gcc/ada/s-arit64.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                      S Y S T E M . A R I T H _ 6 4                       --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2012, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This unit provides software routines for doing arithmetic on 64-bit
  33 --  signed integer values in cases where either overflow checking is
  34 --  required, or intermediate results are longer than 64 bits.
  35
  36 pragma Restrictions (No_Elaboration_Code);
  37 --  Allow direct call from gigi generated code
  38
  39 with Interfaces;
  40
  41 package System.Arith_64 is
  42    pragma Pure;
  43
  44    subtype Int64 is Interfaces.Integer_64;
  45
  46    function Add_With_Ovflo_Check (X, Y : Int64) return Int64;
  47    --  Raises Constraint_Error if sum of operands overflows 64 bits,
  48    --  otherwise returns the 64-bit signed integer sum.
  49
  50    function Subtract_With_Ovflo_Check (X, Y : Int64) return Int64;
  51    --  Raises Constraint_Error if difference of operands overflows 64
  52    --  bits, otherwise returns the 64-bit signed integer difference.
  53
  54    function Multiply_With_Ovflo_Check (X, Y : Int64) return Int64;
  55    pragma Export (C, Multiply_With_Ovflo_Check, "__gnat_mulv64");
  56    --  Raises Constraint_Error if product of operands overflows 64
  57    --  bits, otherwise returns the 64-bit signed integer product.
  58    --  GIGI may also call this routine directly.
  59
  60    procedure Scaled_Divide
  61      (X, Y, Z : Int64;
  62       Q, R    : out Int64;
  63       Round   : Boolean);
  64    --  Performs the division of (X * Y) / Z, storing the quotient in Q
  65    --  and the remainder in R. Constraint_Error is raised if Z is zero,
  66    --  or if the quotient does not fit in 64-bits. Round indicates if
  67    --  the result should be rounded. If Round is False, then Q, R are
  68    --  the normal quotient and remainder from a truncating division.
  69    --  If Round is True, then Q is the rounded quotient. The remainder
  70    --  R is not affected by the setting of the Round flag.
  71
  72    procedure Double_Divide
  73      (X, Y, Z : Int64;
  74       Q, R    : out Int64;
  75       Round   : Boolean);
  76    --  Performs the division X / (Y * Z), storing the quotient in Q and
  77    --  the remainder in R. Constraint_Error is raised if Y or Z is zero,
  78    --  or if the quotient does not fit in 64-bits. Round indicates if the
  79    --  result should be rounded. If Round is False, then Q, R are the normal
  80    --  quotient and remainder from a truncating division. If Round is True,
  81    --  then Q is the rounded quotient. The remainder R is not affected by the
  82    --  setting of the Round flag.
  83
  84 end System.Arith_64;