Generated Initialization Functions

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As of ASN1C version 6.0, initialization functions are automatically generated (in previous versions, it was necessary to use the -genInit option to force this action). If for some reason, a user does want initialization functions to be generated, the -noInit switch can be used to turn initialization function generation off.

The use of initialization functions are optional - a variable can be initialized by simply setting its contents to zero (for example, by using the C run-time memset function). The advantage of initialization function is that they provide smarter initialization which can lead to improved application performance. For example, it is not necessary to set a large byte array to zero prior to its receiving a populated value. The use of memset in this situation can result in degraded performance.

Generated initialization functions are written to the main <module>.c file. This file contains common constants, global variables, and functions that are generic to all type of encode/decode functions. If the -cfile command-line option is used, the functions are written to the specified .c or .cpp file along with all other generated functions. If -maxcfiles is specified, each generated initialization function is written to a separate .c file.

The format of the name of each generated initialization function is as follows:

    asn1Init_[<prefix>]<prodName>		
 

where <prodName> is the name of the ASN.1 production for which the function is being generated and <prefix> is an optional prefix that can be set via a configuration file setting. The configuration setting used to set the prefix is the <typePrefix> element. This element specifies a prefix that will be applied to all generated typedef names and function names for the production.

The calling sequence for each generated initialization function is as follows:

    asn1Init_<name> (<name>* pvalue)
 

In this definition, <name> denotes the prefixed production name defined above.

The pvalue argument is used to pass a pointer to a variable of the item to be initialized.