------------------------------------------------------------------------------ -- -- -- 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) -- -- -- -- Copyright (C) 1992-2024, 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 3, 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. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- . -- -- -- -- 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 specification 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;