This section assumes standard memory-buffer based decoding is to be done. If stream-based decoding is to be done (specified by adding -stream to the ASN1C command-line), see the Generated BER Streaming Decode Functions section for correct procedures on using the stream-based functions.

For each ASN.1 production defined in an ASN.1 source file, a C decode function is generated. This function will decode an ASN.1 message into a C variable of the given type.

If C++ code generation is specified, a control class is generated that contains a Decode method that wraps this function. This function is invoked through the class interface to decode an ASN.1 message into the variable referenced in the msgData component of the class.