The ASN.1 compiler for C is a standalone program that takes one or more input files, where each input file contains one or more ASN.1 modules, and generates C source code for encoding and decoding ASN.1 messages. The compiler verifies that the ASN.1 schema is valid, and generates the following:
The ASN.1 Tools for C also supports cross compiling. Cross compiling enables developers to produce files that can be used on a different operating system than the one the compiler runs on. Maximize your investment with the ability to cross-compile. Learn more about cross-compilation.
For a complete list of features, see Features shared across all OSS ASN.1 Tools.
The OSS encoders/decoders provide, among many other features, the ossEncode() and ossDecode() functions. The ossEncode() function takes data placed by your application program in the compiler-generated C data structures and converts it to a string of bytes encoded according to BER, DER, CER, PER, UPER, CPER, CUPER, OER, COER, XER, CXER, E-XER, JSON, or AVN.
This utility, included with the ASN.1 Tools for C, takes a BER or DER encoding in ASCII or binary format from an input file and writes it to an output file in one of three different type-length-value (TLV) formats.
The ossDecode() function takes a string of bytes that have been encoded according to BER, DER, CER, PER, UPER, CPER, CUPER, OER, COER, XER, CXER, E-XER, JSON, or AVN and performs the inverse operation of the encoder, resulting in a C data structure that you can easily manipulate.
The space-optimized encoder/decoder (SOED) is so named because its emphasis is on minimizing use of memory, especially when the abstract syntax is large or complex. Both the encoder and decoder possess a simple yet flexible memory management interface as well as a wealth of tracing, error trapping, diagnostic and recovery capabilities.
The time-optimized encoder/decoder (TOED) has a program call interface identical to the space-optimized encoder/decoder's and performs the same function (except that it does not possess any tracing capability), but its emphasis is on minimizing CPU utilization.
The OSS runtime libraries have been ported to 500+ platforms, including many embedded platforms.
See Runtime Choices to find the right encoder/decoder that suits your specific needs.
The Interpretive ASN.1 API (IAAPI), included at no extra cost in the ASN.1 Tools for C, can be used in conjunction with the regular ASN.1 compiler for C (when the ASN.1 schema is compiled at the time when the application is developed), or with OSS' Compile-And-Go Library (CAGL) (when the schema is compiled dynamically at runtime).
IAAPI provides means to get information about the details of a compiled ASN.1 schema, including the types it defines (say, a record with multiple components), the fields of a type (say, an integer and a string) and the constraints associated with them (say, a smaller-than-10 integer). This information allows developers to write code that parses the content of a message, which is particularly useful when its structure is unknown at application development time. Similarly, developers can write code to create, field by field, a new message, so long as its format obeys the schema compiled.
IAAPI supports ASN.1 BER, DER, CER, PER, UPER, CPER, CUPER, OER, COER, XER, CXER, E-XER, CSV, JSON, and AVN.
Our ASN.1 compiler for C and ASN.1 encoders/decoders are fully compliant with all ASN.1 standards. We support: 2021, 2015, 2008, 2002, 1997, 1994, and 1990. For a complete list, see the Standards Conformance page.
More information about how to create, compile and link your ASN.1 application using the ASN.1/C Tools.
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