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- (1)
- For each implementation there is a library package called System which includes the definitions of certain configuration-dependent characteristics.

- (2)
- The following language-defined library package exists:

(3) package System is pragma Preelaborate(System); (4) type Name is implementation-defined-enumeration-type; System_Name : constant Name := implementation-defined; (5)-- System-Dependent Named Numbers:(6) Min_Int : constant := root_integer'First; Max_Int : constant := root_integer'Last; (7) Max_Binary_Modulus : constant := implementation-defined; Max_Nonbinary_Modulus : constant := implementation-defined; (8) Max_Base_Digits : constant := root_real'Digits; Max_Digits : constant := implementation-defined; (9) Max_Mantissa : constant := implementation-defined; Fine_Delta : constant := implementation-defined; (10) Tick : constant := implementation-defined; (11)-- Storage-related Declarations:(12) type Address is implementation-defined; Null_Address : constant Address; (13) Storage_Unit : constant := implementation-defined; Word_Size : constant := implementation-defined * Storage_Unit; Memory_Size : constant := implementation-defined; (14)-- Address Comparison:function "<" (Left, Right : Address) return Boolean; function "<="(Left, Right : Address) return Boolean; function ">" (Left, Right : Address) return Boolean; function ">="(Left, Right : Address) return Boolean; function "=" (Left, Right : Address) return Boolean;-- function "/=" (Left, Right : Address) return Boolean;-- "/=" is implicitly definedpragma Convention(Intrinsic, "<"); ...-- and so on for all language-defined subprograms in this package(15)-- Other System-Dependent Declarations:type Bit_Order is (High_Order_First, Low_Order_First); Default_Bit_Order : constant Bit_Order; (16)-- Priority-related declarations (see D.1):subtype Any_Priority is Integer range implementation-defined; subtype Priority is Any_Priority range Any_Priority'First .. implementation-defined; subtype Interrupt_Priority is Any_Priority range Priority'Last+1 .. Any_Priority'Last; (17) Default_Priority : constant Priority := (Priority'First + Priority'Last)/2; (18) private ...-- not specified by the languageend System;

- (19)
- Name is an enumeration subtype. Values of type Name are the names of alternative machine configurations handled by the implementation. System_Name represents the current machine configuration.
- (20)
- The named numbers Fine_Delta and Tick are of the type universal_real; the others are of the type universal_integer.
- (21)
- The meanings of the named numbers are:
- (22)
- Min_Int
- The smallest (most negative) value allowed for the
expressions of a signed_integer_type_definition.

- (23)
- Max_Int
- The largest (most positive) value allowed for the expressions
of a signed_integer_type_definition.

- (24)
- Max_Binary_Modulus
- A power of two such that it, and all lesser positive powers
of two, are allowed as the modulus of a modular_type_definition.

- (25)
- Max_Nonbinary_Modulus
- A value such that it, and all lesser positive integers, are
allowed as the modulus of a modular_type_definition.

- (26)
- Max_Base_Digits
- The largest value allowed for the requested decimal precision
in a floating_point_definition.

- (27)
- Max_Digits
- The largest value allowed for the requested decimal precision
in a floating_point_definition that has no real_range_specification. Max_Digits is less than or equal to Max_Base_Digits.

- (28)
- Max_Mantissa
- The largest possible number of binary digits in the mantissa
of machine numbers of a user-defined ordinary fixed point
type. (The mantissa is defined in Annex G.)

- (29)
- Fine_Delta
- The smallest delta allowed in an ordinary_fixed_point_definition that has the real_range_specification range -1.0
.. 1.0.

- (30)
- Tick
- A period in seconds approximating the real time interval
during which the value of Calendar.Clock remains constant.

- (31)
- Storage_Unit
- The number of bits per storage element.

- (32)
- Word_Size
- The number of bits per word.

- (33)
- Memory_Size
- An implementation-defined value that is intended to reflect
the memory size of the configuration in storage elements.

- (34)
- Address is of a definite, nonlimited type. Address represents machine addresses capable of addressing individual storage elements. Null_Address is an address that is distinct from the address of any object or program unit.
- (35)
- See 13.5.3 for an explanation of Bit_Order and Default_Bit_Order.

- (36)
- An implementation may add additional implementation-defined declarations to package System and its children. However, it is usually better for the implementation to provide additional functionality via implementation-defined children of System. Package System may be declared pure.

- (37)
- Address should be of a private type.
- NOTES

- (38)
- (14) There are also some language-defined child packages of System
defined elsewhere.

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