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-------------------------------------------------------------------------------
--- --
--- GNAT COMPILER COMPONENTS --
--- --
--- I N T E R F A C E S . P A C K E D _ D E C I M A L --
--- --
--- S p e c --
--- (Version for IBM Mainframe Packed Decimal Format) --
--- --
--- $Revision: 1.1.16.2 $
--- --
--- Copyright (C) 1992,1993,1994,1995 Free Software Foundation, Inc. --
--- --
--- GNAT is free software; you can redistribute it and/or modify it under --
--- terms of the GNU General Public License as published by the Free Soft- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
--- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
--- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
--- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
--- --
--- As a special exception, if other files instantiate generics from this --
--- unit, or you link this unit with other files to produce an executable, --
--- this unit does not by itself cause the resulting executable to be --
--- covered by the GNU General Public License. This exception does not --
--- however invalidate any other reasons why the executable file might be --
--- covered by the GNU Public License. --
--- --
--- GNAT was originally developed by the GNAT team at New York University. --
--- Extensive contributions were provided by Ada Core Technologies Inc. --
--- --
-
--- This unit defines the packed decimal format used by GNAT in response to
--- a specication of Machine_Radix 10 for a decimal fixed-point type. The
--- format and operations are completely encapsulated in this unit, so all
--- that is necessary to compile using different packed decimal formats is
--- to replace this single unit.
-
--- Note that the compiler access the spec of this unit during compilation
--- to obtain the data length that needs allocating, so the correct version
--- of the spec must be available to the compiler, and must correspond to
--- the spec and body made available to the linker, and all units of a given
--- program must be compiled with the same version of the spec and body.
--- This consistency will be enforced automatically using the normal binder
--- consistency checking, since any unit declaring Machine_Radix 10 types or
--- containing operations on such data will implicitly with Packed_Decimal.
-
-with System;
-
-package Interfaces.Packed_Decimal is
-
- ------------------------
- -- Format Description --
- ------------------------
-
- -- IBM Mainframe packed decimal format uses a byte string of length one
- -- to 10 bytes, with the most significant byte first. Each byte contains
- -- two decimal digits (with the high order digit in the left nibble, and
- -- the low order four bits contain the sign, using the following code:
-
- -- 16#A# 2#1010# positive
- -- 16#B# 2#1011# negative
- -- 16#C# 2#1100# positive (preferred representation)
- -- 16#D# 2#1101# negative (preferred representation)
- -- 16#E# 2#1110# positive
- -- 16#F# 2#1011# positive
-
- -- In this package, all six sign representations are interpreted as
- -- shown above when an operand is read, when an operand is written,
- -- the preferred representations are always used. Constraint_Error
- -- is raised if any other bit pattern is found in the sign nibble,
- -- or if a digit nibble contains an invalid digit code.
-
- -- Some examples follow:
-
- -- 05 76 3C +5763
- -- 00 01 1D -11
- -- 00 04 4E +44 (non-standard sign)
- -- 00 00 00 invalid (incorrect sign nibble)
- -- 0A 01 1C invalid (bad digit)
-
- ------------------
- -- Length Array --
- ------------------
-
- -- The following array must be declared in exactly the form shown, since
- -- the compiler accesses the associated tree to determine the size to be
- -- allocated to a machine radix 10 type, depending on the number of digits.
-
- subtype Byte_Length is Positive range 1 .. 10;
- -- Range of possible byte lengths
-
- Packed_Size : constant array (1 .. 18) of Byte_Length :=
- (01 => 01, -- Length in bytes for digits 1
- 02 => 02, -- Length in bytes for digits 2
- 03 => 02, -- Length in bytes for digits 2
- 04 => 03, -- Length in bytes for digits 2
- 05 => 03, -- Length in bytes for digits 2
- 06 => 04, -- Length in bytes for digits 2
- 07 => 04, -- Length in bytes for digits 2
- 08 => 05, -- Length in bytes for digits 2
- 09 => 05, -- Length in bytes for digits 2
- 10 => 06, -- Length in bytes for digits 2
- 11 => 06, -- Length in bytes for digits 2
- 12 => 07, -- Length in bytes for digits 2
- 13 => 07, -- Length in bytes for digits 2
- 14 => 08, -- Length in bytes for digits 2
- 15 => 08, -- Length in bytes for digits 2
- 16 => 09, -- Length in bytes for digits 2
- 17 => 09, -- Length in bytes for digits 2
- 18 => 10); -- Length in bytes for digits 2
-
- -------------------------
- -- Conversion Routines --
- -------------------------
-
- subtype D32 is Positive range 1 .. 9;
- -- Used to represent number of digits in a packed decimal value that
- -- can be represented in a 32-bit binary signed integer form.
-
- subtype D64 is Positive range 10 .. 18;
- -- Used to represent number of digits in a packed decimal value that
- -- requires a 64-bit signed binary integer for representing all values.
-
- function Packed_To_Int32 (P : System.Address; D : D32) return Integer_32;
- -- The argument P is the address of a packed decimal value and D is the
- -- number of digits (in the range 1 .. 9, as implied by the subtype).
- -- The returned result is the corresponding signed binary value. The
- -- exception Constraint_Error is raised if the input is invalid.
-
- function Packed_To_Int64 (P : System.Address; D : D64) return Integer_64;
- -- The argument P is the address of a packed decimal value and D is the
- -- number of digits (in the range 10 .. 18, as implied by the subtype).
- -- The returned result is the corresponding signed binary value. The
- -- exception Constraint_Error is raised if the input is invalid.
-
- procedure Int32_To_Packed (V : Integer_32; P : System.Address; D : D32);
- -- The argument V is a signed binary integer, which is converted to
- -- packed decimal format and stored using P, the address of a packed
- -- decimal item of D digits (D is in the range 1-9). Constraint_Error
- -- is raised if V is out of range of this number of digits.
-
- procedure Int64_To_Packed (V : Integer_64; P : System.Address; D : D64);
- -- The argument V is a signed binary integer, which is converted to
- -- packed decimal format and stored using P, the address of a packed
- -- decimal item of D digits (D is in the range 10-18). Constraint_Error
- -- is raised if V is out of range of this number of digits.
-
-end Interfaces.Packed_Decimal;
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