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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT COMPILER COMPONENTS --
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4 -- --
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5 -- S Y S T E M . A R I T H _ 6 4 --
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6 -- --
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7 -- S p e c --
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8 -- --
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9 -- Copyright (C) 1992-2019, Free Software Foundation, Inc. --
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 -- This unit provides software routines for doing arithmetic on 64-bit
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33 -- signed integer values in cases where either overflow checking is
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34 -- required, or intermediate results are longer than 64 bits.
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35
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36 pragma Restrictions (No_Elaboration_Code);
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37 -- Allow direct call from gigi generated code
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38
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39 with Interfaces;
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40
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41 package System.Arith_64 is
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42 pragma Pure;
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43
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44 subtype Int64 is Interfaces.Integer_64;
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45
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46 function Add_With_Ovflo_Check (X, Y : Int64) return Int64;
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47 -- Raises Constraint_Error if sum of operands overflows 64 bits,
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48 -- otherwise returns the 64-bit signed integer sum.
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49
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50 function Subtract_With_Ovflo_Check (X, Y : Int64) return Int64;
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51 -- Raises Constraint_Error if difference of operands overflows 64
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52 -- bits, otherwise returns the 64-bit signed integer difference.
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53
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54 function Multiply_With_Ovflo_Check (X, Y : Int64) return Int64;
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55 pragma Export (C, Multiply_With_Ovflo_Check, "__gnat_mulv64");
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56 -- Raises Constraint_Error if product of operands overflows 64
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57 -- bits, otherwise returns the 64-bit signed integer product.
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58 -- GIGI may also call this routine directly.
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59
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60 procedure Scaled_Divide
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61 (X, Y, Z : Int64;
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62 Q, R : out Int64;
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63 Round : Boolean);
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64 -- Performs the division of (X * Y) / Z, storing the quotient in Q
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65 -- and the remainder in R. Constraint_Error is raised if Z is zero,
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66 -- or if the quotient does not fit in 64-bits. Round indicates if
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67 -- the result should be rounded. If Round is False, then Q, R are
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68 -- the normal quotient and remainder from a truncating division.
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69 -- If Round is True, then Q is the rounded quotient. The remainder
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70 -- R is not affected by the setting of the Round flag.
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71
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72 procedure Double_Divide
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73 (X, Y, Z : Int64;
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74 Q, R : out Int64;
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75 Round : Boolean);
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76 -- Performs the division X / (Y * Z), storing the quotient in Q and
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77 -- the remainder in R. Constraint_Error is raised if Y or Z is zero,
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78 -- or if the quotient does not fit in 64-bits. Round indicates if the
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79 -- result should be rounded. If Round is False, then Q, R are the normal
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80 -- quotient and remainder from a truncating division. If Round is True,
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81 -- then Q is the rounded quotient. The remainder R is not affected by the
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82 -- setting of the Round flag.
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83
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84 end System.Arith_64;
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