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F.1 Machine_Radix Attribute Definition Clause

Static Semantics

   {specifiable (of Machine_Radix for decimal first subtypes) [partial]} {Machine_Radix clause} Machine_Radix may be specified for a decimal first subtype (see 3.5.9) via an attribute_definition_clause; the expression of such a clause shall be static, and its value shall be 2 or 10. A value of 2 implies a binary base range; a value of 10 implies a decimal base range.
Ramification: In the absence of a Machine_Radix clause, the choice of 2 versus 10 for S'Machine_Radix is not specified.

Implementation Advice

   Packed decimal should be used as the internal representation for objects of subtype S when S'Machine_Radix = 10.
Discussion: The intent of a decimal Machine_Radix attribute definition clause is to allow the programmer to declare an Ada decimal data object whose representation matches a particular COBOL implementation's representation of packed decimal items. The Ada object may then be passed to an interfaced COBOL program that takes a packed decimal data item as a parameter, assuming that convention COBOL has been specified for the Ada object's type in a pragma Convention.
Additionally, the Ada compiler may choose to generate arithmetic instructions that exploit the packed decimal representation.


   Example of Machine_Radix attribute definition clause:
type Money is delta 0.01 digits 15;
for Money'Machine_Radix use 10;

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