--- /dev/null
+# About
+
+ASN.1 to C compiler takes the ASN.1 module files (example) and generates
+the C++ compatible C source code. That code can be used to serialize
+the native C structures into compact and unambiguous BER/OER/PER/XER-based
+data files, and deserialize the files back.
+
+Various ASN.1 based formats are widely used in the industry,
+such as to encode the X.509 certificates employed in the HTTPS handshake,
+to exchange control data between mobile phones and cellular networks,
+to perform car-to-car communication in intelligent transportation networks.
+
+The ASN.1 family of standards is large and complex, and no open source
+compiler supports it in its entirety.
+The asn1c is arguably the most evolved open source ASN.1 compiler.
+
+# ASN.1 Transfer Syntaxes
+<details>
+<summary>ASN.1 encodings interoperability table</summary>
+
+The ASN.1 family of standards define a number of ways to encode data,
+including byte-oriented (e.g., BER), bit-oriented (e.g., PER),
+and textual (e.g., XER). Some encoding variants (e.g., DER) are just stricter
+variants of the more general encodings (e.g., BER).
+
+The interoperability table below specifies which API functions can be used
+to exchange data in a compatible manner. If you need to _produce_ data
+conforming to the standard specified in the column 1,
+use the API function in the column 2.
+If you need to _process_ data conforming to the standard(s) specified in the
+column 3, use the API function specified in column 4.
+See the [doc/asn1c-usage.pdf](doc/asn1c-usage.pdf) for details.
+
+Encoding | API function | Understood by | API function
+-------------- | ------------------ | ------------- | -------------
+BER | der_encode() | BER | ber_decode()
+DER | der_encode() | DER, BER | ber_decode()
+CER | _not supported_ | CER, BER | ber_decode()
+BASIC-OER | oer_encode() | *-OER | oer_decode()
+CANONICAL-OER | oer_encode() | *-OER | oer_decode()
+BASIC-UPER | uper_encode() | *-UPER | uper_decode()
+CANONICAL-UPER | uper_encode() | *-UPER | uper_decode()
+*-APER | _not supported_ | *-APER | _not supported_
+BASIC-XER | xer_encode(XER_F_BASIC) | *-XER | xer_decode()
+CANONICAL-XER | xer_encode(XER_F_CANONICAL)| *-XER | xer_decode()
+
+*) Asterisk means both BASIC and CANONICAL variants.
+</details>
+
+# Build and Install
+
+If you haven't installed the asn1c yet, read the [INSTALL.md](INSTALL.md) file
+for a short installation guide.
+
+[](https://travis-ci.org/vlm/asn1c)
+
+# Documentation
+
+For the list of asn1c command line options, see `asn1c -h` or `man asn1c`.
+
+The comprehensive documentation on this compiler is in [doc/asn1c-usage.pdf](doc/asn1c-usage.pdf).
+
+Please also read the [FAQ](FAQ) file.
+
+An excellent book on ASN.1 is written by Olivier Dubuisson:
+"ASN.1 Communication between heterogeneous systems", ISBN:0-12-6333361-0.
+
+# Quick start
+
+(also check out [doc/asn1c-quick.pdf](doc/asn1c-quick.pdf))
+
+After installing the compiler (see [INSTALL.md](INSTALL.md)), you may use
+the asn1c command to compile the ASN.1 specification:
+
+ asn1c <module.asn1> # Compile module
+
+If several specifications contain interdependencies, all of them must be
+specified at the same time:
+
+ asn1c <module1.asn1> <module2.asn1> ... # Compile interdependent modules
+
+The asn1c source tarball contains the [examples/](examples/) directory
+with several ASN.1 modules and a [script](examples/crfc2asn1.pl)
+to extract the ASN.1 modules from RFC documents.
+Refer to the [examples/README](examples/README) file in that directory.
+
+To compile the X.509 PKI module:
+
+ ./asn1c/asn1c -P ./examples/rfc3280-*.asn1 # Compile-n-print
+
+In this example, the **-P** option is to print the compiled text on the
+standard output. The default behavior is that asn1c compiler creates
+multiple .c and .h files for every ASN.1 type found inside the specified
+ASN.1 modules.
+
+The compiler's **-E** and **-EF** options are used for testing the parser and
+the semantic fixer, respectively. These options will instruct the compiler
+to dump out the parsed (and fixed) ASN.1 specification as it was
+"understood" by the compiler. It might be useful for checking
+whether a particular syntactic construction is properly supported
+by the compiler.
+
+ asn1c -EF <module-to-test.asn1> # Check semantic validity
+
+# Model of operation
+
+The asn1c compiler works by processing the ASN.1 module specifications
+in several stages:
+
+1. During the first stage, the ASN.1 file is parsed.
+ (Parsing produces an ASN.1 syntax tree for the subsequent levels)
+2. During the second stage, the syntax tree is "fixed".
+ (Fixing is a process of checking the tree for semantic errors,
+ accompanied by the tree transformation into the canonical form)
+3. During the third stage, the syntax tree is compiled into the target language.
+
+There are several command-line options reserved for printing the results
+after each stage of operation:
+
+ <parser> => print (-E)
+ <parser> => <fixer> => print (-E -F)
+ <parser> => <fixer> => <compiler> => print (-P)
+ <parser> => <fixer> => <compiler> => save-compiled [default]
+
+
+--
+Lev Walkin
+vlm@lionet.info
Code Review / com / asn1c.git / blobdiff