F.2 The Package Decimal

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Static Semantics​

1

The library package Decimal has the following declaration:

2/5
``````package Ada.Decimal
with  Pure is
3Max_Scale : constant := implementation-defined;
Min_Scale : constant := implementation-defined;
4Min_Delta : constant := 10.0**(-Max_Scale);
Max_Delta : constant := 10.0**(-Min_Scale);
5Max_Decimal_Digits : constant := implementation-defined;
6/3generic
type Dividend_Type  is delta <> digits <>;
type Divisor_Type   is delta <> digits <>;
type Quotient_Type  is delta <> digits <>;
type Remainder_Type is delta <> digits <>;
procedure Divide (Dividend  : in Dividend_Type;
Divisor   : in Divisor_Type;
Quotient  : out Quotient_Type;
Remainder : out Remainder_Type)
with Convention => Intrinsic;
``````
7.a
implementation defined
The values of named numbers in the package Decimal.
8

Max_Scale is the largest N such that 10.0**(–N) is allowed as a decimal type's delta. Its type is universal_integer.

9

Min_Scale is the smallest N such that 10.0**(–N) is allowed as a decimal type's delta. Its type is universal_integer.

10

Min_Delta is the smallest value allowed for delta in a `decimal_fixed_point_definition`. Its type is universal_real.

11

Max_Delta is the largest value allowed for delta in a `decimal_fixed_point_definition`. Its type is universal_real.

12

Max_Decimal_Digits is the largest value allowed for digits in a `decimal_fixed_point_definition`. Its type is universal_integer.

12.a
reason
The name is Max_Decimal_Digits versus Max_Digits, in order to avoid confusion with the named number System.Max_Digits relevant to floating point.

Static Semantics​

13

The effect of Divide is as follows. The value of Quotient is Quotient_Type(Dividend/Divisor). The value of Remainder is Remainder_Type(Intermediate), where Intermediate is the difference between Dividend and the product of Divisor and Quotient; this result is computed exactly.

Implementation Requirements​

14

Decimal.Max_Decimal_Digits shall be at least 18.

15

Decimal.Max_Scale shall be at least 18.

16

Decimal.Min_Scale shall be at most 0.

17
note
NOTE The effect of division yielding a quotient with control over rounding versus truncation is obtained by applying either the function attribute Quotient_Type'Round or the conversion Quotient_Type to the expression Dividend/Divisor.