Chapter 3 Ada Language Reference© National Instruments Corporation 3-17 AutoCode ReferenceFixed-Point Data TypesFixed-point type declarations exist in the file named: sa_fxptypes_.aand is provided in the System-Specific Files src (source) directory. 1This file contains the specification of the SA_FIXED package. The packagespecification contains all of the type declarations with the appropriatedelta and range for each type. Refer to the AutoCode Reference for moreinformation about the fixed-point type sizes, radix ranges and namingconventions.Note Ada uses the term delta to describe the accuracy of a fixed-point type.AutoCode/Ada uses the term radix to denote a type’s accuracy. The relationship betweenthe two is: delta = 2 –radix. Thus, a fixed-point type with a delta of 0.125 is a fixed-point typewith radix 3.Generic FunctionsGeneric functions that implement functionality of standard operationsare found in the two files named: sa_fxpgenerics_.a andsa_fxpgenerics.a. These files provide the specification and body forthe SA_FIXED_GENERICS package. These files are also provided in theSystem-Specific Files src directory. These generic functions are the basisfor the creation of the overloaded operators to perform the appropriatearithmetic operation.Instantiated FunctionsDue to the large number of combinations of operations and fixed-pointtypes, only those operations that are used in the model areinstantiated—that is, only the instances of the functions that are required bya model are actually created. Thus, an additional file is created by the codegenerator when generating code for a model that uses fixed-point types.This file is generated from the template. The default template generates oneadditional file that contains a package specification containing all of theinstantiated functions for the model. The package name isRT_FIXED_OPERATORS and the file is named fxp_outputfile_.a,whereoutputfile is the name of the model or other name as specified ina command option to AutoCode.1 The file name convention uses an underscore before the extension to denote a file containing a package specification.The .a extension is arbitrary as different platforms use different extensions, like .ada.
